VegeWorx Plant Index - Letter H
- Ha'a - Antidesma Platyphyllum H. Mann
- Ha'a - Antidesma Platyphyllum H. Mann var. platyphyllum
- Ha'i Wale - Cyrtandra Menziesii Hook. & Arn.
- Habenaria Albida (L.) R. Br var. straminea (Fernald) Morris & Eames
- Habenaria Behringiana (Rydb.) Ames
- Habenaria Bicolor (Raf.) Beckner
- Habenaria Blephariglottis (Willd.) Hook.
- Habenaria Blephariglottis (Willd.) Hook. var. conspicua (Nash) Ames
- Habenaria Blephariglottis (Willd.) Hook. var. integrilabia Correll
- Habenaria Bracteata (Muhl. ex Willd.) R. Br.
- Habenaria Chorisiana Cham.
- Habenaria Ciliaris (L.) R. Br.
- Habenaria Clavellata (Michx.) Spreng.
- Habenaria Clavellata (Michx.) Spreng. var. ophioglossoides Fernald
- Habenaria Clavellata (Michx.) Spreng. var. wrightii Olive
- Habenaria Conopsea (L.) Benth.
- Habenaria Correlliana Cronquist
- Habenaria Correllii Cronquist, orth. var.
- Habenaria Cristata (Michx.) R. Br.
- Habenaria Dilatata (Pursh) Hook.
- Habenaria Dilatata (Pursh) Hook. var. albiflora (Cham.) Correll
- Habenaria Dilatata (Pursh) Hook. var. leucostachys (Lindl.) Ames
- Habenaria Dilatata (Pursh) Hook. var. media (Rydb.) Hultén
- Habenaria Dussii Cogn.
- Habenaria Elegans (Lindl.) Bol.
- Habenaria Elegans (Lindl.) Bol. var. maritima (Greene) Ames
- Habenaria Fimbriata (Aiton) R. Br.
- Habenaria Fissa (Muhl. ex Willd.) R. Br. ex Spreng.
- Habenaria Fissa (Muhl. ex Willd.) R. Br., nom. inval.
- Habenaria Flava (L.) R. Br.
- Habenaria Flava (L.) R. Br. var. herbiola (R. Br.) Ames & Correll
- Habenaria Flava (L.) R. Br. var. virescens sensu Fernald, non Orchis virescens M
- Habenaria Floribunda Lindl. [excluded]
- Habenaria Grandiflora (Bigelow) Torr.
- Habenaria Greenei Jeps.
- Habenaria Habenaria (L.) Small, nom. inval.
- Habenaria Holochila Hillebr.
- Habenaria Hookeri Torr. ex A. Gray
- Habenaria Hookeri Torr. ex A. Gray var. abbreviata Fernald
- Habenaria Huronensis (Nutt.) Spreng.
- Habenaria Hyperborea (L.) R. Br. var. huronensis (Nutt.) Farw.
- Habenaria Hyperborea (L.) R. Br. var. viridiflora (Cham.) S.L. Welsh
- Habenaria Hyperborea auct. non (L.) R. Br.
- Habenaria Integra (Nutt.) Spreng.
- Habenaria Lacera (Michx.) R. Br.
- Habenaria Lacera (Michx.) R. Br. var. terrae-novae Fernald
- Habenaria Leucophaea (Nutt.) A. Gray
- Habenaria Leucophaea (Nutt.) A. Gray var. praeclara (Sheviak & Bowles) Cronquist
- Habenaria Leucostachys (Lindl.) S. Watson
- Habenaria Limosa (Lindl.) Hemsl.
- Habenaria Macrophylla Goldie
- Habenaria Maritima Greene
- Habenaria Media (Rydb.) Niles
- Habenaria Michaelii Greene
- Habenaria Nivea (Nutt.) Spreng.
- Habenaria Obtusata (Banks ex Pursh) Richardson
- Habenaria Obtusata (Banks ex Pursh) Richardson var. collectanea Fernald
- Habenaria Orbiculata (Pursh) Torr.
- Habenaria Orbiculata (Pursh) Torr. var. lehorsii Fernald
- Habenaria Orbiculata (Pursh) Torr. var. macrophylla (Goldie) B. Boivin
- Habenaria Orbiculata (Pursh) Torr. var. menziesii (Lindl.) Fernald
- Habenaria Palawensis Tuyama
- Habenaria Peramoena A. Gray
- Habenaria Psycodes (L.) Spreng.
- Habenaria Psycodes (L.) Spreng. var. grandiflora (Bigelow) A. Gray
- Habenaria Quinqueseta (Michx.) Eaton var. macroceratitis (Willd.) Luer
- Habenaria Saccata Greene
- Habenaria Scutellata (Nutt.) F. Morris
- Habenaria Sparsiflora S. Watson
- Habenaria Sparsiflora S. Watson var. brevifolia (Greene) Correll
- Habenaria Sparsiflora S. Watson var. laxiflora (Rydb.) Correll
- Habenaria Straminea Fernald
- Habenaria Stricta (Lindl.) Rydb.
- Habenaria Strictissima Rchb. f. var. odontopetala (Rchb. f.) L.O. Williams
- Habenaria Unalascensis (Spreng.) S. Watson
- Habenaria Unalascensis (Spreng.) S. Watson ssp. elata (Jeps.) Calder
- Habenaria Unalascensis (Spreng.) S. Watson var. elata (Jeps.) Correll
- Habenaria Unalascensis (Spreng.) S. Watson var. maritima (Greene) Correll
- Habenaria Viridis (L.) R. Br.
- Habenaria Viridis (L.) R. Br. var. bracteata (Muhl. ex Willd.) Rchb. ex A. Gray
- Habenaria Viridis (L.) R. Br. var. interjecta Fernald
- Habenaria Zothecina Higgins & S.L. Welsh
- Habenaria ×andrewsii M. White
- Habenaria ×canbyi Ames
- Habenaria ×chapmanii (Small) Ames
- Habenella Odontopetala (Rchb. f.) Small
- Habilla - Rhynchosia Reticulata (Sw.) DC.
- Habranthus Texanus Herb. ex Steud.
- Habrodon Leucotrichus (Mitt.) Perss.
- Hachuela - Pelexia Adnata (Sw.) Spreng.
- Hachuela - Pelexia Poit. ex Lindl.
- Hackberry Beardtongue - Penstemon Subulatus M.E. Jones
- Hackberry - Celtis L.
- Hackelia Americana (A. Gray) Fernald
- Hackelia Arida (Piper) I.M. Johnst.
- Hackelia Deflexa (Wahlenb.) Opiz ssp. americana (A. Gray) Á. Löve & D. Löve
- Hackelia Diffusa (Lehm.) I.M. Johnst. var. caerulescens (Rydb.) I.M. Johnst.
- Hackelia Grisea (Wooton & Standl.) I.M. Johnst.
- Hackelia Jessicae (McGregor) Brand
- Hackelia Leptophylla (Rydb.) I.M. Johnst.
- Hackelia Longituba I.M. Johnst.
- Hackelia Patens (Nutt.) I.M. Johnst. var. semiglabra Cronquist
- Hackelia Saxatilis (Piper) Brand
- Hacksaw Fern - Doodia R. Br.
- Haemanthus Katherinae Baker
- Haemanthus Multiflorus Martyn
- Haematomma Accolens (Stirt.) Hillm.
- Haematomma Americanum Kalb & Staiger
- Haematomma Californicum Sigal & D. Toren
- Haematomma Cismonicum Beltr.
- Haematomma Elatinum (Ach.) A. Massal.
- Haematomma Fenzlianum A. Massal.
- Haematomma Flexuosum Hillm.
- Haematomma Lapponicum Rasanen
- Haematomma Ochrophaeum (Tuck.) A. Massal.
- Haematomma Pacificum Hasse
- Haematomma Persoonii (Fée) A. Massal.
- Haematomma Porphyrium (Pers.) Zopf
- Haematomma Puniceum auct.
- Haematomma Pustulatum Brodo & W.L. Culb.
- Haematomma Rappii Zahlbr.
- Haematomma Rufidulum (Fée) A. Massal.
- Haematomma Subpuniceum (Fée) de Lesd.
- Haematomma Ventosum (L.) A. Massal.
- Haematoxylum - Haematoxylum L.
- Haemocharis Portoricensis Krug & Urb.
- Haenianthus - Haenianthus Griseb.
- Haenianthus Obovatus Krug & Urb.
- Haenke's Rush - Juncus Haenkei E. Mey.
- Hafellia Bahiana (Malme) Sheard
- Hafellia Bahiana (Malme) Sheard var. pleiotropa (Malme) Sheard
- Hafellia Callispora (C. Knight) H. Mayrh. & Sheard
- Hafellia Fosteri Imshaug & Sheard
- Hafellia Kalb
- Hafellia Parastata (Nyl.) Kalb
- Hafellnera Houmeau & Roux
- Hafellnera Parasemella (Nyl.) Houmeau & Roux
- Hagen's Bryum Moss - Bryum Hagenii Limpr.
- Hagen's Distichium Moss - Distichium Hagenii Ryan ex Philib.
- Hagen's Rim Lichen - Lecanora Hagenii (Ach.) Ach.
- Haggarbush - Clerodendrum Aculeatum (L.) Schltdl.
- Haha - Cyanea Duvalliorum Lammers & H. Oppenh.
- Haha - Cyanea Magnicalyx Lammers
- Haha - Cyanea Maritae Lammers & H. Oppenh.
- Haha - Gunnera Petaloidea Gaudich.
- Haha'aiakamanu - Clermontia Fauriei Levl.
- Hahala - Cyrtandra Garnotiana Gaudich.
- Hahl's Dischidia - Dischidia Hahliana Volkens
- Haid's Amygdalaria Lichen - Amygdalaria Haidensis Brodo & Hertel
- Hair-like Sedge - Carex Capillaris L.
- Hair-like Spikerush - Eleocharis Nana Kunth
- Hairawn Muhly - Muhlenbergia Capillaris (Lam.) Trin.
- Hairgrass - Aira L.
- Hairgrass - Deschampsia Alpina (L.) Roem. & Schult.
- Hairgrass - Deschampsia P. Beauv.
- Hairgrass - Rostraria Trin.
- Hairgrass - Vahlodea Fr.
- Hairless Fleabane - Erigeron Subglaber Cronquist
- Hairless Popcornflower - Plagiobothrys Glaber (A. Gray) I.M. Johnst.
- Hairpin Banksia - Banksia Spinulosa Sm.
- Hairsedge - Bulbostylis Kunth
- Hairspine Pricklypear - Opuntia Polyacantha Haw. var. polyacantha
- Hairstalk Crepidium - Crepidium Setipes (Schltr.) Szlach.
- Hairtip Clubmoss - Lycopodium Venustulum Gaudich.
- Hairtip Clubmoss - Lycopodium Venustulum Gaudich. var. venustulum
- Hairtip Clubmoss - Lycopodium Venustulum Gaudich. var. verticale W.H. Wagner
- Hairvein Fern - Hypoderris Brownii J. Sm.
- Hairy Alumroot - Heuchera Villosa Michx.
- Hairy Alumroot - Heuchera Villosa Michx. var. villosa
- Hairy Angelica - Angelica Venenosa (Greenway) Fernald
- Hairy Arnica - Arnica Mollis Hook.
- Hairy Ayenia - Ayenia Pilosa Cristobal
- Hairy Balsamroot - Balsamorhiza Hookeri (Hook.) Nutt. var. hirsuta (Nutt.) A. Nelson
- Hairy Balsamroot - Balsamorhiza Hookeri (Hook.) Nutt. var. hispidula (Sharp) Cronquist
- Hairy Banana - Musa Velutina H. Wendl. & Drude
- Hairy Beaksedge - Rhynchospora Divaricata (Ham.) M.T. Strong
- Hairy Beardtongue - Penstemon Hirsutus (L.) Willd.
- Hairy Bedstraw - Galium Pilosum Aiton
- Hairy Bedstraw - Galium Pilosum Aiton var. pilosum
- Hairy Bedstraw - Galium Pilosum Aiton var. puncticulosum (Michx.) Torr. & A. Gray
- Hairy Beggarticks - Bidens Pilosa L.
- Hairy Bigleaf Lupine - Lupinus Prunophilus M.E. Jones
- Hairy Bird's Beak - Cordylanthus Pilosus A. Gray ssp. pilosus
- Hairy Bird's Beak - Cordylanthus Pilosus A. Gray ssp. trifidus (B.L. Rob. & Greenm.) T.I. Chuang & Heckar
- Hairy Bird's-beak - Cordylanthus Pilosus A. Gray
- Hairy Bird's-foot Trefoil - Lotus Subbiflorus Lag.
- Hairy Bittercress - Cardamine Hirsuta L.
- Hairy Blazingstar - Mentzelia Hirsutissima S. Watson
- Hairy Blueberry - Vaccinium Hirsutum Buckley
- Hairy Bluestem - Andropogon Longiberbis Hack.
- Hairy Bonnet Orchid - Pleurothallis Pubescens Lindl. ex Hook.
- Hairy Brackenfern - Pteridium Aquilinum (L.) Kuhn var. pubescens Underw.
- Hairy Braya - Braya Pilosa Hook.
- Hairy Brome - Bromus Ramosus Huds.
- Hairy Bugseed - Corispermum Villosum Rydb.
- Hairy Buttercup - Ranunculus Sardous Crantz
- Hairy Butterwort - Pinguicula Villosa L.
- Hairy Caltrop - Kallstroemia Hirsutissima Vail ex Small
- Hairy Canary-clover - Dorycnium Hirsutum (L.) Ser.
- Hairy Cat's Ear - Hypochaeris Radicata L.
- Hairy Ceanothus - Ceanothus Oliganthus Nutt.
- Hairy Chaffhead - Carphephorus Paniculatus (J.F. Gmel.) Herb.
- Hairy Checkerbloom - Sidalcea Hirsuta A. Gray ex Benth.
- Hairy Clematis - Clematis Hirsutissima Pursh
- Hairy Clematis - Clematis Hirsutissima Pursh var. hirsutissima
- Hairy Clustervine - Jacquemontia Tamnifolia (L.) Griseb.
- Hairy Corkwood - Leitneria Pilosa J.A. Schrad. & W.R. Graves
- Hairy Corkwood - Leitneria Pilosa J.A. Schrad. & W.R. Graves ssp. pilosa
- Hairy Cornsalad - Valerianella Amarella (Lindh. ex Engelm.) Krok
- Hairy Crabgrass - Digitaria Sanguinalis (L.) Scop.
- Hairy Crabweed - Fatoua Villosa (Thunb.) Nakai
- Hairy Crinklemat - Tiquilia Hispidissima (Torr. & A. Gray) A.T. Richardson
- Hairy Cup Orchid - Brachionidium Ciliolatum Garay
- Hairy Cupgrass - Eriochloa Villosa (Thunb.) Kunth
- Hairy Cyanea - Cyanea Pilosa A. Gray
- Hairy Cyanea - Cyanea Pilosa A. Gray ssp. longipedunculata (Rock) Lammers
- Hairy Cyanea - Cyanea Pilosa A. Gray ssp. pilosa
- Hairy Cyrtandra - Cyrtandra Sandwicensis (Levl.) H. St. John & Storey
- Hairy Dawnflower - Stylisma Villosa (Nash) House
- Hairy Desertsunflower - Geraea Canescens Torr. & A. Gray
- Hairy Dewflower - Drosanthemum Hispidum (L.) Schwant.
- Hairy Dozedaisy - Aphanostephus Pilosus Buckley
- Hairy Evening Primrose - Oenothera Villosa Thunb.
- Hairy Evening Primrose - Oenothera Villosa Thunb. ssp. strigosa (Rydb.) W. Dietr. & P.H. Raven
- Hairy Evening Primrose - Oenothera Villosa Thunb. ssp. villosa
- Hairy False Cloak Fern - Argyrochosma Incana (C. Presl) Windham
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. ballardii (Rydb.) Semple
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. depressa (Rydb.) Semple
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. foliosa (Nutt.) V.L. Harms
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. minor (Hook.) Semple
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. nana (A. Gray) Semple
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. pedunculata (Greene) V.L. Harms ex Semple
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. scabra (Eastw.) Semple
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. sierrablancensis Semple
- Hairy False Goldenaster - Heterotheca Villosa (Pursh) Shinners var. villosa
- Hairy False Ohelo - Wikstroemia Villosa Hillebr.
- Hairy Filmy Fern - Hymenophyllum Hirsutum (L.) Sw.
- Hairy Fimbry - Fimbristylis Puberula (Michx.) Vahl
- Hairy Fimbry - Fimbristylis Puberula (Michx.) Vahl var. interior (Britton) Kral
- Hairy Fimbry - Fimbristylis Puberula (Michx.) Vahl var. puberula
- Hairy Five Eyes - Chamaesaracha Sordida (Dunal) A. Gray
- Hairy Flatsedge - Cyperus Dentoniae G. Tucker
- Hairy Fleabane - Erigeron Pubescens Kunth
- Hairy Flickingeria - Flickingeria Comata (Blume) A.D. Hawkes
- Hairy Flowering Fern - Anemia Hirsuta (L.) Sw.
- Hairy Fogfruit - Phyla Canescens (Kunth) Greene
- Hairy Forked Nailwort - Paronychia Fastigiata (Raf.) Fernald
- Hairy Forked Nailwort - Paronychia Fastigiata (Raf.) Fernald var. fastigiata
- Hairy Forked Nailwort - Paronychia Fastigiata (Raf.) Fernald var. nuttallii (Small) Fernald
- Hairy Forked Nailwort - Paronychia Fastigiata (Raf.) Fernald var. paleacea Fernald
- Hairy Four O'clock - Mirabilis Hirsuta (Pursh) MacMill.
- Hairy Fournwort - Tetramerium Nervosum Nees
- Hairy Goldenrod - Solidago Hispida Muhl. ex Willd.
- Hairy Goldenrod - Solidago Hispida Muhl. ex Willd. var. arnoglossa Fernald
- Hairy Goldenrod - Solidago Hispida Muhl. ex Willd. var. hispida
- Hairy Goldenrod - Solidago Hispida Muhl. ex Willd. var. lanata (Hook.) Fernald
- Hairy Goldenrod - Solidago Hispida Muhl. ex Willd. var. tonsa Fernald
- Hairy Grama - Bouteloua Hirsuta Lag.
- Hairy Grama - Bouteloua Hirsuta Lag. var. hirsuta
- Hairy Greenthread - Thelesperma Pubescens Dorn
- Hairy Grey Heather - Erica Canaliculata Andrews
- Hairy Gumweed - Grindelia Hirsutula Hook. & Arn.
- Hairy Gumweed - Grindelia Hirsutula Hook. & Arn. var. davyi (Jeps.) M.A. Lane
- Hairy Gumweed - Grindelia Hirsutula Hook. & Arn. var. hirsutula
- Hairy Hawkweed - Hieracium Longipilum Torr.
- Hairy Hedgenettle - Stachys Pilosa Nutt.
- Hairy Hedgenettle - Stachys Pilosa Nutt. var. arenicola (Britton) G. Mulligan & D. Munro
- Hairy Hedgenettle - Stachys Pilosa Nutt. var. pilosa
- Hairy Honeysuckle - Lonicera Hirsuta Eaton
- Hairy Horsebrush - Tetradymia Comosa A. Gray
- Hairy Indian Mallow - Abutilon Grandifolium (Willd.) Sweet
- Hairy Indian Paintbrush - Castilleja Tenuis (A. Heller) T.I. Chuang & Heckard
- Hairy Indian Paintbrush - Castilleja Tomentosa A. Gray
- Hairy Indigo - Indigofera Hirsuta L.
- Hairy Ironwort - Sideritis Lanata L.
- Hairy Jewel Orchid - Hetaeria Oblongifolia Blume
- Hairy Johnnyberry - Miconia Lanata (DC.) Triana, nom. inq.
- Hairy Jointvetch - Aeschynomene Villosa Poir.
- Hairy Jointweed - Polygonella Ciliata Meisn.
- Hairy Joyweed - Alternanthera Flavogrisea Urb.
- Hairy Kittentails - Synthyris Pinnatifida S. Watson var. canescens (Pennell) Cronquist
- Hairy Knight's-spur - Consolida Pubescens (DC.) Soó
- Hairy Lady's Mantle - Alchemilla Monticola Opiz
- Hairy Laurel - Kalmia Hirsuta Walter
- Hairy Leafcup - Smallanthus Uvedalius (L.) Mack. ex Small
- Hairy Lespedeza - Lespedeza Hirta (L.) Hornem.
- Hairy Lespedeza - Lespedeza Hirta (L.) Hornem. ssp. hirta
- Hairy Lettuce - Lactuca Hirsuta Muhl. ex Nutt.
- Hairy Lettuce - Lactuca Hirsuta Muhl. ex Nutt. var. albiflora (Torr. & A. Gray) Shinners
- Hairy Lettuce - Lactuca Hirsuta Muhl. ex Nutt. var. hirsuta
- Hairy Lettuce - Lactuca Hirsuta Muhl. ex Nutt. var. sanguinea (Bigelow) Fernald
- Hairy Lipfern - Cheilanthes Lanosa (Michx.) D.C. Eaton
- Hairy Lousewort - Pedicularis Hirsuta L.
- Hairy Manzanita - Arctostaphylos Columbiana Piper
- Hairy Marshmallow - Althaea Hirsuta L.
- Hairy Medick - Medicago Monspeliaca (L.) Trautv.
- Hairy Melicgrass - Melica Ciliata L.
- Hairy Melicope - Melicope Puberula (H. St. John) T.G. Hartley & B.C. Stone
- Hairy Milkweed - Funastrum Hirtellum (A. Gray) Schltr.
- Hairy Mock Orange - Philadelphus Incanus Koehne
- Hairy Mountain Mahogany - Cercocarpus Montanus Raf. var. paucidentatus (S. Watson) F.L. Martin
- Hairy Muhly - Muhlenbergia Villiflora Hitchc.
- Hairy Muhly - Muhlenbergia Villiflora Hitchc. var. villosa (Swallen) C.W. Morden
- Hairy Navel Lichen - Umbilicaria Hirsuta (Sw. ex Westr.) Hoffm.
- Hairy New York Aster - Symphyotrichum Novi-belgii (L.) G.L. Nesom var. villicaule (A. Gray) J. Labrecque & L. Brou
- Hairy Nightshade - Solanum Villosum (L.) Mill.
- Hairy Nutrush - Scleria Scindens Nees ex Kunth
- Hairy Orcutt Grass - Orcuttia Pilosa Hoover
- Hairy Pagoda-plant - Blephilia Hirsuta (Pursh) Benth.
- Hairy Pagoda-plant - Blephilia Hirsuta (Pursh) Benth. var. glabrata Fernald
- Hairy Pagoda-plant - Blephilia Hirsuta (Pursh) Benth. var. hirsuta
- Hairy Panicgrass - Panicum Hirsutum Sw.
- Hairy Pepperweed - Lepidium Virginicum L. var. pubescens (Greene) Thell.
- Hairy Phlox - Phlox Amoena Sims
- Hairy Phlox - Phlox Amoena Sims ssp. amoena
- Hairy Pinweed - Lechea Mucronata Raf.
- Hairy Prairie Clover - Dalea Mollis Benth.
- Hairy Primrose-willow - Ludwigia Pilosa Walter
- Hairy Purslane - Portulaca Villosa Cham.
- Hairy Purslane Speedwell - Veronica Peregrina L. ssp. xalapensis (Kunth) Pennell
- Hairy Ragweed - Ambrosia Canescens A. Gray
- Hairy Rockcress - Arabis Hirsuta (L.) Scop.
- Hairy Rockcress - Arabis Hirsuta (L.) Scop. var. hirsuta
- Hairy Rockrose - Cistus Incanus L.
- Hairy Rockrose - Cistus Incanus L. ssp. corsicus (Loisel.) Heywood
- Hairy Rockrose - Cistus Incanus L. ssp. incanus
- Hairy Rupturewort - Herniaria Hirsuta L.
- Hairy Rupturewort - Herniaria Hirsuta L. ssp. cinerea (DC.) Coutinho
- Hairy Rupturewort - Herniaria Hirsuta L. ssp. hirsuta
- Hairy Sandmat - Chamaesyce Villifera (Scheele) Small
- Hairy Sandspurry - Spergularia Villosa (Pers.) Camb.
- Hairy Schiedea - Schiedea Pentamera W.L. Wagner & E. Harris
- Hairy Schiedea - Schiedea Pubescens Hillebr.
- Hairy Schiedea - Schiedea Pubescens Hillebr. var. pubescens
- Hairy Sedge - Carex Lacustris Willd.
- Hairy Sensitive Pea - Chamaecrista Pilosa (L.) Greene
- Hairy Shadow Witch - Ponthieva Racemosa (Walter) C. Mohr
- Hairy Signalgrass - Urochloa Villosa (Lam.) T.Q. Nguyen
- Hairy Skin Lichen - Leptogium Hirsutum Sierk
- Hairy Skullcap - Scutellaria Elliptica Muhl. ex Spreng.
- Hairy Skullcap - Scutellaria Elliptica Muhl. ex Spreng. var. elliptica
- Hairy Skullcap - Scutellaria Elliptica Muhl. ex Spreng. var. hirsuta (Short & Peter) Fernald
- Hairy Small-leaf Ticktrefoil - Desmodium Ciliare (Muhl. ex Willd.) DC.
- Hairy Small-leaf Ticktrefoil - Desmodium Ciliare (Muhl. ex Willd.) DC. var. ciliare
- Hairy Smartweed - Polygonum Hirsutum Walter
- Hairy Smotherweed - Bassia Hirsuta (L.) Asch.
- Hairy Snakefern - Microgramma Piloselloides (L.) Copeland
- Hairy Solomon's Seal - Polygonatum Pubescens (Willd.) Pursh
- Hairy Spinifex - Spinifex Hirsutus Labill.
- Hairy Spotflower - Acmella Pilosa R.K. Jansen
- Hairy St. Johnswort - Hypericum Setosum L.
- Hairy Star Of Bethlehem - Gagea Villosa (M. Bieb.) Duby
- Hairy Starviolet - Hedyotis Vestita R. Br. ex G. Don
- Hairy Starviolet - Hedyotis Vestita R. Br. ex G. Don var. lutescens (Kaneh.) Fosberg
- Hairy Suncup - Camissonia Pubens (S. Watson) P.H. Raven
- Hairy Sunflower - Helianthus Hirsutus Raf.
- Hairy Thread Lichen - Ephebe Hispidula (Ach.) Horwood
- Hairy Torchwood - Amyris Diatrypa Spreng.
- Hairy Townsend Daisy - Townsendia Strigosa Nutt.
- Hairy Umbrella-sedge - Fuirena Squarrosa Michx.
- Hairy Wallaby Grass - Rytidosperma Pilosum (R. Br.) Connor & Edgar
- Hairy Waterclover - Marsilea Vestita Hook. & Grev.
- Hairy Wedelia - Wedelia Acapulcensis Kunth var. hispida (Kunth) Strother
- Hairy White Oldfield Aster - Symphyotrichum Pilosum (Willd.) G.L. Nesom
- Hairy White Oldfield Aster - Symphyotrichum Pilosum (Willd.) G.L. Nesom var. pilosum
- Hairy Whitetop - Cardaria Pubescens (C.A. Mey.) Jarmolenko
- Hairy Wild Cabbage - Caulanthus Pilosus S. Watson
- Hairy Wild Coffee - Psychotria Pubescens Sw.
- Hairy Wildrye - Elymus Villosus Muhl. ex Willd.
- Hairy Woodland Brome - Bromus Pubescens Muhl. ex Willd.
- Hairy Woodrose - Merremia Aegyptia (L.) Urb.
- Hairy Woodrush - Luzula Acuminata Raf.
- Hairy Woodrush - Luzula Acuminata Raf. ssp. acuminata
- Hairy Woollygrass - Erioneuron Pilosum (Buckley) Nash
- Hairy Wreath Lichen - Phaeophyscia Hirsuta (Mereschk.) Essl.
- Hairy Yellow Vetch - Vicia Hybrida L.
- Hairy Yellow Vetch - Vicia Lutea L. ssp. vestita (Boiss.) Rouy
- Hairy Yerba Santa - Eriodictyon Trichocalyx A. Heller
- Hairy Yerba Santa - Eriodictyon Trichocalyx A. Heller var. lanatum (Brand) Jeps.
- Hairy Yerba Santa - Eriodictyon Trichocalyx A. Heller var. trichocalyx
- Hairy-fruit Spurge - Euphorbia Cuphosperma (Engelm.) Boiss.
- Hairy-lemma Barley - ×elyhordeum Pilosilemma (Mitchell & Hodgson) Barkworth
- Hairy-pod Milkvetch - Astragalus Concordius S.L. Welsh
- Hairy-seed Goldenrod - Solidago Villosicarpa LeBlond
- Hairy-tuft Four O'clock - Mirabilis Comata (Small) Standl.
- Hairybeast Turtleback - Psathyrotes Pilifera A. Gray
- Hairybroom - Cytisus Villosus Pourr.
- Hairyflower Alpinia - Alpinia Pubiflora (Benth.) K. Schum.
- Hairyflower Bellflower - Campanula Chamissonis Fedorov
- Hairyflower Buckwheat - Eriogonum Hirtiflorum A. Gray ex S. Watson
- Hairyflower Lovegrass - Eragrostis Trichophora Coss. & Durand
- Hairyflower Melicope - Melicope Trichantha (Lauterb.) T.G. Hartley
- Hairyflower Spiderwort - Tradescantia Hirsutiflora Bush
- Hairyflower Wild Petunia - Ruellia Ciliatiflora Hook.
- Hairyfruit Chervil - Chaerophyllum Tainturieri Hook.
- Hairyfruit Chervil - Chaerophyllum Tainturieri Hook. var. dasycarpum Hook. ex S. Watson
- Hairyfruit Chervil - Chaerophyllum Tainturieri Hook. var. tainturieri
- Hairyfruit Chewstick - Gouania Hillebrandii Oliv. ex Hillebr.
- Hairyfruit Sedge - Carex Trichocarpa Muhl. ex Willd.
- Hairyfruit Valerian - Valeriana Acutiloba Rydb. var. pubicarpa (Rydb.) Cronquist
- Hairyjoint Meadowparsnip - Thaspium Barbinode (Michx.) Nutt.
- Hairyleaf Bristlegrass - Setaria Villosissima (Scribn. & Merr.) K. Schum.
- Hairyleaf Dewberry - Rubus Plus L.H. Bailey
- Hairyleaf Nervilia - Nervilia Trichophylla Fukuy.
- Hairyleaf Rush - Juncus Supiniformis Engelm.
- Hairypink - Petrorhagia Dubia (Raf.) G. López & Romo
- Hairypod Cowpea - Vigna Luteola (Jacq.) Benth.
- Hairyseed Bahia - Bahia Absinthifolia Benth.
- Hairyseed Bahia - Bahia Absinthifolia Benth. var. absinthifolia
- Hairyseed Paspalum - Paspalum Pubiflorum Rupr. ex Fourn.
- Hairysheath Lovegrass - Eragrostis Polytricha Nees
- Hairystem Dwarf Rush - Juncus Capillaris F.J. Herm.
- Hairystem Gooseberry - Ribes Hirtellum Michx.
- Hairystem Rockcress - Arabis Sparsiflora Nutt. var. subvillosa (S. Watson) Rollins
- Hairystem Spiderwort - Tradescantia Hirsuticaulis Small
- Hairytwig Huckleberry - Gaylussacia Tomentosa (A. Gray) Pursh ex Small
- Haitian Catalpa - Catalpa Longissima (Jacq.) Dum. Cours.
- Hakone Grass - Hakonechloa Macra (Munro) Makino
- Hakone Grass - Hakonechloa Makino ex Honda
- Hala Pepe - Pleomele Salisb.
- Halberd Fern - Tectaria Cav.
- Halberd Fern - Tectaria ×amesiana A.A. Eaton (pro sp.)
- Halberd Willow - Salix Hastata L.
- Halberdleaf Orach - Atriplex Calotheca (Rafn) Fr.
- Halberdleaf Rosemallow - Hibiscus Laevis All.
- Halberdleaf Tearthumb - Polygonum Arifolium L.
- Halberdleaf Yellow Violet - Viola Hastata Michx.
- Hale's Melanelia Lichen - Melanelia Halei (Ahti) Essl.
- Hale's Pentodon - Pentodon Pentandrus (Schumach. & Thonn.) Vatke
- Hale's Phyllopsora Lichen - Phyllopsora Halei (Tuck.) Zahlbr.
- Hale's Rinodina Lichen - Rinodina Halei H. Magn.
- Hale's Rosette Lichen - Physcia Halei J.W. Thomson
- Halea Ludoviciana Torr. & A. Gray
- Halea Repanda Buckley
- Haleakala Catchfly - Silene Cryptopetala Hillebr.
- Haleakala Clermontia - Clermontia Tuberculata Forbes
- Haleakala Cyanea - Cyanea Aculeatiflora Rock
- Haleakala Lobelia - Lobelia Grayana E. Wimm.
- Haleakala Melicope - Melicope Haleakalae (B.C. Stone) T.G. Hartley & B.C. Stone
- Haleakala Sandalwood - Santalum Haleakalae Hillebr.
- Haleakala Schiedea - Schiedea Haleakalensis O. Deg. & Sherff
- Haleakala Spleenwort - Asplenium Haleakalense W.H. Wagner
- Haleakala Starviolet - Hedyotis Foliosa (Hillebr.) Fosberg
- Haleakala Stenogyne - Stenogyne Haliakalae Wawra
- Haleakala Tetramolopium - Tetramolopium Humile (A. Gray) Hillebr. ssp. haleakalae Lowrey
- Halecania Lichen - Halecania Alpivaga (Th. Fr.) M. Mayrh.
- Halecania Lichen - Halecania M. Mayrh.
- Halecania Viridescens Coppins & P. James
- Halenia Recurva (Sm.) Allen, nom. utique rej.
- Halerpestes Cymbalaria (Pursh) Greene
- Halerpestes Cymbalaria (Pursh) Greene ssp. saximontana (Fernald) Moldenke
- Halesia Carolina L. var. monticola Rehder
- Halesia Diptera Ellis var. magniflora Godfrey
- Halesia Monticola (Rehder) Sarg.
- Halesia Monticola (Rehder) Sarg. var. vestita Sarg.
- Halesia Parviflora Michx.
- Halfchaff Sedge - Lipocarpha R. Br.
- Halfmoon Milkvetch - Astragalus Allochrous A. Gray
- Halfmoon Milkvetch - Astragalus Wootonii Sheldon
- Halfnetfern - Hemidictyum Marginatum (L.) C. Presl
- Halfshrub Rockmat - Petrophytum Cinerascens (Piper) Rydb.
- Halifax Blackberry - Rubus Russeus L.H. Bailey
- Halimione Aellen
- Halimione Portulacoides (L.) Aellen [excluded]
- Halimodendron - Halimodendron Fisch. ex DC.
- Halimolobos Diffusa (A. Gray) O.E. Schulz var. jaegeri (Munz) Rollins
- Hall Crab Apple - Malus Halliana Koehne
- Hall's Archidium Moss - Archidium Hallii Austin
- Hall's Arthothelium Lichen - Arthothelium Hallii (Tuck.) Zahlbr.
- Hall's Aster - Symphyotrichum Hallii (A. Gray) G.L. Nesom
- Hall's Beardtongue - Penstemon Hallii A. Gray
- Hall's Bedstraw - Galium Hallii Munz & I.M. Johnst.
- Hall's Bentgrass - Agrostis Hallii Vasey
- Hall's Biscuitroot - Lomatium Hallii (S. Watson) J.M. Coult. & Rose
- Hall's Bruchia Moss - Bruchia Hallii Austin
- Hall's Bulrush - Schoenoplectiella Hallii (A.Gray) Lye
- Hall's Bush Lupine - Lupinus Excubitus M.E. Jones var. hallii (Abrams) C.P. Sm.
- Hall's California Tea - Rupertia Hallii (Rydb.) J. Grimes
- Hall's Columbiadoria - Columbiadoria Hallii (A. Gray) G.L. Nesom
- Hall's Fissidens Moss - Fissidens Hallii Austin
- Hall's Fleabane - Erigeron Aequifolius H.M. Hall
- Hall's Gumweed - Grindelia Hirsutula Hook. & Arn. var. hallii (Steyerm. ex Rothr.) M.A. Lane
- Hall's Hawksbeard - Crepis Runcinata (James) Torr. & A. Gray ssp. hallii Babc. & Stebbins
- Hall's Lung Lichen - Lobaria Hallii (Tuck.) Zahlbr.
- Hall's Madia - Harmonia Hallii (D.D. Keck) B.G. Baldw.
- Hall's Milkvetch - Astragalus Hallii A. Gray
- Hall's Milkvetch - Astragalus Hallii A. Gray var. fallax (M.E. Jones) Barneby
- Hall's Milkvetch - Astragalus Hallii A. Gray var. hallii
- Hall's Milkweed - Asclepias Hallii A. Gray
- Hall's Monardella - Monardella Macrantha A. Gray ssp. hallii (Abrams) Abrams
- Hall's Mule-ears - Agnorhiza Elata (H.M. Hall) W.A. Weber
- Hall's Orthotrichum Moss - Orthotrichum Hallii Sull. & Lesq.
- Hall's Panicgrass - Panicum Hallii Vasey
- Hall's Panicgrass - Panicum Hallii Vasey var. filipes (Scribn.) Waller
- Hall's Panicgrass - Panicum Hallii Vasey var. hallii
- Hall's Phaeoceros - Phaeoceros Hallii (Austin) Prosk.
- Hall's Prairie Clover - Dalea Hallii A. Gray
- Hall's Ragwort - Senecio Bigelovii A. Gray var. hallii A. Gray
- Hall's Rinodina Lichen - Rinodina Hallii Tuck.
- Hall's Rush - Juncus Hallii Engelm.
- Hall's Sedge - Carex Halliana L.H. Bailey
- Hall's Shrubby-spurge - Tetracoccus Hallii Brandegee
- Hall's Suncup - Camissonia Pallida (Abrams) P.H. Raven ssp. hallii (Davidson) P.H. Raven
- Hall's Tarweed - Deinandra Halliana (D.D. Keck) B.G. Baldw.
- Hall's Wild Cabbage - Caulanthus Hallii Payson
- Hall's Woolly Sunflower - Eriophyllum Lanatum (Pursh) Forbes var. hallii Constance
- Haller's Bartramia Moss - Bartramia Halleriana Hedw.
- Haller's Campylium Moss - Campylium Halleri (Hedw.) Lindb.
- Halliophytum Fasciculatum (S. Watson) I.M. Johnst. var. hallii (Brandegee) McMinn
- Halliophytum Fasciculatum auct. non (S. Watson) I.M. Johnst.
- Halliophytum Hallii (Brandegee) I.M. Johnst.
- Halmia Tomentosa M. Roem. var. pyrifolia (Lam.) M. Roem.
- Halocnemum M. Bieb.
- Halocnemum Strobilaceum (Pall.) M. Bieb.
- Halodule Beaudettei (Hartog) Hartog
- Halodule - Halodule Endl.
- Halodule - Halodule Uninervis Boiss.
- Halophila Aschersonii Ostenf.
- Halophila Ovalis (R. Br.) Hook. f. ssp. hawaiiana (Doty & B.C. Stone) Hartog
- Haloragis Acanthocarpa Brongn.
- Haloragis Chinensis (Lour.) Merrill
- Haloscias Hultenii (Fernald) Holub
- Halostachys Occidentalis S. Watson
- Hamakua Clermontia - Clermontia Pyrularia Hillebr.
- Hamamelis Macrophylla Pursh
- Hamamelis Vernalis Sarg. var. tomentella (Rehder) Palmer
- Hamamelis Virginiana L. var. henryae Jenne ex C. Lane
- Hamamelis Virginiana L. var. macrophylla (Pursh) Nutt.
- Hamamelis Virginiana L. var. parvifolia Nutt.
- Hamatocactus - Hamatocactus Britton & Rose
- Hamatocactus Hamatocanthus (Muhlph.) F.M. Kunth
- Hamatocaulis Moss - Hamatocaulis Hedenäs
- Hamatocaulis Moss - Hamatocaulis Vernicosus (Mitt.) Hedenäs
- Hamblen's Biscuitroot - Lomatium Farinosum (Hook.) J.M. Coult. & Rose var. hambleniae (Mathias & Constance)
- Hame - Antidesma Pulvinatum Hillebr.
- Hamelia Erecta Jacq.
- Hamelia - Hamelia Jacq.
- Hamilton's Milkvetch - Astragalus Hamiltonii Ced. Porter
- Hamilton's Spindletree - Euonymus Hamiltonianus Wall.
- Hamilton's Spindletree - Euonymus Hamiltonianus Wall. ssp. maackii (Rupr.) Kom.
- Hamilton's Spindletree - Euonymus Hamiltonianus Wall. ssp. sieboldianus (Blume) H. Hara
- Hammarbya Paludosa (L.) Kuntze
- Hammer Sedge - Carex Hirta L.
- Hammitt's Claycress - Sibaropsis Hammittii S. Boyd & T.S. Ross
- Hammock Bog Orchid - Habenaria Distans Griseb.
- Hammock Fern - Blechnum Occidentale L.
- Hammock Sedge - Carex Fissa Mack.
- Hammock Sedge - Carex Fissa Mack. var. aristata F.J. Herm.
- Hammock Sedge - Carex Fissa Mack. var. fissa
- Hammock Shrubverbena - Lantana Canescens Kunth
- Hammock Snakeroot - Ageratina Jucunda (Greene) Clewell & Wooten
- Hammock Velvetseed - Guettarda Elliptica Sw.
- Hammock Viper's-tail - Pentalinon Luteum (L.) B.F. Hansen & Wunderlin
- Hammockherb - Hasteola Robertiorum L.C. Anderson
- Hammond's Claytonia - Claytonia Virginica L. var. hammondiae (Kalmbacher) Doyle, W.H. Lewis & Snyder
- Hamosa Leptocarpa (Torr. & A. Gray) Rydb.
- Hampe's Entodon Moss - Entodon Hampeanus Müll. Hal.
- Hampton False Foxglove - Agalinis Flexicaulis Hays
- Hamulium Alatum (L.) Cass.
- Hana Clermontia - Clermontia Samuelii Forbes
- Hana Clermontia - Clermontia Samuelii Forbes ssp. hanaensis (H. St. John) Lammers
- Hana Clermontia - Clermontia Samuelii Forbes ssp. samuelii
- Hana Forest Silversword - Argyroxiphium Grayanum (Hillebr.) O. Deg.
- Hana Melicope - Melicope Ovalis (H. St. John) T.G. Hartley & B.C. Stone
- Hanapepe River Colicwood - Myrsine Mezii Hosaka
- Hanaupah Rockdaisy - Perityle Villosa (S.F. Blake) Shinners
- Hanbury's Garcinia - Garcinia Hanburyi Hook. f.
- Hancornia - Hancornia B.a. Gomes
- Hand Bonnet Orchid - Pleurothallis Appendiculata Cogn.
- Hand Fern - Cheiroglossa Palmata (L.) C. Presl
- Handsome Beardtongue - Penstemon Lentus Pennell
- Handsome Beardtongue - Penstemon Lentus Pennell var. albiflorus (D.D. Keck) Reveal
- Handsome Beardtongue - Penstemon Lentus Pennell var. lentus
- Handsome Cryptantha - Cryptantha Paradoxa (A. Nelson) Payson
- Handsome Harry - Rhexia Virginica L.
- Handsome Phacelia - Phacelia Peirsoniana J.T. Howell
- Handsome Pussy-toes - Antennaria Pulcherrima (Hook.) Greene ssp. pulcherrima
- Handsome Sedge - Carex Formosa Dewey
- Handsome Spikemoss - Selaginella Subcaulescens Baker
- Hanes' Blackberry - Rubus Hanesii L.H. Bailey
- Hanging Clubmoss - Huperzia Dichotoma (Jacq.) Trevis.
- Hanging Sedge - Carex Pendula Huds.
- Hangingpod Milkvetch - Astragalus Atropubescens J.M. Coult. & Fisher
- Hanguana Blume
- Hanguana Malayana Merrill
- Hansen's Bird's Beak - Cordylanthus Pilosus A. Gray ssp. hansenii (Ferris) T.I. Chuang & Heckard
- Hansen's Cinquefoil - Potentilla Glandulosa Lindl. ssp. hansenii (Greene) D.D. Keck
- Hansen's Clover - Trifolium Longipes Nutt. ssp. hansenii (Greene) J.M. Gillett
- Hansen's Spikemoss - Selaginella Hansenii Hieron.
- Hapalanthus Repens Jacq.
- Hapalorchis - Hapalorchis Schltr.
- Hapalorchis Tenuis (Lindl.) Schltr.
- Hapeman's Coolwort - Sullivantia Hapemanii (J.M. Coult. & Fisher) J.M. Coult.
- Hapeman's Coolwort - Sullivantia Hapemanii (J.M. Coult. & Fisher) J.M. Coult. var. hapemanii
- Haplocladium Angustifolium (Hampe & Müll. Hal.) Broth.
- Haplocladium Microphyllum (Hedw.) Broth.
- Haplocladium Microphyllum (Hedw.) Broth. var. lignicola (Kindb.) Reim.
- Haplocladium Microphyllum (Hedw.) Broth. var. obtusum (Grout) H.A. Crum
- Haplocladium Praelongum (Schimp. ex Besch.) H.A. Crum
- Haplocladium Virginianum (Brid.) Broth.
- Haplohymenium Moss - Haplohymenium Dozy & Molk.
- Haplohymenium Moss - Haplohymenium Triste (Ces.) Kindb.
- Haplomitrium Hookeri (Sm.) Nees
- Haplomitrium Hookeri (Sm.) Nees var. hookeri
- Haplomitrium Nees, nom. cons.
- Haplopappus Aberrans (A. Nelson) H.M. Hall
- Haplopappus Acaulis (Nutt.) A. Gray
- Haplopappus Acaulis (Nutt.) A. Gray ssp. typicus H.M. Hall
- Haplopappus Acaulis (Nutt.) A. Gray var. glabratus D.C. Eaton
- Haplopappus Acradenius (Greene) S.F. Blake
- Haplopappus Acradenius (Greene) S.F. Blake ssp. bracteosus (Greene) H.M. Hall
- Haplopappus Acradenius (Greene) S.F. Blake ssp. eremophilus (Greene) H.M. Hall
- Haplopappus Alpigenus Torr. & A. Gray
- Haplopappus Alpinus L.C. Anderson & Goodrich
- Haplopappus Annuus (Rydb.) Cory
- Haplopappus Apargioides A. Gray
- Haplopappus Arborescens (A. Gray) H.M. Hall
- Haplopappus Armerioides (Nutt.) A. Gray
- Haplopappus Armerioides (Nutt.) A. Gray var. gramineus S.L. Welsh & F.J. Sm.
- Haplopappus Aureus A. Gray
- Haplopappus Blephariphyllus A. Gray
- Haplopappus Bloomeri A. Gray
- Haplopappus Bloomeri A. Gray ssp. compactus H.M. Hall
- Haplopappus Bloomeri A. Gray ssp. sonnei (A. Gray) H.M. Hall
- Haplopappus Bloomeri A. Gray var. angustatus A. Gray
- Haplopappus Bloomeri A. Gray var. greenei (A. Gray) Cronquist
- Haplopappus Bloomeri A. Gray var. ophitidis J.T. Howell
- Haplopappus Bloomeri A. Gray var. sonnei (A. Gray) Greene
- Haplopappus Brandegeei A. Gray
- Haplopappus Brickellioides S.F. Blake
- Haplopappus Canus (A. Gray) S.F. Blake
- Haplopappus Carthamoides (Hook.) A. Gray
- Haplopappus Carthamoides (Hook.) A. Gray ssp. cusickii (A. Gray) H.M. Hall
- Haplopappus Carthamoides (Hook.) A. Gray ssp. rigidus (Rydb.) H.M. Hall
- Haplopappus Carthamoides (Hook.) A. Gray var. cusickii A. Gray
- Haplopappus Carthamoides (Hook.) A. Gray var. erythropappus (Rydb.) H. St. John
- Haplopappus Carthamoides (Hook.) A. Gray var. maximus A. Gray
- Haplopappus Carthamoides (Hook.) A. Gray var. rigidus (Rydb.) M. Peck
- Haplopappus Carthamoides (Hook.) A. Gray var. subsquarrosus (Greene) Dorn
- Haplopappus Carthamoides (Hook.) A. Gray var. typicus (H.M. Hall) Cronquist
- Haplopappus Cervinus S. Watson
- Haplopappus Ciliatus (Nutt.) DC.
- Haplopappus Clementis (Rydb.) S.F. Blake
- Haplopappus Coloradoensis (A. Gray) R.L. Hartm. ex Dorn
- Haplopappus Compactus (H.M. Hall) L.C. Anderson
- Haplopappus Contractus H.M. Hall
- Haplopappus Cooperi (A. Gray) H.M. Hall
- Haplopappus Coulteri Harv. & A. Gray ex A. Gray
- Haplopappus Crispus L.C. Anderson
- Haplopappus Croceus A. Gray
- Haplopappus Croceus A. Gray ssp. typicus H.M. Hall
- Haplopappus Croceus A. Gray var. genuflexus (Greene) S.F. Blake
- Haplopappus Cuneatus A. Gray
- Haplopappus Cuneatus A. Gray var. spathulatus (A. Gray) S.F. Blake ex Munz
- Haplopappus Detonsus (Greene) P.H. Raven
- Haplopappus Divaricatus (Nutt.) A. Gray
- Haplopappus Divaricatus (Nutt.) A. Gray var. hookerianus (Torr. & A. Gray) Waterf.
- Haplopappus Drummondii (Torr. & A. Gray) S.F. Blake
- Haplopappus Eastwoodiae H.M. Hall
- Haplopappus Engelmannii (A. Gray) H.M. Hall
- Haplopappus Ericoides (Less.) Hook. & Arn.
- Haplopappus Ericoides (Less.) Hook. & Arn. ssp. blakei C.B. Wolf
- Haplopappus Eximius H.M. Hall
- Haplopappus Eximius H.M. Hall ssp. peirsonii D.D. Keck
- Haplopappus Fremontii (A. Gray) Greene
- Haplopappus Fremontii (A. Gray) Greene ssp. monocephalus (A. Nelson) H.M. Hall
- Haplopappus Fremontii (A. Gray) Greene ssp. typicus H.M. Hall
- Haplopappus Fremontii (A. Gray) Greene ssp. wardii (A. Gray) H.M. Hall
- Haplopappus Gilmanii S.F. Blake
- Haplopappus Gooddingii (A. Nelson) Munz & I.M. Johnst.
- Haplopappus Gracilis (Nutt.) A. Gray
- Haplopappus Graniticus Tiehm & L.M. Shultz
- Haplopappus Greenei A. Gray
- Haplopappus Greenei A. Gray var. mollis A. Gray
- Haplopappus Gymnocephalus DC.
- Haplopappus Hallii A. Gray
- Haplopappus - Haplopappus Cass.
- Haplopappus Havardii Waterf.
- Haplopappus Heterophyllus (A. Gray) S.F. Blake
- Haplopappus Hirtus A. Gray
- Haplopappus Hirtus A. Gray ssp. lanulosus (Greene) H.M. Hall
- Haplopappus Hirtus A. Gray ssp. sonchifolius (Greene) H.M. Hall
- Haplopappus Hirtus A. Gray ssp. typicus H.M. Hall
- Haplopappus Hirtus A. Gray var. lanulosus (Greene) M. Peck
- Haplopappus Hirtus A. Gray var. sonchifolius (Greene) M. Peck
- Haplopappus Insecticruris (L.F. Hend.) A. Heller
- Haplopappus Integrifolius Porter ex A. Gray
- Haplopappus Integrifolius Porter ex A. Gray ssp. insecticruris (L.F. Hend.) H.M. Hall
- Haplopappus Integrifolius Porter ex A. Gray ssp. liatriformis (Greene) H.M. Hall
- Haplopappus Integrifolius Porter ex A. Gray ssp. scaberulus (Greene) H.M. Hall
- Haplopappus Integrifolius Porter ex A. Gray ssp. typicus H.M. Hall
- Haplopappus Junceus Greene
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray ssp. solidagineus (Greene) H.M. Hall
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray ssp. tenuicaulis (D.C. Eaton) H.M. Hall
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray ssp. vaseyi (Parry ex D.C. Eaton) H.M. H
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray var. sublanatus Cody
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray var. tenuicaulis (D.C. Eaton) A. Gray
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray var. typicus (H.M. Hall) Cronquist
- Haplopappus Lanceolatus (Hook.) Torr. & A. Gray var. vaseyi Parry ex D.C. Eaton
- Haplopappus Lanuginosus A. Gray
- Haplopappus Lanuginosus A. Gray ssp. andersonii (Rydb.) H.M. Hall
- Haplopappus Lanuginosus A. Gray ssp. typicus H.M. Hall
- Haplopappus Lanuginosus A. Gray var. andersonii (Rydb.) Cronquist
- Haplopappus Laricifolius A. Gray
- Haplopappus Leverichii Cronquist
- Haplopappus Liatriformis (Greene) H. St. John
- Haplopappus Lignumviridis S.L. Welsh
- Haplopappus Linearifolius DC.
- Haplopappus Linearifolius DC. ssp. interior (Coville) H.M. Hall
- Haplopappus Linearifolius DC. var. interior (Coville) M.E. Jones
- Haplopappus Lucidus (D.D. Keck) D.D. Keck
- Haplopappus Lyallii A. Gray
- Haplopappus Macronema (Nutt.) A. Gray
- Haplopappus Macronema (Nutt.) A. Gray var. canescens (A. Nelson) Cronquist
- Haplopappus Macronema (Nutt.) A. Gray var. linearis (Rydb.) Dorn
- Haplopappus Macronema (Nutt.) A. Gray var. typicus H.M. Hall
- Haplopappus Microcephalus Cronquist
- Haplopappus Multicaulis (Nutt.) A. Gray
- Haplopappus Nanus (Nutt.) D.C. Eaton
- Haplopappus Nuttallii Torr. & A. Gray
- Haplopappus Nuttallii Torr. & A. Gray var. depressus Maguire
- Haplopappus Ophitidis (J.T. Howell) D.D. Keck
- Haplopappus Palmeri A. Gray
- Haplopappus Palmeri A. Gray ssp. pachylepis H.M. Hall
- Haplopappus Paniculatus (Nutt.) A. Gray var. virgatus A. Gray
- Haplopappus Parishii (Greene) S.F. Blake
- Haplopappus Parryi A. Gray
- Haplopappus Peirsonii (D.D. Keck) J.T. Howell
- Haplopappus Phyllocephalus DC.
- Haplopappus Phyllocephalus DC. ssp. annuus (Rydb.) H.M. Hall
- Haplopappus Phyllocephalus DC. var. annuus (Rydb.) Waterf.
- Haplopappus Phyllocephalus DC. var. megacephalus (Nash) Waterf.
- Haplopappus Pinifolius A. Gray
- Haplopappus Pluriflorus (Torr. & A. Gray) H.M. Hall
- Haplopappus Propinquus S.F. Blake
- Haplopappus Pygmaeus (Torr. & A. Gray) A. Gray
- Haplopappus Racemosus (Nutt.) Torr.
- Haplopappus Racemosus (Nutt.) Torr. ssp. brachycephalus (A. Nelson) H.M. Hall
- Haplopappus Racemosus (Nutt.) Torr. ssp. congestus (Greene) H.M. Hall
- Haplopappus Racemosus (Nutt.) Torr. ssp. duriuscula (Greene) H.M. Hall
- Haplopappus Racemosus (Nutt.) Torr. ssp. glomeratus (Nutt.) H.M. Hall
- Haplopappus Racemosus (Nutt.) Torr. ssp. halophilus (Greene) H.M. Hall
- Haplopappus Racemosus (Nutt.) Torr. ssp. liatriformis (Greene) D.D. Keck
- Haplopappus Racemosus (Nutt.) Torr. ssp. lucidus D.D. Keck
- Haplopappus Racemosus (Nutt.) Torr. ssp. pinetorum D.D. Keck
- Haplopappus Racemosus (Nutt.) Torr. ssp. prionophyllus (Greene) H.M. Hall
- Haplopappus Racemosus (Nutt.) Torr. ssp. sessiliflorus (Greene) H.M. Hall
- Haplopappus Racemosus (Nutt.) Torr. var. glomerellus (Nutt.) A. Gray
- Haplopappus Racemosus (Nutt.) Torr. var. paniculatus (Nutt.) Cronquist
- Haplopappus Racemosus (Nutt.) Torr. var. prionophyllus (Greene) S.L. Welsh
- Haplopappus Racemosus (Nutt.) Torr. var. sessiliflorus (Greene) S.L. Welsh
- Haplopappus Radiatus (Nutt.) Cronquist
- Haplopappus Ravenii R.C. Jacks.
- Haplopappus Resinosus (Nutt.) A. Gray
- Haplopappus Rigidifolius E.B. Sm.
- Haplopappus Rusbyi (Greene) Cronquist
- Haplopappus Rydbergii S.F. Blake
- Haplopappus Salicinus S.F. Blake
- Haplopappus Scopulorum (M.E. Jones) S.F. Blake
- Haplopappus Scopulorum (M.E. Jones) S.F. Blake var. hirtellus S.F. Blake
- Haplopappus Spinulosus (Pursh) DC.
- Haplopappus Spinulosus (Pursh) DC. ssp. australis (Greene) H.M. Hall
- Haplopappus Spinulosus (Pursh) DC. ssp. cotulus (Small) H.M. Hall
- Haplopappus Spinulosus (Pursh) DC. ssp. glaberrimus (Rydb.) H.M. Hall
- Haplopappus Spinulosus (Pursh) DC. ssp. laevis (Wooton & Standl.) H.M. Hall
- Haplopappus Spinulosus (Pursh) DC. ssp. scabrellus (Greene) H.M. Hall
- Haplopappus Spinulosus (Pursh) DC. var. canescens A. Gray
- Haplopappus Spinulosus (Pursh) DC. var. chihuahuanus (B.L. Turner & R.L. Hartm.) Gandhi
- Haplopappus Spinulosus (Pursh) DC. var. glaber A. Gray
- Haplopappus Spinulosus (Pursh) DC. var. glaberrimus (Rydb.) S.F. Blake
- Haplopappus Spinulosus (Pursh) DC. var. gooddingii (A. Nelson) S.F. Blake
- Haplopappus Spinulosus (Pursh) DC. var. paradoxa (B.L. Turner & R.L. Hartm.) Cronquist
- Haplopappus Spinulosus (Pursh) DC. var. scabrellus (Greene) S.F. Blake
- Haplopappus Spinulosus (Pursh) DC. var. turbinellus (Rydb.) S.F. Blake
- Haplopappus Squarrosus Hook. & Arn.
- Haplopappus Squarrosus Hook. & Arn. ssp. grindelioides (DC.) D.D. Keck
- Haplopappus Squarrosus Hook. & Arn. ssp. obtusus (Greene) H.M. Hall
- Haplopappus Squarrosus Hook. & Arn. ssp. stenolepis H.M. Hall
- Haplopappus Stenophyllus A. Gray
- Haplopappus Subviscosus (Greene) S.F. Blake
- Haplopappus Suffruticosus (Nutt.) A. Gray
- Haplopappus Tenuisectus (Greene) S.F. Blake
- Haplopappus Texensis R.C. Jacks.
- Haplopappus Trianthus S.F. Blake
- Haplopappus Uniflorus (Hook.) Torr. & A. Gray
- Haplopappus Uniflorus (Hook.) Torr. & A. Gray ssp. gossypinus (Greene) H.M. Hall
- Haplopappus Uniflorus (Hook.) Torr. & A. Gray ssp. howellii (A. Gray) H.M. Hall
- Haplopappus Uniflorus (Hook.) Torr. & A. Gray ssp. linearis D.D. Keck
- Haplopappus Uniflorus (Hook.) Torr. & A. Gray ssp. typicus H.M. Hall
- Haplopappus Uniflorus (Hook.) Torr. & A. Gray var. howellii (A. Gray) M. Peck
- Haplopappus Validus (Rydb.) Cory
- Haplopappus Validus (Rydb.) Cory ssp. graniticus E.B. Sm.
- Haplopappus Validus (Rydb.) Cory ssp. torreyi E.B. Sm.
- Haplopappus Venetus (Kunth) S.F. Blake
- Haplopappus Venetus (Kunth) S.F. Blake ssp. furfuraceus (Greene) H.M. Hall
- Haplopappus Venetus (Kunth) S.F. Blake ssp. oxyphyllus (Greene) H.M. Hall
- Haplopappus Venetus (Kunth) S.F. Blake ssp. vernonioides (Nutt.) H.M. Hall
- Haplopappus Venetus (Kunth) S.F. Blake var. argutus (Greene) D.D. Keck
- Haplopappus Venetus (Kunth) S.F. Blake var. sedoides (Greene) Munz
- Haplopappus Wardii (A. Gray) Dorn
- Haplopappus Watsonii A. Gray
- Haplopappus Watsonii A. Gray var. rydbergii (S.F. Blake) S.L. Welsh
- Haplopappus Whitneyi A. Gray
- Haplopappus Whitneyi A. Gray ssp. discoideus (J.T. Howell) D.D. Keck
- Haplopappus Zionis L.C. Anderson
- Haplophyton Cimicidum A. DC. var. crooksii L.D. Benson
- Haplophyton Cimicidum auct. non A. DC.
- Haplophyton - Haplophyton A. DC.
- Haplopteris Elongata (Sw.) E.H. Crane
- Haplostachys Bryanii Sherff var. microdonta Sherff
- Haplostachys Bryanii Sherff var. robusta Sherff
- Haplostachys Haplostachya (A. Gray) H. St. John var. angustifolia (Sherff) H. St. John
- Haplostachys Haplostachya (A. Gray) H. St. John var. leptostachya (Hillebr.) H. St. John
- Haplostachys - Haplostachys (a. Gray) Hillebr.
- Haplostachys Linearifolia (Drake) Sherff var. rosmarinifolia (Hillebr.) Sherff
- Hapu'u - Cibotium Glaucum (Sm.) Hook. & Arn.
- Hapu'u Li - Cibotium Menziesii Hook.
- Harbinger Of Spring - Erigenia Bulbosa (Michx.) Nutt.
- Harbison Oak - Quercus ×harbisonii Sarg.
- Harbison's Hawthorn - Crataegus Harbisonii Beadle
- Harbour's Beardtongue - Penstemon Harbourii A. Gray
- Harbouria - Harbouria J.m. Coult. & Rose
- Hard Alumroot - Heuchera Duranii Bacig.
- Hard Fescue - Festuca Brevipila Tracey
- Hard Spinifex - Triodia Basedowii E. Pritz.
- Hard Treefern - Dicksonia Squarrosa (G. Forst.) Sw.
- Hard Wallflower - Erysimum Marschallianum Andrz. ex M. Bieb.
- Hardee Peppertree - Schinus Polygamus (Cav.) Cabrera
- Hardenbergia Benth.
- Hardgrass - Sclerochloa P. Beauv.
- Hardham's Bedstraw - Galium Hardhamiae Dempster
- Hardham's Evening Primrose - Camissonia Hardhamiae P.H. Raven
- Hardheads - Acroptilon Cass.
- Hardheads - Acroptilon Repens (L.) DC.
- Hardstem Bulrush - Schoenoplectus Acutus (Muhl. ex Bigelow) Á. Löve & D. Löve
- Hardstem Bulrush - Schoenoplectus Acutus (Muhl. ex Bigelow) Á. Löve & D. Löve var. acutus
- Hardstem Lovegrass - Eragrostis Atropioides Hillebr.
- Hardy Fuchsia - Fuchsia Magellanica Lam.
- Hardy Orange - Poncirus Trifoliata (L.) Raf.
- Hardy Swamplily - Crinum Bulbispermum (Burm. f.) Milne-Redhead & Schweickerdt
- Hare Barley - Hordeum Murinum L. ssp. leporinum (Link) Arcang.
- Hare's Ear - Bupleurum Rotundifolium L.
- Hare's Ear Mustard - Conringia Heist. ex Fabr.
- Hare's Ear Mustard - Conringia Orientalis (L.) Dumort.
- Harebell - Asyneuma Griseb. & Schenk
- Hareleaf - Lagophylla Nutt.
- Haresfoot Fern - Davallia Embolostegia Copel.
- Haresfoot Fern - Davallia Heterophylla Sm.
- Haresfoot Fern - Davallia Pectinata Sm.
- Haresfoot Fern - Davallia Pusilla Mett.
- Haresfoot Fern - Davallia Repens (L. f.) Kuhn, nom. cons.
- Haresfoot Grass - Ectrosia Leporina R. Br.
- Haresfoot Locoweed - Oxytropis Lagopus Nutt.
- Haresfoot Locoweed - Oxytropis Lagopus Nutt. var. atropurpurea (Rydb.) Barneby
- Haresfoot Locoweed - Oxytropis Lagopus Nutt. var. conjugans Barneby
- Haresfoot Locoweed - Oxytropis Lagopus Nutt. var. lagopus
- Harestail Grass - Lagurus L.
- Harestail Grass - Lagurus Ovatus L.
- Harford's Oniongrass - Melica Harfordii Bol.
- Harford's Ragwort - Packera Bolanderi (A. Gray) W.A. Weber & Á. Löve var. harfordii (Greenm.) D.K. Tro
- Harford's Sedge - Carex Harfordii Mack.
- Harford's Tree Poppy - Dendromecon Harfordii Kellogg
- Harger's Goldenrod - Solidago Canadensis L. var. hargeri Fernald
- Harkness' Flaxflower - Leptosiphon Harknessii (Curran) J.M. Porter & L.A. Johnson
- Harlequin Annual Lupine - Lupinus Stiversii Kellogg
- Harlequin Blueflag - Iris Versicolor L.
- Harlequin Calicoflower - Downingia Insignis Greene
- Harlequin Dancing-lady Orchid - Tolumnia Variegata (Sw.) G.J. Braem
- Harlequin Dutchman's Pipe - Aristolochia Anguicida Jacq.
- Harlequin Glorybower - Clerodendrum Trichotomum Thunb.
- Harlequin Monkeyflower - Mimulus Whitneyi A. Gray
- Harlequin Phacelia - Phacelia Howelliana N.D. Atwood
- Harlequin Spiralseed - Schistophragma Intermedia (A. Gray) Pennell
- Harlequinbush - Oenothera Hexandra (Ortega) W.L. Wagner & Hoch
- Harlequinbush - Oenothera Hexandra (Ortega) W.L. Wagner & Hoch [excluded] ssp. hexandra
- Harlequinbush - Oenothera Hexandra (Ortega) W.L. Wagner & Hoch ssp. gracilis (Wooton & Standl.) W.L
- Harmal Peganum - Peganum Harmala L.
- Harness' Popcornflower - Plagiobothrys Kingii (S. Watson) A. Gray var. harknessii (Greene) Jeps.
- Harold's Milkvetch - Astragalus Robbinsii (Oakes) A. Gray var. harringtonii (Rydb.) Barneby
- Harp Dandelion - Taraxacum Lyratum (Ledeb.) DC.
- Harp Onefruit - Haplocarpha Lyrata Harr.
- Harpagophytum Dc. ex Meisn.
- Harpalejeunea (spruce) Schiffn.
- Harpalejeunea Ovata (Hook.) Schiffn.
- Harpalejeunea Ovata (Hook.) Schiffn. ssp. integra R.M. Schust.
- Harpalejeunea Stricta (Lindenb. & Gottsche) Steph.
- Harpanthus Drummondii (Taylor) Grolle
- Harpanthus Flotovianus (Nees) Nees
- Harpanthus Nees
- Harpanthus Scutatus (F. Weber & D. Mohr) Spruce
- Harper's Beaksedge - Rhynchospora Harperi Small
- Harper's Beauty - Harperocallis Flava McDaniel
- Harper's Buckwheat - Eriogonum Longifolium Nutt. var. harperi (Goodman) Reveal
- Harper's Dodder - Cuscuta Harperi Small
- Harper's Fimbry - Fimbristylis Perpusilla Harper ex Small & Britton
- Harper's Flax - Linum Sulcatum Riddell var. harperi (Small) C.M. Rogers
- Harper's Heartleaf - Hexastylis Speciosa Harper
- Harper's Searocket - Cakile Edentula (Bigelow) Hook. ssp. harperi (Small) Rodman
- Harper's Sedge - Carex Leptalea Wahlenb. ssp. harperi (Fernald) W. Stone
- Harper's Yelloweyed Grass - Xyris Scabrifolia Harper
- Harperella Fluviatilis Rose
- Harperella Nodosa Rose
- Harperella Vivipara Rose
- Harperocallis - Harperocallis Mcdaniel
- Harpullia - Harpullia Roxb.
- Harrimanella - Harrimanella Coville
- Harrington's Beardtongue - Penstemon Harringtonii Penl.
- Harrington's Cephalotaxus - Cephalotaxus Harringtonia (Knight ex Forbes) K. Koch
- Harris' Dwarf Sand Verbena - Abronia Nana S. Watson var. harrisii S.L. Welsh
- Harris' Goldenrod - Solidago Arguta Aiton var. harrisii (Steele) Cronquist
- Harris' Thelenella Lichen - Thelenella Harrisii H. Mayrh.
- Harrisella Filiformis (Sw.) Cogn.
- Harrisella - Harrisella Fawc. & Rendle
- Harrisia Bonplandii (Parmentier) Britton & Rose
- Harrisia Donae-antoniae M.L. Hooten
- Harrisia Gracilis (Mill.) Britton [excluded]
- Harrison's Barberry - Berberis Harrisoniana Kearney & Peebles
- Harrison's Milkvetch - Astragalus Harrisonii Barneby
- Harrison's Stickseed - Hackelia Patens (Nutt.) I.M. Johnst. var. harrisonii J.L. Gentry
- Harsh Cyanea - Cyanea Scabra Hillebr.
- Harsh Dewberry - Rubus Severus Brainerd
- Harsh Indian Paintbrush - Castilleja Hispida Benth.
- Harsh Indian Paintbrush - Castilleja Hispida Benth. ssp. hispida
- Hart's Lellingeria - Lellingeria Hartii (Jenman) A.R. Sm. & R.C. Moran
- Hart's Ragwort - Packera Hartiana (A. Heller) W.A. Weber & Á. Löve
- Hart's Tonguefern - Asplenium Scolopendrium L.
- Hart's Tonguefern - Asplenium Scolopendrium L. var. americanum (Fernald) Kartesz & Gandhi
- Hartman's Dry Rock Moss - Grimmia Hartmanii Schimp.
- Hartmannia Speciosa (Nutt.) Small
- Hartweg's Alumroot - Heuchera Micrantha Douglas ex Lindl. var. hartwegii (S. Watson ex Wheelock) Rosend.
- Hartweg's Beardtongue - Penstemon Hartwegii Benth.
- Hartweg's Cyphomandra - Cyphomandra Hartwegii (Miers) Dunal
- Hartweg's Doll's-lily - Odontostomum Hartwegii Torr.
- Hartweg's Doll's-lily - Odontostomum Torr.
- Hartweg's Fleabane - Erigeron Foliosus Nutt. var. hartwegii (Greene) Jeps.
- Hartweg's Golden Sunburst - Pseudobahia Bahiifolia (Benth.) Rydb.
- Hartweg's Groundsel - Roldana Hartwegii (Benth.) H. Rob. & Brettel
- Hartweg's Locust - Robinia Viscosa Vent. var. hartwegii (Koehne) Ashe
- Hartweg's Milkvetch - Astragalus Hartwegii Benth.
- Hartweg's Paspalum - Paspalum Hartwegianum Fourn.
- Hartweg's Pricklyleaf - Thymophylla Pentachaeta (DC.) Small var. hartwegii (A. Gray) Strother
- Hartweg's Spineflower - Chorizanthe Pungens Benth. var. hartwegiana Reveal & Hardham
- Hartweg's Sundrops - Calylophus Hartwegii (Benth.) P.H. Raven
- Hartweg's Sundrops - Calylophus Hartwegii (Benth.) P.H. Raven ssp. fendleri (A. Gray) Towner & P.H. Raven
- Hartweg's Sundrops - Calylophus Hartwegii (Benth.) P.H. Raven ssp. filifolius (Eastw.) Towner & P.H. Raven
- Hartweg's Sundrops - Calylophus Hartwegii (Benth.) P.H. Raven ssp. hartwegii
- Hartweg's Sundrops - Calylophus Hartwegii (Benth.) P.H. Raven ssp. pubescens (A. Gray) Towner & P.H. Raven
- Hartweg's Twinevine - Funastrum Cynanchoides (Decne.) Schltr. ssp. heterophyllum (Engelm. ex Torr.) Kartesz
- Hartweg's Umbrellawort - Tauschia Hartwegii (A. Gray) J.F. Macbr.
- Hartweg's Wildginger - Asarum Hartwegii S. Watson
- Hartwrightia - Hartwrightia A. Gray ex S. Watson
- Hartz's Bluegrass - Poa Hartzii Gandog.
- Hartz's Bluegrass - Poa Hartzii Gandog. ssp. hartzii
- Hartz's Bluegrass - Poa Hartzii Gandog. ssp. hartzii var. hartzii
- Hartz's Bluegrass - Poa Hartzii Gandog. ssp. hartzii var. vivipara Polunin
- Harvest Brodiaea - Brodiaea Elegans Hoover
- Harvest Brodiaea - Brodiaea Elegans Hoover ssp. elegans
- Harvestbells - Gentiana Saponaria L.
- Harvestbells - Gentiana Saponaria L. var. latidens House
- Harvestbells - Gentiana Saponaria L. var. saponaria
- Harvestlice - Agrimonia Parviflora Aiton
- Harvey's Beaksedge - Rhynchospora Harveyi W. Boott
- Harvey's Beaksedge - Rhynchospora Harveyi W. Boott var. harveyi
- Harvey's Buttercup - Ranunculus Harveyi (A. Gray) Britton
- Harvey's Hawthorn - Crataegus Harveyana Sarg.
- Harwood's Milkvetch - Astragalus Insularis Kellogg var. harwoodii Munz & McBurney
- Harwood's Woollystar - Eriastrum Harwoodii (T.T. Craig) D. Gowen
- Haspan Flatsedge - Cyperus Haspan L.
- Hasse's Cracked Lichen - Acarospora Hassei Herre
- Hasse's Lecania Lichen - Lecania Hassei (Zahlbr.) W. Noble
- Hasse's Lecidea Lichen - Lecidea Hassei Zahlbr.
- Hasse's Orange Wall Lichen - Xanthoria Hasseana Rasanen
- Hasse's Peltula Lichen - Peltula Obscurans (Nyl.) Gyel. var. hassei (Zahlbr.) Wetmore
- Hasse's Psorotichia Lichen - Psorotichia Hassei Fink
- Hasse's Scribble Lichen - Opegrapha Hassei Zahlbr.
- Hasse's Thelenella Lichen - Thelenella Hassei (Zahlbr.) H. Mayrh.
- Hasse's Thelocarpon Lichen - Thelocarpon Hassei de Lesd.
- Hasse's Vetch - Vicia Hassei S. Watson
- Hassea Lichen - Hassea Bacillosa (Nyl.) Zahlbr.
- Hassea Lichen - Hassea Zahlbr.
- Hasseanthus Blochmaniae (Eastw.) Rose
- Hasseanthus Elongatus Rose
- Hasseanthus Variegatus (S. Watson) Rose
- Hassler's Alternanthera - Alternanthera Hassleriana Chodat ex Chodat & Hassler
- Hassler's Noddingcaps - Triphora Hassleriana (Cogn.) Schltr.
- Hastings Oak - Quercus ×hastingsii Sarg.
- Hastingsia Atropurpurea Becking
- Hastingsia Serpenticola Becking, database artifact
- Hatiora - Hatiora Britton & Rose
- Hato Tejas - Microstachys Corniculata (Vahl) Griseb.
- Hattie Bauer's Halberd Fern - Tectaria Coriandrifolia (Sw.) Underw.
- Hatushima's Bulbophyllum - Bulbophyllum Hatusimanum Tuyama
- Hau Kuahiwi - Hibiscadelphus Bombycinus Forbes
- Haujillo - Havardia Pallens (Benth.) Britton & Rose
- Haupa Mountain Melicope - Melicope Haupuensis (H. St. John) T.G. Hartley & B.C. Stone
- Hauptian Alkaligrass - Puccinellia Distans (Jacq.) Parl. ssp. hauptiana (Trin. ex Krecz.) W.E. Hughes
- Haupu Range Yellow Loosestrife - Lysimachia Haupuensis H. St. John
- Hausa Potato - Solenostemon Rotundifolius (Poir.) J.K. Morton
- Hausknecht's Buckwheat - Eriogonum Umbellatum Torr. var. hausknechtii (Dammer) M.E. Jones
- Haussknecht's Atrichum Moss - Atrichum Haussknechtii Jur. & Milde
- Haussknecht's Clover - Trifolium Haussknechtii Boiss.
- Havaas' Navel Lichen - Umbilicaria Havaasii Llano
- Havana Clustervine - Jacquemontia Havanensis (Jacq.) Urb.
- Havana Nutrush - Scleria Havanensis Britton
- Havana Skullcap - Scutellaria Havanensis Jacq.
- Havana Snakeroot - Ageratina Havanensis (Kunth) R.M. King & H. Rob.
- Havard Oak - Quercus Havardii Rydb.
- Havard Oak - Quercus Havardii Rydb. var. havardii
- Havard Oak - Quercus Havardii Rydb. var. tuckeri S.L. Welsh
- Havard's Buckwheat - Eriogonum Havardii S. Watson
- Havard's Century Plant - Agave Havardiana Trel.
- Havard's Evening Primrose - Oenothera Havardii S. Watson
- Havard's False Willow - Baccharis Havardii A. Gray
- Havard's Fiddleleaf - Nama Havardii A. Gray
- Havard's Gumweed - Grindelia Havardii Steyerm.
- Havard's Ipomopsis - Ipomopsis Havardii (A. Gray) V.E. Grant
- Havard's Panicgrass - Panicum Havardii Vasey
- Havard's Plum - Prunus Havardii (W. Wight) S.C. Mason
- Havard's Stonecrop - Sedum Havardii Rose
- Havard's Threeawn - Aristida Havardii Vasey
- Havardia - Havardia Small
- Havardia Mexicana (Rose) Britton & Rose
- Havardia Sonorae (S. Watson) Britton & Rose
- Hawai'i 'ohe - Tetraplasandra Hawaiensis A. Gray
- Hawai'i Air Fern - Pneumatopteris Sandwicensis (Brack.) Holttum
- Hawai'i Alectryon - Alectryon Macrococcus Radlk.
- Hawai'i Alectryon - Alectryon Macrococcus Radlk. var. auwahiensis G. Linney
- Hawai'i Alectryon - Alectryon Macrococcus Radlk. var. macrococcus
- Hawai'i Beaksedge - Rhynchospora Sclerioides Hook. & Arn.
- Hawai'i Beggarticks - Bidens Hawaiensis A. Gray
- Hawai'i Bentgrass - Agrostis Sandwicensis Hillebr.
- Hawai'i Birdcatching Sedge - Uncinia Uncinata (L. f.) Kük.
- Hawai'i Birdnest Fern - Asplenium Nidus L.
- Hawai'i Blackberry - Rubus Hawaiensis A. Gray
- Hawai'i Blacksnakeroot - Sanicula Sandwicensis A. Gray
- Hawai'i Blue-eyed Grass - Sisyrinchium Acre H. Mann
- Hawai'i Bluegrass - Poa Sandvicensis (Reichart) Hitchc.
- Hawai'i Bog Orchid - Platanthera Holochila (Hillebr.) Kraenzlin
- Hawai'i Bog Violet - Viola Maviensis H. Mann
- Hawai'i Bristle Fern - Trichomanes Draytonianum Brack.
- Hawai'i Brushholly - Xylosma Hawaiiensis Seem.
- Hawai'i Catchfly - Silene Hawaiiensis Sherff
- Hawai'i Cheesewood - Pittosporum Hawaiiense Hillebr.
- Hawai'i Cyrtandra - Cyrtandra Hawaiensis C.B. Clarke
- Hawai'i Delissea - Delissea Fallax Hillebr.
- Hawai'i Desert-thorn - Lycium Sandwicense A. Gray
- Hawai'i Dogweed - Bobea Sandwicensis (A. Gray) Hillebr.
- Hawai'i False Bristlegrass - Dissochondrus Biflorus (Hillebr.) Kuntze ex Hack.
- Hawai'i False Nettle - Boehmeria Grandis (Hook. & Arn.) A. Heller
- Hawai'i False Ohelo - Wikstroemia Phillyreifolia A. Gray
- Hawai'i Fescue - Festuca Hawaiiensis Hitchc.
- Hawai'i Fimbry - Fimbristylis Hawaiiensis Hillebr.
- Hawai'i Greenbrier - Smilax Melastomifolia Sm.
- Hawai'i Hala Pepe - Pleomele Hawaiiensis O. Deg. & I. Deg.
- Hawai'i Hawthorn - Osteomeles Anthyllidifolia (Sm.) Lindl.
- Hawai'i Holly - Ilex Anomala Hook. & Arn.
- Hawai'i Horsenettle - Solanum Sandwicense Hook. & Arn.
- Hawai'i Island Sedge - Oreobolus Furcatus H. Mann
- Hawai'i Jadevine - Strongylodon Ruber Vogel
- Hawai'i Jeweled Orchid - Anoectochilus Sandvicensis Lindl.
- Hawai'i Kauilatree - Alphitonia Ponderosa Hillebr.
- Hawai'i Korthal Mistletoe - Korthalsella Cylindrica (v. Tiegh.) Engl.
- Hawai'i Lady's Nightcap - Bonamia Menziesii A. Gray
- Hawai'i Lopleaf - Cypholophus Moluccanus (Blume) Miq.
- Hawai'i Mirrorplant - Coprosma Cymosa Hillebr.
- Hawai'i Morning-glory - Ipomoea Tuboides O. Deg. & van Ooststr.
- Hawai'i Nutrush - Scleria Testacea Nees
- Hawai'i Olive - Nestegis Sandwicensis (A. Gray) O. Deg. & I. Deg. & L.A.S. Johnson
- Hawai'i Pearls - Caesalpinia Major (Medik.) Dandy & Exell
- Hawai'i Peperomia - Peperomia Latifolia Miq.
- Hawai'i Phyllostegia - Phyllostegia Floribunda Benth.
- Hawai'i Pilo Kea - Platydesma Remyi (Sherff) O. Deg., I. Deg., Sherff & B.C. Stone
- Hawai'i Plantain - Plantago Hawaiensis (A. Gray) Pilg.
- Hawai'i Poisonberry Tree - Pittosporum Argentifolium Sherff
- Hawai'i Pokeweed - Phytolacca Sandwicensis Endl.
- Hawai'i Potato Fern - Marattia Douglasii (C. Presl) Baker
- Hawai'i Pricklyash - Zanthoxylum Hawaiiense Hillebr.
- Hawai'i Pritchardia - Pritchardia Maideniana Becc.
- Hawai'i Quillwort - Isoetes Hawaiiensis W.C. Taylor & W.H. Wagner
- Hawai'i Red Cranesbill - Geranium Arboreum A. Gray
- Hawai'i Rockwort - Nototrichium Sandwicense (A. Gray) Hillebr.
- Hawai'i Roughbush - Streblus Pendulinus (Endl.) F. Muell.
- Hawai'i Scaleseed - Spermolepis Hawaiiensis H. Wolff
- Hawai'i Seagrass - Halophila Hawaiiana Doty & B.C. Stone
- Hawai'i Sedge - Carex Alligata Boott
- Hawai'i Silversword - Argyroxiphium Sandwicense DC.
- Hawai'i Silversword - Argyroxiphium Sandwicense DC. ssp. macrocephalum (A. Gray) Mérat
- Hawai'i Silversword - Argyroxiphium Sandwicense DC. ssp. sandwicense
- Hawai'i Spikemoss - Selaginella Sandvicensis Baker
- Hawai'i Stenogyne - Stenogyne Macrantha Benth.
- Hawai'i Stingingnettle - Hesperocnide Sandwicensis (Weddell) Weddell
- Hawai'i Ticktrefoil - Desmodium Sandwicense E. Mey.
- Hawai'i Treecotton - Kokia Drynarioides (Seem.) Lewt.
- Hawai'i Twinsorus Fern - Diplazium Sandwichianum (C. Presl) Diels
- Hawai'i Umbrella Fern - Sticherus Owhyensis (Hook.) Ching
- Hawai'i Vetch - Vicia Menziesii Spreng.
- Hawai'i Violet - Viola Lanaiensis Becker
- Hawai'i Widelip Orchid - Liparis Hawaiensis H. Mann
- Hawai'i Woodfern - Dryopteris Hawaiiensis (Hillebr.) W.J. Rob.
- Hawai'i Woodnettle - Laportea Interrupta (L.) Chew
- Hawai'i Woodrush - Luzula Hawaiiensis Buchenau
- Hawai'i Woodrush - Luzula Hawaiiensis Buchenau var. glabrata (Hillebr.) O. Deg. & I. Deg.
- Hawai'i Woodrush - Luzula Hawaiiensis Buchenau var. hawaiiensis
- Hawai'i Yelloweyed Grass - Xyris Complanata R. Br.
- Hawai'i Yellowwood - Ochrosia Kilaueaensis H. St. John
- Hawai'ian Buttercup - Ranunculus Hawaiensis A. Gray
- Hawai'ian Cotton - Gossypium Tomentosum Nutt. ex Seem.
- Hawaiian Nadvornikia - Nadvornikia Hawaiensis (Tuck.) Tibell
- Hawk's Eye - Euryops Multifidus (Thunb.) DC.
- Hawkbit - Leontodon L.
- Hawksbeard - Crepis L.
- Hawksworth's Mistletoe - Phoradendron Hawksworthii (Wiens) Wiens
- Hawksworthiana Peltigericola (D. Hawksw.) U. Braun
- Hawksworthiana U. Braun
- Hawkweed Buckwheat - Eriogonum Hieraciifolium Benth.
- Hawkweed - Hieracium L.
- Hawkweed - Hieracium Prenanthoides Vill.
- Hawkweed - Hieracium ×alleghaniense Britton (pro sp.)
- Hawkweed - Hieracium ×atramentarium (Naegeli & Peter) Zahn ex Engl. (pro sp.)
- Hawkweed - Hieracium ×brachiatum Bethel. ex DC.
- Hawkweed - Hieracium ×fassettii Lepage
- Hawkweed - Hieracium ×fassettii Lepage var. fassettii
- Hawkweed - Hieracium ×fassettii Lepage var. mendicum Lepage (pro nm.)
- Hawkweed - Hieracium ×fassettii Lepage var. wisconsinense Lepage (pro nm.)
- Hawkweed - Hieracium ×fernaldii Lepage
- Hawkweed - Hieracium ×flagellare Willd. (pro sp.)
- Hawkweed - Hieracium ×flagellare Willd. var. cernuiforme (Naegeli & Peter) Lepage (pro nm.)
- Hawkweed - Hieracium ×flagellare Willd. var. flagellare
- Hawkweed - Hieracium ×floribundum Wimm. & Grab. (pro sp.)
- Hawkweed - Hieracium ×fuscatrum Naegeli & Peter (pro sp.)
- Hawkweed - Hieracium ×grohii Lepage
- Hawkweed - Hieracium ×grohii Lepage var. farwellii Lepage
- Hawkweed - Hieracium ×grohii Lepage var. grohii
- Hawkweed Oxtongue - Picris Hieracioides L.
- Hawkweed Oxtongue - Picris Hieracioides L. ssp. hieracioides
- Hawkweed Oxtongue - Picris Hieracioides L. ssp. kamtschatica (Ledeb.) Hultén
- Hawkweedleaf Blumea - Blumea Hieraciifolia (Spreng.) DC.
- Haworth's Aeonium - Aeonium Haworthii Webb & Bethel.
- Hawthorn - Crataegus Atrovirens J.B. Phipps & R.J.O. Kennon
- Hawthorn - Crataegus Castlegarensis J.B. Phipps & R.J.O. Kennon
- Hawthorn - Crataegus Enderbyensis J.B. Phipps & R.J.O. Kennon
- Hawthorn - Crataegus L.
- Hawthorn - Crataegus Orbicularis J.B. Phipps & R.J.O. Kennon
- Hawthorn - Crataegus Paludosa Sarg.
- Hawthorn - Crataegus ×brevipes Peck (pro sp.)
- Hawthorn - Crataegus ×haemacarpa Ashe (pro sp.)
- Hawthorn - Crataegus ×hudsonica Sarg. (pro sp.)
- Hawthorn - Crataegus ×immanis Ashe (pro sp.)
- Hawthorn - Crataegus ×incaedua Sarg. (pro sp.)
- Hawthorn - Crataegus ×kennedyi Sarg. (pro sp.)
- Hawthorn - Crataegus ×laneyi Sarg. (pro sp.)
- Hawthorn - Crataegus ×lettermanii Sarg. (pro sp.)
- Hawthorn - Crataegus ×maligna Sarg. (pro sp.)
- Hawthorn - Crataegus ×notha Sarg.
- Hawthorn - Crataegus ×peckietta Sarg. (pro sp.)
- Hawthorn - Crataegus ×pilosa Sarg. (pro sp.)
- Hawthorn - Crataegus ×puberis Sarg. (pro sp.)
- Hawthorn - Crataegus ×rubrocarnea Sarg. (pro sp.)
- Hawthorn - Crataegus ×simulata Sarg.
- Hawthorn - Crataegus ×websteri Sarg.
- Hawthorn - Crataegus ×whittakeri Sarg.
- Hawthorn-leaf Crab Apple - Malus Florentina (Zuccagni) C.K. Schneid.
- Hay Sedge - Carex Argyrantha Tuck.
- Haya Blanca - Guatteria Caribaea Urb.
- Haya Minga - Guatteria Blainii (Griseb.) Urb.
- Haya - Oxandra Laurifolia (Sw.) A. Rich.
- Hayden's Clover - Trifolium Haydenii Porter
- Hayden's Indian Paintbrush - Castilleja Haydenii (A. Gray) Cockerell
- Hayden's Milkvetch - Astragalus Bisulcatus (Hook.) A. Gray var. haydenianus (A. Gray) Barneby
- Hayden's Rimmed Navel Lichen - Rhizoplaca Haydenii (Tuck.) W.A. Weber
- Hayden's Sedge - Carex Haydenii Dewey
- Hayfield Tarweed - Hemizonia Congesta DC.
- Hayfield Tarweed - Hemizonia Congesta DC. ssp. calyculata Babc. & H.M. Hall
- Hayfield Tarweed - Hemizonia Congesta DC. ssp. clevelandii (Greene) Babc. & H.M. Hall
- Hayfield Tarweed - Hemizonia Congesta DC. ssp. congesta
- Hayfield Tarweed - Hemizonia Congesta DC. ssp. leucocephala (Tanowitz) Keil
- Hayfield Tarweed - Hemizonia Congesta DC. ssp. luzulifolia (DC.) Babc. & H.M. Hall
- Hayfield Tarweed - Hemizonia Congesta DC. ssp. tracyi Babc. & H.M. Hall
- Hayfield Tarweed - Hemizonia Congesta DC. ssp. vernalis (D.D. Keck) Tanowitz
- Haynaldia Villosa (L.) Schur
- Hayscented Fern - Dennstaedtia Bernh.
- Hayun Lagu - Serianthes Nelsonii Merr.
- Hazel Alder - Alnus Serrulata (Aiton) Willd.
- Hazel Dodder - Cuscuta Coryli Engelm.
- Hazel Sterculia - Sterculia Foetida L.
- Hazelnut - Corylus L.
- Head Sandmat - Chamaesyce Capitellata (Engelm.) Millsp.
- Headachevine - Clematis Microphylla DC.
- Heal And Draw - Chaptalia Nutans (L.) Polak.
- Healing Croton - Croton Argyranthemus Michx.
- Hearst Ranch Buckbrush - Ceanothus Hearstiorum Hoover & J.B. Roof
- Hearst's Manzanita - Arctostaphylos Hookeri G. Don ssp. hearstiorum (Hoover & J.B. Roof) P.V. Wells
- Heart Of Jesus - Caladium Bicolor (Aiton) Vent.
- Heart-shaped Homalomena - Homalomena Cordata Schott
- Heartleaf Amazonvine - Stigmaphyllon Diversifolium (Kunth) A. Juss.
- Heartleaf Arnica - Arnica Cordifolia Hook.
- Heartleaf Bittercress - Cardamine Cordifolia A. Gray
- Heartleaf Bittercress - Cardamine Cordifolia A. Gray var. cordifolia
- Heartleaf Bittercress - Cardamine Cordifolia A. Gray var. incana A. Gray ex M.E. Jones
- Heartleaf Bittercress - Cardamine Cordifolia A. Gray var. lyallii (S. Watson) A. Nelson & J.F. Macbr.
- Heartleaf Buttercup - Ranunculus Cardiophyllus Hook.
- Heartleaf Cliffbrake - Pellaea Cordifolia (Sessé & Moc.) A.R. Sm.
- Heartleaf Cyrtandra - Cyrtandra Cordifolia Gaudich.
- Heartleaf Evening Primrose - Oenothera Cordata J.W. Loudon
- Heartleaf Fanpetals - Sida Cordata (Burm. f.) Waalkes
- Heartleaf Foamflower - Tiarella Cordifolia L.
- Heartleaf Foamflower - Tiarella Cordifolia L. var. austrina Lakela
- Heartleaf Foamflower - Tiarella Cordifolia L. var. collina Wherry
- Heartleaf Foamflower - Tiarella Cordifolia L. var. cordifolia
- Heartleaf Four O'clock - Mirabilis Nyctaginea (Michx.) MacMill.
- Heartleaf Goldeneye - Viguiera Cordifolia A. Gray
- Heartleaf Groundcherry - Physalis Cordata Mill.
- Heartleaf Hedgenettle - Stachys Cordata Riddell
- Heartleaf Hempvine - Mikania Cordata (Burm. f.) B.L. Rob. [excluded]
- Heartleaf - Hexastylis Raf.
- Heartleaf Horsenettle - Solanum Cardiophyllum Lindl.
- Heartleaf Iceplant - Aptenia Cordifolia (L. f.) Schwant.
- Heartleaf Keckiella - Keckiella Cordifolia (Benth.) Straw
- Heartleaf Madeiravine - Anredera Cordifolia (Ten.) Steenis
- Heartleaf Maiden Fern - Thelypteris Cordata (Fée) Proctor
- Heartleaf Maiden Fern - Thelypteris Cordata (Fée) Proctor var. cordata (Fée) Proctor [excluded]
- Heartleaf Maiden Fern - Thelypteris Cordata (Fée) Proctor var. imitata (C. Chr.) Proctor
- Heartleaf Milkweed - Asclepias Cordifolia (Benth.) Jeps.
- Heartleaf Mock Orange - Philadelphus Cordifolius Lange
- Heartleaf Morning-glory - Ipomoea Cardiophylla A. Gray
- Heartleaf Morning-glory - Ipomoea Cordifolia Carey ex Voight
- Heartleaf Nettle - Urtica Chamaedryoides Pursh
- Heartleaf Noseburn - Tragia Cordata Michx.
- Heartleaf Peppervine - Ampelopsis Cordata Michx.
- Heartleaf Philodendron - Philodendron Cordatum (Vell.) Kunth
- Heartleaf Philodendron - Philodendron Hederaceum (Jacq.) Schott var. oxycardium (Schott) Croat
- Heartleaf Plantain - Plantago Cordata Lam.
- Heartleaf Rosemallow - Hibiscus Martianus Zucc.
- Heartleaf Sandmat - Chamaesyce Cordifolia (Elliott) Small
- Heartleaf Saxifrage - Saxifraga Nelsoniana D. Don
- Heartleaf Saxifrage - Saxifraga Nelsoniana D. Don ssp. carlottae (Calder & Savile) Hultén
- Heartleaf Saxifrage - Saxifraga Nelsoniana D. Don ssp. cascadensis (Calder & Savile) Hultén
- Heartleaf Saxifrage - Saxifraga Nelsoniana D. Don ssp. insularis (Hultén) Hultén
- Heartleaf Saxifrage - Saxifraga Nelsoniana D. Don ssp. nelsoniana
- Heartleaf Skullcap - Scutellaria Ovata Hill
- Heartleaf Skullcap - Scutellaria Ovata Hill ssp. bracteata (Benth.) Epling
- Heartleaf Skullcap - Scutellaria Ovata Hill ssp. mexicana Epling
- Heartleaf Skullcap - Scutellaria Ovata Hill ssp. ovata
- Heartleaf Skullcap - Scutellaria Ovata Hill ssp. pseudoarguta Epling
- Heartleaf Skullcap - Scutellaria Ovata Hill ssp. rugosa (Alph. Wood) Epling
- Heartleaf Skullcap - Scutellaria Ovata Hill ssp. rupestris Epling
- Heartleaf Skullcap - Scutellaria Ovata Hill ssp. venosa Epling
- Heartleaf Speedwell - Veronica Grandis Fisch. ex Spreng.
- Heartleaf Spikemoss - Selaginella Cordifolia (Desv. ex Poir.) Spring
- Heartleaf Springbeauty - Claytonia Cordifolia S. Watson
- Heartleaf Suncup - Camissonia Cardiophylla (Torr.) P.H. Raven
- Heartleaf Suncup - Camissonia Cardiophylla (Torr.) P.H. Raven ssp. cardiophylla
- Heartleaf Suncup - Camissonia Cardiophylla (Torr.) P.H. Raven ssp. robusta (P.H. Raven) P.H. Raven
- Heartleaf Thorn-mint - Acanthomintha Obovata Jeps. ssp. cordata Jokerst
- Heartleaf Twayblade - Listera Cordata (L.) R. Br.
- Heartleaf Twayblade - Listera Cordata (L.) R. Br. var. cordata
- Heartleaf Twayblade - Listera Cordata (L.) R. Br. var. nephrophylla (Rydb.) Hultén
- Heartleaf Twistflower - Streptanthus Cordatus Nutt.
- Heartleaf Twistflower - Streptanthus Cordatus Nutt. var. cordatus
- Heartleaf Twistflower - Streptanthus Cordatus Nutt. var. duranii Jeps.
- Heartleaf Twistflower - Streptanthus Cordatus Nutt. var. piutensis J.T. Howell
- Heartleaf Willow - Salix Cordata Michx.
- Hearts Entangled - Ceropegia Woodii Schltr.
- Heartscale - Atriplex Cordulata Jeps.
- Heartseed - Cardiospermum Microcarpum Kunth
- Heartsepal Buckwheat - Eriogonum Multiflorum Benth.
- Heartshape False Pickerelweed - Monochoria Vaginalis (Burm. f.) C. Presl ex Kunth
- Heartwing Sorrel - Rumex Hastatulus Baldw.
- Heated Phacelia - Phacelia Thermalis Greene
- Heath Bedstraw - Galium Saxatile L.
- Heath Cliffrose - Purshia Ericifolia (Torr. ex A. Gray) Henrickson
- Heath Dog Violet - Viola Canina L. ssp. montana (L.) Hartm.
- Heath - Erica Diaphana Spreng.
- Heath - Erica L.
- Heath False Brome - Brachypodium Pinnatum (L.) P. Beauv.
- Heath Sedge - Carex Flacca Schreb.
- Heath Teatree - Leptospermum Myrsinoides Schltdl.
- Heath Woodrush - Luzula Congesta (Thuill.) Lej.
- Heath Wrightwort - Carlowrightia Linearifolia (Torr.) A. Gray
- Heath-leaf Banksia - Banksia Ericifolia L. f.
- Heather - Calluna Salisb.
- Heather - Calluna Vulgaris (L.) Hull
- Heather Leaf-flower - Phyllanthus Ericoides Torr.
- Heatloving Cracked Lichen - Acarospora Thermophila Herre
- Heavy Sedge - Carex Gravida L.H. Bailey
- Heavy Sedge - Carex Gravida L.H. Bailey var. gravida
- Heavy Sedge - Carex Gravida L.H. Bailey var. lunelliana (Mack.) F.J. Herm.
- Heavyfruit Butterfly Orchid - Encyclia Gravida (Lindl.) Schltr.
- Hebanthe Palmeri S. Watson
- Hebe - Hebe Comm. ex Juss.
- Hebe - Hebe ×franciscana (Eastw.) Souster
- Hebe Venustula (Colenso) Cockayne
- Hecastocleis - Hecastocleis A. Gray
- Hecatonia Scelerata (L.) Fourr.
- Hechtia - Hechtia Klotzsch
- Hechtia Scariosa L.B. Sm.
- Hecistopteris - Hecistopteris J. Sm.
- Heckard's Indian Paintbrush - Castilleja Montigena Heckard
- Heckard's Pepperweed - Lepidium Latipes Hook. var. heckardii Rollins
- Heckner's Lewisia - Lewisia Cotyledon (S. Watson) B.L. Rob. var. heckneri (Morton) Munz
- Heckner's Stonecrop - Sedum Laxum (Britton) A. Berger ssp. heckneri (M. Peck) R.T. Clausen
- Hedeoma Angulata Tharp, ined.?
- Hedeoma Arkansana Nutt.
- Hedeoma Blepharodonta Greene
- Hedeoma Campora Rydb.
- Hedeoma Ciliata Benth.
- Hedeoma Ciliata Nutt.
- Hedeoma Convisae A. Nelson
- Hedeoma Drummondii Benth. var. crenulata Irving
- Hedeoma Drummondii Benth. var. reverchonii A. Gray
- Hedeoma Glabra Nutt.
- Hedeoma Glabrescens (A. Gray) Briq.
- Hedeoma Graveolens Chapm. ex A. Gray
- Hedeoma Incana Torr.
- Hedeoma Lata Small
- Hedeoma Longiflora Rydb.
- Hedeoma Nana (Torr.) Briq. ssp. typica W.S. Stewart
- Hedeoma Ovata A. Nelson
- Hedeoma Piperita Benth. var. oblongifolia A. Gray
- Hedeoma Pulchella Greene
- Hedeoma Sancta Small
- Hedeoma Serpyllifolia Small
- Hedeoma Serpylloides Torr.
- Hedeoma Tenella Hemsl.
- Hedeoma Texana Cory
- Hedeoma Thymoides A. Gray
- Hedeoma Thymoides A. Gray var. oblongifolia (A. Gray) A. Gray
- Hedera Canariensis Willd.
- Hedera Caucasigena Pojark.
- Hedera Helix L. var. hibernica G. Kirchn.
- Hedera Quinquefolia L.
- Hedge Bamboo - Bambusa Multiplex (Lour.) Raeusch. ex Schult. & Schult. f.
- Hedge Cactus - Cereus Hildmannianus K. Schum.
- Hedge False Bindweed - Calystegia Sepium (L.) R. Br.
- Hedge False Bindweed - Calystegia Sepium (L.) R. Br. ssp. americana (Sims) Brummitt
- Hedge False Bindweed - Calystegia Sepium (L.) R. Br. ssp. angulata Brummitt
- Hedge False Bindweed - Calystegia Sepium (L.) R. Br. ssp. erratica Brummitt
- Hedge False Bindweed - Calystegia Sepium (L.) R. Br. ssp. limnophila (Greene) Brummitt
- Hedge False Bindweed - Calystegia Sepium (L.) R. Br. ssp. sepium
- Hedge Maple - Acer Campestre L.
- Hedgehog Cactus - Echinocereus Engelm.
- Hedgehog Gourd - Cucumis Dipsaceus C.G. Ehrenb. ex Spach
- Hedgehog Pricklypoppy - Argemone Squarrosa Greene
- Hedgehog Pricklypoppy - Argemone Squarrosa Greene ssp. glabrata G.B. Ownbey
- Hedgehog Pricklypoppy - Argemone Squarrosa Greene ssp. squarrosa
- Hedgehog Woodrush - Luzula Echinata (Small) F.J. Herm.
- Hedgehyssop - Gratiola L.
- Hedgehyssop - Gratiola Officinalis L.
- Hedgemustard - Sisymbrium L.
- Hedgemustard - Sisymbrium Officinale (L.) Scop.
- Hedgenettle - Stachys L.
- Hedgeparsley - Torilis Adans.
- Hedgerow Geranium - Geranium Pyrenaicum Burm. f.
- Hediondilla - Senna Nitida (Rich.) Irwin & Barneby
- Hedlund's Dot Lichen - Micarea Hedlundii Coppins
- Hedwig's Weissia Moss - Weissia Hedwigii H.A. Crum
- Hedwigia Balsamifera Sw.
- Hedwigia Detonsa (Howe) W.R. Buck & Norris
- Hedwigia Moss - Hedwigia P. Beauv.
- Hedwigia Stellata Hedenäs
- Hedychium Flavum auct. non Roxb.
- Hedyosmum - Hedyosmum Sw.
- Hedyotis Acerosa A. Gray
- Hedyotis Acerosa A. Gray var. bigelovii (Greenm.) W.H. Lewis
- Hedyotis Acerosa A. Gray var. polypremoides (A. Gray) W.H. Lewis
- Hedyotis Angulata Fosberg ex Shinners
- Hedyotis Angusta Fosberg
- Hedyotis Angusta Fosberg var. koolauensis Fosberg
- Hedyotis Angusta Fosberg var. umbrosa Fosberg
- Hedyotis Auricularia L.
- Hedyotis Auricularia L. var. dispersa Fosberg & Sachet
- Hedyotis Australis W.H. Lewis & D.M. Moore
- Hedyotis Biflora (L.) Lam.
- Hedyotis Boscii DC.
- Hedyotis Butterwickiae (Terrell) G.L. Nesom
- Hedyotis Caerulea (L.) Hook.
- Hedyotis Caerulea (L.) Hook. var. minima (Beck) Fosberg
- Hedyotis Caerulea (L.) Hook. var. minor (Michx.) Torr. & A. Gray
- Hedyotis Callitrichoides (Griseb.) W.H. Lewis
- Hedyotis Canadensis (Willd. ex Roem. & Schult.) Fosberg
- Hedyotis Centranthoides (Hook. & Arn.) Steud. var. laevis (Wawra) Fosberg
- Hedyotis Cervantesii Kunth
- Hedyotis Commutata Schult. & Schult. f.
- Hedyotis Correllii W.H. Lewis
- Hedyotis Corymbosa (L.) Lam.
- Hedyotis Crassifolia Raf.
- Hedyotis Crassifolia Raf. var. micrantha Shinners
- Hedyotis Croftiae (Britton & Rusby) Shinners
- Hedyotis Elatior (H. Mann) Fosberg var. ensiformis (Fosberg) Fosberg
- Hedyotis Elatior (H. Mann) Fosberg var. herbacea (Levl.) Fosberg
- Hedyotis Fasciculata Bertol.
- Hedyotis Fluviatilis (Forbes) Fosberg var. hathewayi Fosberg
- Hedyotis Fluviatilis (Forbes) Fosberg var. kamapuaana (O. Deg.) Fosberg
- Hedyotis Fluviatilis (Forbes) Fosberg var. kauaiensis Fosberg
- Hedyotis Foetida Dalzell
- Hedyotis Foetida Dalzell var. mariannensis (Merr.) Fosberg
- Hedyotis Fruticulosa (Volkens) Merr.
- Hedyotis Glaucifolia (A. Gray) Fosberg
- Hedyotis Glaucifolia (A. Gray) Fosberg var. helleri Fosberg
- Hedyotis Glaucifolia (A. Gray) Fosberg var. subimpressa Fosberg
- Hedyotis Glaucifolia (A. Gray) Fosberg var. waimeae (Wawra) Fosberg
- Hedyotis Greenmanii Fosberg
- Hedyotis Halei Torr. & A. Gray
- Hedyotis - Hedyotis Ponapensis Valeton
- Hedyotis Herbacea L.
- Hedyotis Humifusa A. Gray
- Hedyotis Lanceolata Poir.
- Hedyotis Lancifolia Schumach.
- Hedyotis Longifolia (Gaertn.) Hook.
- Hedyotis Longifolia (Gaertn.) Hook. var. ciliolata (Torr.) Mohlenbr.
- Hedyotis Longifolia (Gaertn.) Hook. var. tenuifolia (Nutt.) Torr. & A. Gray
- Hedyotis Mannii Fosberg var. cuspidata Fosberg
- Hedyotis Mannii Fosberg var. munroi Fosberg
- Hedyotis Mannii Fosberg var. scaposa Fosberg
- Hedyotis Megalantha Merr.
- Hedyotis Michauxii Fosberg
- Hedyotis Minima (Beck) Torr. & A. Gray
- Hedyotis Molokaiensis Fosberg
- Hedyotis Mullerae Fosberg
- Hedyotis Nigricans (Lam.) Fosberg
- Hedyotis Nigricans (Lam.) Fosberg var. angulata (Fosberg ex Shinners) W.H. Lewis
- Hedyotis Nigricans (Lam.) Fosberg var. austrotexana B.L. Turner
- Hedyotis Nigricans (Lam.) Fosberg var. filifolia (Chapm.) Shinners
- Hedyotis Nigricans (Lam.) Fosberg var. floridana (Standl.) Wunderlin
- Hedyotis Nigricans (Lam.) Fosberg var. nigricans
- Hedyotis Nigricans (Lam.) Fosberg var. papillacea B.L. Turner
- Hedyotis Nigricans (Lam.) Fosberg var. parviflora (A. Gray) W.H. Lewis
- Hedyotis Nigricans (Lam.) Fosberg var. pulvinata (Small) Fosberg
- Hedyotis Nigricans (Lam.) Fosberg var. rigidiuscula (A. Gray) Shinners
- Hedyotis Nigricans (Lam.) Fosberg var. scabra (S. Watson) Fosberg
- Hedyotis Nuttalliana Fosberg
- Hedyotis Ouachitana E.B. Sm.
- Hedyotis Pentandra K. Schum.
- Hedyotis Polypremoides (A. Gray) Shinners
- Hedyotis Pooleana B.L. Turner
- Hedyotis Procumbens (Walter ex J.F. Gmel.) Fosberg
- Hedyotis Procumbens (Walter ex J.F. Gmel.) Fosberg var. hirsuta W.H. Lewis
- Hedyotis Purpurea (L.) Torr. & A. Gray
- Hedyotis Purpurea (L.) Torr. & A. Gray var. calycosa (A. Gray) Fosberg
- Hedyotis Purpurea (L.) Torr. & A. Gray var. ciliolata (Torr.) Fosberg
- Hedyotis Purpurea (L.) Torr. & A. Gray var. floridana (Standl.) Fosberg
- Hedyotis Purpurea (L.) Torr. & A. Gray var. longifolia (Gaertn.) Fosberg
- Hedyotis Purpurea (L.) Torr. & A. Gray var. montana (Small) Fosberg
- Hedyotis Purpurea (L.) Torr. & A. Gray var. setiscaphia (L.G. Carr) Fosberg
- Hedyotis Purpurea (L.) Torr. & A. Gray var. tenuifolia (Nutt.) Fosberg
- Hedyotis Pygmaea Roem. & Schult.
- Hedyotis Remyi (Hillebr.) Fosberg
- Hedyotis Remyi (Hillebr.) Fosberg var. nuttallii (Fosberg) Fosberg
- Hedyotis Remyi (Hillebr.) Fosberg var. plana (Fosberg) Fosberg
- Hedyotis Remyi (Hillebr.) Fosberg var. silvicola Fosberg
- Hedyotis Rigida Fosberg [excluded]
- Hedyotis Rigida Fosberg var. rigida Fosberg [excluded]
- Hedyotis Rigida Fosberg var. tenuifolia Fosberg [excluded]
- Hedyotis Rosea Raf.
- Hedyotis Rubra (Cav.) A. Gray
- Hedyotis Salina (A. Heller) Shinners
- Hedyotis Salzmannii (DC.) Steud.
- Hedyotis Scabridifolia Kaneh.
- Hedyotis Schlechtendahliana Steud. ssp. rockii Fosberg
- Hedyotis Schlechtendahliana Steud. ssp. tenuifolia Fosberg
- Hedyotis Schlechtendahliana Steud. var. glauca (Meyen) Fosberg
- Hedyotis Schlechtendahliana Steud. var. nitens (Wawra) Fosberg
- Hedyotis Schlechtendahliana Steud. var. nuttallii Fosberg
- Hedyotis Schlechtendahliana Steud. var. opaca (Wawra) Fosberg
- Hedyotis Schlechtendahliana Steud. var. plana Fosberg
- Hedyotis Schlechtendahliana Steud. var. remyi (Hillebr.) Fosberg
- Hedyotis Schlechtendahliana Steud. var. reticulata Fosberg
- Hedyotis Schlechtendahliana Steud. var. schlechtendahliana
- Hedyotis Schlechtendahliana Steud. var. secundiflora (Hillebr.) Fosberg
- Hedyotis Stenophylla Torr. & A. Gray var. parviflora A. Gray
- Hedyotis Strigulosa (Bartlett ex DC.) Fosberg
- Hedyotis Strigulosa (DC.) Fosberg
- Hedyotis Subviscosa (C. Wright ex A. Gray) Shinners
- Hedyotis Tayloriae Fosberg
- Hedyotis Thyrsoidea Fosberg
- Hedyotis Thyrsoidea Fosberg var. hillebrandii Fosberg
- Hedyotis Uniflora (L.) Lam.
- Hedyotis Uniflora (L.) Lam. var. fasciculata (Bertol.) W.H. Lewis
- Hedyotis Verticillata (L.) Lam.
- Hedyotis Wrightii (A. Gray) Fosberg
- Hedypnois - Hedypnois Mill.
- Hedysarum Alpinum L. ssp. americanum (Michx.) Fedtsch.
- Hedysarum Alpinum L. var. alpinum
- Hedysarum Alpinum L. var. americanum Michx.
- Hedysarum Alpinum L. var. grandiflorum Rollins
- Hedysarum Alpinum L. var. philoscia (A. Nelson) Rollins
- Hedysarum Americanum (Michx.) Britton
- Hedysarum Arcticum B. Fedtsch.
- Hedysarum Argenteum M. Bieb., nom. illeg.
- Hedysarum Biebersteinii Chrtkova
- Hedysarum Boreale Nutt. var. cinerascens (Rydb.) Rollins
- Hedysarum Boreale Nutt. var. gremiale (Rollins) Northstrom & S.L. Welsh, database
- Hedysarum Boreale Nutt. var. mackenziei (Richardson) C.L. Hitchc.
- Hedysarum Boreale Nutt. var. obovatum Rollins
- Hedysarum Boreale Nutt. var. pabulare (A. Nelson) Dorn
- Hedysarum Boreale Nutt. var. rivulare (L.O. Williams) Northstrom
- Hedysarum Boreale Nutt. var. typicum Rollins
- Hedysarum Boreale Nutt. var. utahense (Rydb.) Rollins
- Hedysarum Candidum M. Bieb.
- Hedysarum Caucasicum M. Bieb.
- Hedysarum Cinerascens Rydb.
- Hedysarum Cyprium Boiss.
- Hedysarum Flexuosum L.
- Hedysarum Fruticosum Pall.
- Hedysarum Fruticosum Pall. ssp. mongolicum (Turcz.) B. Fedtsch.
- Hedysarum Gemellum Willd. ex Vogel, nom. inval.
- Hedysarum Grandiflorum Walter, non Pall., nom. illeg.
- Hedysarum Gremiale Rollins
- Hedysarum Hedysaroides auct. non (L.) Schinz & Thell.
- Hedysarum Humile L.
- Hedysarum Mackenziei Richardson
- Hedysarum Mackenziei Richardson var. fraseri B. Boivin
- Hedysarum Molle Vahl
- Hedysarum Multijugum Maxim.
- Hedysarum Onobrychis L.
- Hedysarum Pabulare A. Nelson
- Hedysarum Pabulare A. Nelson var. rivulare L.O. Williams
- Hedysarum Pallens (Moris) Hal.
- Hedysarum Pedunculatum Mill.
- Hedysarum Philoscia A. Nelson
- Hedysarum Repens L.
- Hedysarum Sibiricum Poir.
- Hedysarum Spinosissimum L.
- Hedysarum Tauricum Pall. ex Willd.
- Hedysarum Truncatum Eastw.
- Hedysarum Uintahense A. Nelson
- Hedysarum Utahense Rydb.
- Hedysarum Varium Willd.
- Hedysarum Vicioides Turcz.
- Hedysarum Violaceum L.
- Heermann's Bird's-foot Trefoil - Lotus Heermannii (Durand & Hilg.) Greene
- Heermann's Bird's-foot Trefoil - Lotus Heermannii (Durand & Hilg.) Greene var. heermannii
- Heermann's Bird's-foot Trefoil - Lotus Heermannii (Durand & Hilg.) Greene var. orbicularis (A. Gray) Isely
- Heermann's Buckwheat - Eriogonum Heermannii Durand & Hilg.
- Heermann's Buckwheat - Eriogonum Heermannii Durand & Hilg. var. argense (M.E. Jones) Munz
- Heermann's Buckwheat - Eriogonum Heermannii Durand & Hilg. var. heermannii
- Heermann's Buckwheat - Eriogonum Heermannii Durand & Hilg. var. humilius (S. Stokes) Reveal
- Heermann's Buckwheat - Eriogonum Heermannii Durand & Hilg. var. subracemosum (S. Stokes) Reveal
- Heermann's Buckwheat - Eriogonum Heermannii Durand & Hilg. var. subspinosum Reveal
- Heermann's Buckwheat - Eriogonum Heermannii Durand & Hilg. var. sulcatum (S. Watson) Munz & Reveal
- Heermann's Tarweed - Holocarpha Heermannii (Greene) D.D. Keck
- Heim's Desmatodon Moss - Desmatodon Heimii (Hedw.) Mitt.
- Heim's Desmatodon Moss - Desmatodon Heimii (Hedw.) Mitt. var. heimii
- Heimburger's Anemone - Anemone Drummondii S. Watson ssp. heimburgeri Á. Löve & D. Löve
- Heimia - Heimia Link
- Heimia Longipes (A. Gray) Cory
- Heinemann's Andreaea Moss - Andreaea Heinemannii Hampe & Müll. Hal.
- Heisteria Jacq.
- Heisteria Longipes Standl.
- Helanthium Tenellum (Mart. ex Roem. & Schult.) Britton
- Heldreich's Alfalfa - Medicago Heldreichii E. Small
- Heldreich's Clover - Trifolium Heldreichianum (Gibelli & Belli) Hausskn.
- Heleastrum Hemisphericum (Alexander) Shinners
- Helecho Gigante - Cyathea Tenera (J. Sm. ex Hook.) T. Moore
- Helecho Gigante De La Sierra - Alsophila Bryophila R. Tryon
- Helenium Amphilobum A. Gray
- Helenium Apterum (S.F. Blake) Bierner [excluded]
- Helenium Autumnale L. var. canaliculatum (Lam.) Torr. & A. Gray
- Helenium Autumnale L. var. parviflorum (Nutt.) Fernald
- Helenium Badium (A. Gray ex S. Watson) Greene
- Helenium Bigelovii A. Gray var. festivum Jeps.
- Helenium Canaliculatum Lam.
- Helenium Curtisii A. Gray
- Helenium Decurrens (Less.) Vatke, non Moench
- Helenium Fimbriatum auct. non (Michx.) Eaton
- Helenium Floridanum Fernald
- Helenium Godfreyi Fernald
- Helenium Helenium (Nutt.) Small, nom. inval.
- Helenium Hoopesii A. Gray
- Helenium Incisum (Torr. & A. Gray) Alph. Wood
- Helenium Lanciniatum A. Gray [excluded]
- Helenium Latifolium Mill.
- Helenium Macranthum Rydb.
- Helenium Montanum Nutt.
- Helenium Nudiflorum Nutt.
- Helenium Nuttallii A. Gray
- Helenium Ooclinium A. Gray
- Helenium Parviflorum Nutt.
- Helenium Rivulare (Greene) Rydb.
- Helenium Setigerum (DC.) Britton & Rusby
- Helenium Tenuifolium Nutt.
- Helenium Tenuifolium Nutt. var. badium A. Gray ex S. Watson
- Helenium Vernale auct. non Walter
- Heleocharis Flaccida (Rchb.) Urb.
- Heleocharis Flaccida (Rchb.) Urb. var. fuscescens Kük.
- Heleochloa Alopecuroides (Piller & Mitterp.) Host ex Roem.
- Heleochloa Schoenoides (L.) Host ex Roem.
- Helianthella Californica A. Gray var. californica
- Helianthella Californica A. Gray var. nevadensis (Greene) Jeps.
- Helianthella Californica A. Gray var. shastensis W.A. Weber
- Helianthella Covillei A. Nelson
- Helianthella Grandiflora Torr. & A. Gray
- Helianthella - Helianthella Torr. & A. Gray
- Helianthella Pringlei A. Gray
- Helianthella Tenuifolia Torr. & A. Gray
- Helianthemum Aldersonii Greene
- Helianthemum Canadense (L.) Michx. var. sabulonum Fernald
- Helianthemum Capitatum Nutt. ex Engelm. & A. Gray
- Helianthemum Guttatum (L.) Mill.
- Helianthemum Mutabile (Jacq.) Moench
- Helianthemum Nummularium (L.) Mill.
- Helianthemum Scoparium Nutt. var. aldersonii (Greene) Munz
- Helianthemum Scoparium Nutt. var. vulgare Jeps.
- Helianthemum Suffrutescens Schreib.
- Helianthemum Thyrsoideum Barnhart
- Helianthium Parvulum (Engelm.) Britton
- Helianthium Tenellum (Mart. ex Schult. f.) Britton
- Helianthus Alienus E.E. Watson
- Helianthus Angustifolius L. var. planifolius Fernald
- Helianthus Annuus L. ssp. jaegeri (Heiser) Heiser
- Helianthus Annuus L. ssp. lenticularis (Douglas ex Lindl.) Cockerell
- Helianthus Annuus L. ssp. texanus Heiser
- Helianthus Annuus L. var. lenticularis (Douglas ex Lindl.) Steyerm.
- Helianthus Annuus L. var. macrocarpus (DC.) Cockerell
- Helianthus Annuus L. var. texanus (Heiser) Shinners
- Helianthus Aridus Rydb.
- Helianthus Aristatus Elliott
- Helianthus Atrorubens L. var. alsodes Fernald
- Helianthus Atrorubens L. var. pubescens Kuntze
- Helianthus Borealis E.E. Watson
- Helianthus Canescens (A. Gray) S. Watson, nom. inq.
- Helianthus Canus (Britton) Wooton & Standl.
- Helianthus Cinereus Torr. & A. Gray var. sullivantii Torr. & A. Gray
- Helianthus Crenatus R.C. Jacks.
- Helianthus Cucumerifolius Torr. & A. Gray
- Helianthus Dalyi Britton
- Helianthus Debilis Nutt. ssp. hirtus Heiser
- Helianthus Debilis Nutt. ssp. praecox (Engelm. & A. Gray) Heiser
- Helianthus Debilis Nutt. ssp. runyonii Heiser
- Helianthus Debilis Nutt. var. cucumerifolius (Torr. & A. Gray) A. Gray
- Helianthus Debilis Nutt. var. silvestris (Heiser) Cronquist
- Helianthus Debilis Nutt. var. tardiflorus (Heiser) Cronquist
- Helianthus Debilis Nutt. var. vestitus (E.E. Watson) Cronquist
- Helianthus Dentatus Cav.
- Helianthus Deserticola Heiser
- Helianthus Divaricatus L. var. angustifolius Kuntze
- Helianthus Dowellianus M.A. Curtis
- Helianthus Exilis A. Gray
- Helianthus Fascicularis Greene
- Helianthus Filiformis Small
- Helianthus Giganteus L. ssp. alienus (E.E. Watson) R.W. Long
- Helianthus Giganteus L. var. subtuberosus Britton
- Helianthus Grosseserratus M. Martens ssp. maximus R.W. Long
- Helianthus Grosseserratus M. Martens var. hypoleucus A. Gray
- Helianthus Heiseri R.C. Jacks.
- Helianthus Hirsutus Raf. var. stenophyllus Torr. & A. Gray
- Helianthus Hirsutus Raf. var. trachyphyllus Torr. & A. Gray
- Helianthus Instabilis E.E. Watson
- Helianthus Laetiflorus Pers. var. rigidus (Cass.) Fernald
- Helianthus Laetiflorus Pers. var. subrhomboideus (Rydb.) Fernald
- Helianthus Laevis L.
- Helianthus Lenticularis Douglas ex Lindl.
- Helianthus Ludens Shinners
- Helianthus Mollis Lam. var. cordatus S. Watson
- Helianthus Montanus E.E. Watson
- Helianthus Nuttallii Torr. & A. Gray ssp. canadensis R.W. Long
- Helianthus Nuttallii Torr. & A. Gray ssp. coloradensis (Cockerell) R.W. Long
- Helianthus Nuttallii Torr. & A. Gray var. rydbergii (Britton) B. Boivin
- Helianthus Nuttallii Torr. & A. Gray var. subtuberosus (Britton) B. Boivin
- Helianthus Occidentalis Riddell var. dowellianus (M.A. Curtis) Torr. & A. Gray
- Helianthus Occidentalis Riddell var. plantagineus Torr. & A. Gray
- Helianthus Orgyalis DC.
- Helianthus Parishii A. Gray
- Helianthus Pauciflorus Nutt. var. subrhomboideus (Rydb.) Cronquist
- Helianthus Petiolaris Nutt. var. canescens A. Gray
- Helianthus Petiolaris Nutt. var. fallax (Heiser) B.L. Turner
- Helianthus Pilosus Tausch
- Helianthus Praecox Engelm. & A. Gray var. runyonii (Heiser) B.L. Turner
- Helianthus Quinquenervis Hook.
- Helianthus Reindutus (Steele) E.E. Watson
- Helianthus Rigidus (Cass.) Desf.
- Helianthus Rigidus (Cass.) Desf. ssp. laetiflorus (Rydb.) Heiser
- Helianthus Rigidus (Cass.) Desf. ssp. subrhomboideus (Rydb.) Heiser
- Helianthus Rigidus (Cass.) Desf. var. subrhomboideus (Rydb.) Cronquist
- Helianthus Rydbergii Britton
- Helianthus Saxicola Small
- Helianthus Scaberrimus Elliott
- Helianthus Scrophulariifolius Britton
- Helianthus Stenophyllus (Torr. & A. Gray) E.E. Watson
- Helianthus Subrhomboideus Rydb.
- Helianthus Subtuberosus (Britton) Britton
- Helianthus Tephrodes A. Gray
- Helianthus Tomentosus Michx.
- Helianthus Tomentosus auct. non Michx.
- Helianthus Tracheliifolius Mill.
- Helianthus Tuberosus L. var. subcanescens A. Gray
- Helianthus Uniflorus Nutt.
- Helianthus Validus E.E. Watson
- Helianthus Vestitus E.E. Watson
- Helichrysum Bracteatum (Vent.) Andrews
- Helichrysum Petiolatum (L.) DC.
- Heliconia Aurantiaca Ghiesbr. ex Lem. [excluded]
- Heliconia Elongata Griggs
- Heliconia - Heliconia L.
- Heliconia Humilis (Aubl.) Jacq., nom. utique rej.
- Heliconia Pendula Wawra
- Heliconia Wagneriana Peterson
- Helicteres Apetala Jacq.
- Helicteres - Helicteres L.
- Helictotrichon Bromoides (Gouan) C.E. Hubb.
- Helictotrichon Compressum (Heuff.) Henrard
- Helictotrichon Dahuricum (Kom.) Kitagawa [excluded]
- Helictotrichon Hookeri (Scribn.) Henr.
- Helictotrichon Pratense (L.) Besser
- Helictotrichon Pubescens (Huds.) Besser ex Pilg.
- Helictotrichon Scabrivalve (Trin.) G. Tucker
- Helictotrichon Sulcatum (J. Gay ex Delastre) Henrard
- Helictotrichon Versicolor (Vill.) Schult. & Schult. f.
- Helietta - Helietta Tul.
- Heliocarpus - Heliocarpus L.
- Heliograph Peak Fleabane - Erigeron Heliographis G.L. Nesom
- Heliomeris Annua (M.E. Jones) Cockerell
- Heliomeris Porteri (A. Gray) Cockerell
- Heliomeris Tenuifolia A. Gray
- Heliopsis Gracilis Nutt.
- Heliopsis Helianthoides (L.) Sweet ssp. occidentalis T.R. Fisher
- Heliopsis Helianthoides (L.) Sweet ssp. scabra (Dunal) T.R. Fisher
- Heliopsis Helianthoides (L.) Sweet var. solidaginoides (L.) Fernald
- Heliopsis - Heliopsis Pers.
- Heliopsis Minor (Hook.) C. Mohr
- Heliopsis Scabra Dunal
- Heliotrope - Heliotropium L.
- Heliotropium Anchusifolium Poir.
- Heliotropium Angustifolium Torr.
- Heliotropium Antillanum Urb.
- Heliotropium Arguzioides Kar. & Kir.
- Heliotropium Californicum Greene
- Heliotropium Convolvulaceum (Nutt.) A. Gray var. racemosum (Rose & Standl.) I.M. Johnst.
- Heliotropium Crispiflorum Urb.
- Heliotropium Curassavicum L. ssp. oculatum (A. Heller) Thorne
- Heliotropium Horizontale Small
- Heliotropium Inundatum Sw.
- Heliotropium Leavenworthii Torr.
- Heliotropium Parviflorum L.
- Heliotropium Peruvianum L.
- Heliotropium Phyllostachyum Torr.
- Heliotropium Polyphyllum Lehm. var. horizontale (Small) R.W. Long
- Heliotropium Spathulatum Rydb.
- Heliotropium Undulatum Vahl
- Helipterum Roseum (Hook.) Benth.
- Hellebore - Helleborus L.
- Helleborine - Epipactis Zinn
- Helleborus Hyemalis L.
- Heller's Beardtongue - Penstemon Triflorus A. Heller
- Heller's Beardtongue - Penstemon Triflorus A. Heller ssp. integrifolius Pennell
- Heller's Beardtongue - Penstemon Triflorus A. Heller ssp. triflorus
- Heller's Bird's-beak - Cordylanthus Kingii S. Watson ssp. helleri (Ferris) T.I. Chuang & Heckard
- Heller's Bird's-foot Trefoil - Lotus Unifoliolatus (Hook.) Benth. var. helleri (Britton) Kartesz & Gandhi
- Heller's Blazing Star - Liatris Helleri Porter
- Heller's Cieneguillo - Daphnopsis Helleriana Urb.
- Heller's Cudweed - Pseudognaphalium Helleri (Britton) Anderb.
- Heller's Cudweed - Pseudognaphalium Helleri (Britton) Anderb. ssp. helleri
- Heller's Cudweed - Pseudognaphalium Helleri (Britton) Anderb. ssp. micradenium (Weath.) Kartesz
- Heller's Draba - Draba Helleriana Greene
- Heller's Draba - Draba Helleriana Greene var. bifurcata C.L. Hitchc.
- Heller's Draba - Draba Helleriana Greene var. helleriana
- Heller's Draba - Draba Helleriana Greene var. patens (A. Heller) O.E. Schulz
- Heller's Grape - Vitis Cinerea (Engelm.) Engelm. ex Millard var. helleri (L.H. Bailey) M.O. Moo
- Heller's Marbleseed - Onosmodium Helleri Small
- Heller's Plantain - Plantago Helleri Small
- Heller's Rosette Grass - Dichanthelium Oligosanthes (Schult.) Gould
- Heller's Rosette Grass - Dichanthelium Oligosanthes (Schult.) Gould var. oligosanthes
- Heller's Sedge - Carex Helleri Mack.
- Heller's Spurge - Euphorbia Helleri Millsp.
- Helleriella - Helleriella A.d. Hawkes
- Hellroot - Orobanche Minor Sm.
- Helmet Flower - Scutellaria Integrifolia L.
- Helmet Orchid - Cranichis Sw.
- Helminthocarpon Lichen - Helminthocarpon Fée
- Helminthostachys - Helminthostachys Kaulf.
- Helminthotheca Echioides (L.) Holub
- Helocarpon Lichen - Helocarpon Crassipes Th. Fr.
- Helocarpon Lichen - Helocarpon Th. Fr.
- Helodium Moss - Helodium Paludosum (Sull.) Austin
- Helodium Moss - Helodium Warnst.
- Helodium Paludosum (Sull.) Austin var. helodioides (Renauld & Cardot) Grout
- Helonias Asphodeloides L.
- Helonias Graminea Ker Gawl.
- Helonias - Helonias L.
- Helonias Paniculatus Nutt.
- Helonias Tenax Pursh
- Helonias Virescens Kunth
- Helosciadium Nodiflorum (L.) Koch
- Helxine Soleirolii Req.
- Hemerocallis Flava (L.) L.
- Hemerocallis Fulva (L.) L. var. fulva
- Hemerocallis Fulva (L.) L. var. kwanso Regel
- Hemerocallis Fulva (L.) L. var. rosea Stout
- Hemerocallis Japonica (Thunb.) Thunb. 1784, non Thunb. 1794
- Hemerocallis Lancifolia Thunb.
- Hemerocallis Lilioasphodelus L. var. flava L.
- Hemerocallis Lilioasphodelus L. var. major hort.
- Hemerocallis Plantaginea Lam.
- Hemiachyris Glutinosa S. Schauer
- Hemiachyris Texana DC.
- Hemianthus Callitrichoides Griseb.
- Hemianthus Glomeratus (Chapm.) Pennell
- Hemianthus Micranthemoides Nutt.
- Hemicarpha Aristulata (Coville) Smyth
- Hemicarpha Drummondii Nees
- Hemicarpha Micrantha (Vahl) Pax
- Hemicarpha Micrantha (Vahl) Pax var. aristulata Coville
- Hemicarpha Micrantha (Vahl) Pax var. drummondii (Nees) Friedland
- Hemicarpha Micrantha (Vahl) Pax var. minor (Schrad.) Friedland
- Hemicarpha Occidentalis A. Gray
- Hemichaena Fruticosa Benth.
- Hemichaena - Hemichaena Benth.
- Hemidictyum - Hemidictyum C. Presl
- Hemidiodia Ocymifolia (Willd. ex Roem. & Schult.) K. Schum.
- Hemieva Ranunculifolia (Hook.) Raf.
- Hemigraphis - Hemigraphis Nees
- Hemionitis - Hemionitis L.
- Hemiscola Aculeata (L.) Raf.
- Hemitelia Escuquensis Karst.
- Hemitelia Horrida (L.) R. Br. ex Spreng.
- Hemizonia Arida D.D. Keck
- Hemizonia Australis (D.D. Keck) D.D. Keck
- Hemizonia Calyculata (Babc. & H.M. Hall) D.D. Keck
- Hemizonia Clementina Brandegee
- Hemizonia Clevelandii Greene
- Hemizonia Congesta DC. ssp. lutescens (Greene) Babc. & H.M. Hall
- Hemizonia Conjugens D.D. Keck
- Hemizonia Corymbosa (DC.) Torr. & A. Gray
- Hemizonia Corymbosa (DC.) Torr. & A. Gray ssp. corymbosa
- Hemizonia Corymbosa (DC.) Torr. & A. Gray ssp. macrocephala (Nutt.) D.D. Keck
- Hemizonia Douglasii A. Gray
- Hemizonia Fremontii (A. Gray) A. Gray
- Hemizonia Halliana D.D. Keck
- Hemizonia Hispida Greene
- Hemizonia Increscens (H.M. Hall ex D.D. Keck) Tanowitz
- Hemizonia Increscens (H.M. Hall ex D.D. Keck) Tanowitz ssp. foliosa (Hoover) Tanowitz
- Hemizonia Increscens (H.M. Hall ex D.D. Keck) Tanowitz ssp. increscens
- Hemizonia Increscens (H.M. Hall ex D.D. Keck) Tanowitz ssp. villosa Tanowitz
- Hemizonia Laevis (D.D. Keck) D.D. Keck
- Hemizonia Leucocephala Tanowitz
- Hemizonia Lutescens (Greene) D.D. Keck
- Hemizonia Luzulifolia DC.
- Hemizonia Luzulifolia DC. ssp. rudis (Benth.) D.D. Keck
- Hemizonia Luzulifolia DC. ssp. tracyi Babc. & H.M. Hall
- Hemizonia Luzulifolia DC. var. lutescens Greene
- Hemizonia Minthornii Jeps.
- Hemizonia Mohavensis D.D. Keck
- Hemizonia Mollis (A. Gray) A. Gray
- Hemizonia Multicaulis Hook. & Arn.
- Hemizonia Multicaulis Hook. & Arn. ssp. vernalis D.D. Keck
- Hemizonia Multiglandulosa (DC.) A. Gray var. sparsa A. Gray
- Hemizonia Oppositifolia Greene
- Hemizonia Pallida D.D. Keck
- Hemizonia Paniculata A. Gray ssp. increscens H.M. Hall ex D.D. Keck
- Hemizonia Parryi Greene
- Hemizonia Parryi Greene ssp. australis D.D. Keck
- Hemizonia Parryi Greene ssp. congdonii (B.L. Rob. & Greenm.) D.D. Keck
- Hemizonia Parryi Greene ssp. parryi
- Hemizonia Parryi Greene ssp. rudis (Greene) D.D. Keck
- Hemizonia Pauciflora (A. Gray) A. Gray
- Hemizonia Pentactis (D.D. Keck) D.D. Keck
- Hemizonia Pungens (Hook. & Arn.) Torr. & A. Gray
- Hemizonia Pungens (Hook. & Arn.) Torr. & A. Gray ssp. laevis D.D. Keck
- Hemizonia Pungens (Hook. & Arn.) Torr. & A. Gray ssp. maritima (Greene) D.D. Keck
- Hemizonia Pungens (Hook. & Arn.) Torr. & A. Gray ssp. pungens
- Hemizonia Pungens (Hook. & Arn.) Torr. & A. Gray ssp. septentrionalis D.D. Keck
- Hemizonia Pungens (Hook. & Arn.) Torr. & A. Gray var. septentrionalis (D.D. Keck)
- Hemizonia Ramosissima Benth.
- Hemizonia Scabrella E. Drew
- Hemizonia Spicata Greene
- Hemizonia Tenella (Nutt.) A. Gray
- Hemizonia Tracyi (Babc. & H.M. Hall) D.D. Keck
- Hemizonia Truncata (DC.) A. Gray
- Hemlock Dwarf Mistletoe - Arceuthobium Tsugense (Rosend.) G.N. Jones
- Hemlock Dwarf Mistletoe - Arceuthobium Tsugense (Rosend.) G.N. Jones ssp. mertensianae Hawksw. & Nickrent
- Hemlock Dwarf Mistletoe - Arceuthobium Tsugense (Rosend.) G.N. Jones ssp. tsugense
- Hemlock Rosette Grass - Dichanthelium Sabulorum (Lam.) Gould & C.A. Clark
- Hemlock Rosette Grass - Dichanthelium Sabulorum (Lam.) Gould & C.A. Clark var. patulum (Scribn. & Merr.) Gould &
- Hemlock Rosette Grass - Dichanthelium Sabulorum (Lam.) Gould & C.A. Clark var. sabulorum (Lam.) Gould & C.A. Cla
- Hemlock Rosette Grass - Dichanthelium Sabulorum (Lam.) Gould & C.A. Clark var. thinium (Hitchc. & Chase) Gould &
- Hemlock - Tsuga Carrière
- Hemlock Waterparsnip - Sium Suave Walter
- Hemlockparsley - Conioselinum Hoffm.
- Hemp Agrimony - Eupatorium Cannabinum L.
- Hemp Broomrape - Orobanche Ramosa L.
- Hemp - Cannabis L.
- Hempleaf Ragwort - Senecio Cannabinifolius Hook. & Arn.
- Hempnettle - Galeopsis L.
- Hempvine - Mikania Willd.
- Hen And Chickens - Jovibarba Heuffelii (Schott) Á. Löve & D. Löve
- Hen's Eyes - Ardisia Crenata Sims
- Henbane - Hyoscyamus L.
- Henbane - Hyoscyamus Muticus L.
- Henbit Deadnettle - Lamium Amplexicaule L.
- Henderson's Angelica - Angelica Hendersonii J.M. Coult. & Rose
- Henderson's Bentgrass - Agrostis Hendersonii Hitchc.
- Henderson's Biscuitroot - Lomatium Hendersonii (J.M. Coult. & Rose) J.M. Coult. & Rose
- Henderson's Checkerbloom - Sidalcea Hendersonii S. Watson
- Henderson's Currant - Ribes Oxyacanthoides L. ssp. hendersonii (C.L. Hitchc.) Sinnott
- Henderson's Fawnlily - Erythronium Hendersonii S. Watson
- Henderson's Horkelia - Horkelia Hendersonii Howell
- Henderson's Milkvetch - Astragalus Accidens S. Watson var. hendersonii M.E. Jones
- Henderson's Needlegrass - Achnatherum Hendersonii (Vasey) Barkworth
- Henderson's Phlox - Phlox Hendersonii (E.E. Nelson) Cronquist
- Henderson's Sedge - Carex Hendersonii L.H. Bailey
- Henderson's Triteleia - Triteleia Hendersonii Greene
- Henderson's Triteleia - Triteleia Hendersonii Greene var. hendersonii
- Henderson's Wavewing - Pteryxia Hendersonii (J.M. Coult. & Rose) Mathias & Constance
- Henequen - Agave Fourcroydes Lemaire
- Henicodium Moss - Henicodium (müll. Hal.) Kindb.
- Henicodium Moss - Henicodium Geniculatum (Mitt.) W.R. Buck
- Henna - Lawsonia Inermis L.
- Henriettea Triflora auct. non (Vahl) Alain
- Henriettella Fascicularis (Sw.) C. Wright ex Sauvalle
- Henriettella Macfadyenii Triana
- Henriettella Membranifolia Cogn.
- Henriettella Triflora auct. non (Vahl) Triana
- Henrieville Woodyaster - Xylorhiza Confertifolia (Cronquist) T.J. Watson
- Henry Indian Paintbrush - Castilleja Parviflora Bong. var. oreopola (Greenm.) Ownbey
- Henry's Lily - Lilium Henryi Baker
- Henry's Sphagnum - Sphagnum Henryense Warnst.
- Henry's Spiderlily - Hymenocallis Henryae Traub
- Henry's Spiderlily - Hymenocallis Henryae Traub var. glaucifolia J.N. Henry & G. Lom. Sm.
- Henry's Spiderlily - Hymenocallis Henryae Traub var. henryae
- Henry's Spiderlily - Hymenocallis Occidentalis (Leconte) Kunth var. eulae (Shinners) G. Lom. Sm. & Flory
- Henrya Brevifolia Happ
- Henrya - Henrya Nees ex Benth.
- Henson's Calammophila - ×calammophila Don-hensonii Reznicek & E.J. Judziewicz
- Henssen's Map Lichen - Rhizocarpon Hensseniae Brodo
- Hentz's Phlox - Phlox Nivalis Lodd. ex Sweet ssp. hentzii (Nutt.) Wherry
- Hepatica Acuta (Pursh) Britton
- Hepatica Acutiloba DC.
- Hepatica Americana (DC.) Ker Gawl.
- Hepatica Hepatica (L.) Karst., nom. inval.
- Hepatica - Hepatica Mill.
- Hepatica - Hepatica Nobilis Schreb.
- Hepatica Triloba Chaix var. acuta Pursh
- Hepatica Triloba Chaix var. americana DC.
- Hepburn's Sedge - Carex Nardina Fr. var. hepburnii (Boott) Kük.
- Hepp's Cracked Lichen - Acarospora Heppii (Nageli ex Hepp) Nageli ex Körb.
- Heppia Adglutinata (Krempelh.) A. Massal.
- Heppia Bolanderi (Tuck.) Vain.
- Heppia Conchiloba Zahlbr.
- Heppia Deserticola Zahlbr.
- Heppia Despreauxii (Mont.) Tuck.
- Heppia Euploca (Ach.) Vain.
- Heppia Guepinii (Delise) Nyl.
- Heppia Hassei Zahlbr.
- Heppia Leptopholis Nyl. ex Hasse
- Heppia Lichen - Heppia Lutosa (Ach.) Nyl.
- Heppia Lichen - Heppia Nageli
- Heppia Macrospora de Lesd.
- Heppia Placodizans Zahlbr.
- Heppia Polyphylla de Lesd.
- Heppia Polyspora Tuck.
- Heppia Richardsii Herre
- Heppia Terrena Nyl. ex Hasse
- Heppia Tortuosa (Nees) Vain.
- Heppia Virescens (Despr.) Nyl.
- Heppia Zahlbruckneri Hasse
- Heracleum Lanatum Michx.
- Heracleum Sibiricum L.
- Heracleum Sibiricum L. var. angustifolium Jacq. p.p.
- Heracleum Sphondylium L. ssp. montanum (Schleich. ex Gaudin) Briq.
- Heracleum Sphondylium L. var. lanatum (Michx.) Dorn
- Herb Bennet - Geum Urbanum L.
- Herb Of Gilead - Cedronella Canariensis (L.) Willd. ex Webb & Bethel.
- Herb Of Grace - Bacopa Monnieri (L.) Pennell
- Herb Of The Cross - Verbena Officinalis L.
- Herb Of The Cross - Verbena Officinalis L. var. officinalis
- Herb Sophia - Descurainia Sophia (L.) Webb ex Prantl
- Herbaceous Blackberry - Rubus Junceus Blanch.
- Herbaceous Glorytree - Tibouchina Herbacea (DC.) Cogn.
- Herbaceous Penstemon - Penstemon Rydbergii A. Nelson var. oreocharis (Greene) N.H. Holmgren
- Herbaceous Periwinkle - Vinca Herbacea Waldst. & Kit.
- Herbaceous Seepweed - Suaeda Maritima (L.) Dumort.
- Herbaceous Seepweed - Suaeda Maritima (L.) Dumort. ssp. maritima
- Herbert River Cherry - Antidesma Dallachyanum Baill.
- Herbertia Caerulea (Herb.) Herb.
- Herbertia Drummondii (Graham) Small
- Herbertia - Herbertia Sweet
- Herbertus A. Gray
- Herbertus Aduncus (Dicks.) A. Gray
- Herbertus Aduncus (Dicks.) A. Gray ssp. aduncus
- Herbertus Aduncus (Dicks.) A. Gray ssp. tenuis H.A. Mill. & E.B. Scott
- Herbertus Hawaiiensis H.A. Mill.
- Herbertus Himalayanus (Steph.) H.A. Mill.
- Herbertus Sakuraii (Warnst.) S. Hatt.
- Herbertus Sakuraii (Warnst.) S. Hatt. ssp. articus Inoue & Steere
- Herbertus Sakuraii (Warnst.) S. Hatt. ssp. sakuraii
- Herbertus Sendtneri (Nees) Lindb.
- Herbertus Stramineus (Dumort.) Trevis.
- Herbst's Bloodleaf - Iresine Herbstii Hook.
- Herbst's Bur Cucumber - Sicyos Herbstii (H. St. John) Telford
- Herbst's Sandmat - Chamaesyce Herbstii W.L. Wagner
- Herbst's Sedge - Carex Wahuensis C.A. Mey. ssp. herbstii T. Koyama
- Herbwilliam - Ptilimnium Capillaceum (Michx.) Raf.
- Hercules' Club - Zanthoxylum Clava-herculis L.
- Herissantia - Herissantia Medik.
- Heritiera Aiton
- Heritiera Littoralis Dryand.
- Heritiera Longipetiolata Kaneh.
- Herman's Dry Rock Moss - Grimmia Hermanii H.A. Crum
- Herman's Dwarf Rush - Juncus Hemiendytus F.J. Herm.
- Herman's Dwarf Rush - Juncus Hemiendytus F.J. Herm. var. abjectus (F.J. Herm.) Ertter
- Herman's Dwarf Rush - Juncus Hemiendytus F.J. Herm. var. hemiendytus
- Hermannia - Hermannia L.
- Hermaphrodite Flatsedge - Cyperus Hermaphroditus (Jacq.) Standl.
- Hermbstaedtia Elegans Moq.
- Hermbstaedtia - Hermbstaedtia Rchb.
- Hermidium Alipes S. Watson
- Hermidium Alipes S. Watson var. pallidum Ced. Porter
- Hermit Milkvetch - Astragalus Eremiticus Sheldon
- Hernandez's Bluecurls - Trichostema Rubisepalum Elmer
- Hernandia - Hernandia L.
- Hernandia Labyrinthica Tuyama
- Hernando County Noddingcaps - Triphora Surinamensis (Lindl.) Britton
- Herniaria Cinerea DC.
- Herniaria-leaf Spurge - Euphorbia Herniarifolia Willd.
- Herpestis Rotundifolia C.F. Gaertn.
- Herpetica Alata (L.) Raf.
- Herpetineuron Moss - Herpetineuron (müll. Hal.) Cardot
- Herpetineuron Moss - Herpetineuron Toccoae (Sull. & Lesq.) Cardot
- Herpothallon Sanguineum (Sw.) Tobler
- Herpothamnus Crassifolius (Andrews) Small
- Herre's Dimple Lichen - Gyalecta Herrei Vezda
- Herre's Ragged Lichen - Platismatia Herrei (Imshaug) W.L. Culb. & C.F. Culb.
- Herre's Rinodina Lichen - Rinodina Herrei H. Magn.
- Herrea Elongata (Haw.) L. Bolus [excluded]
- Herrea Schwant.
- Herrickia Horrida Wooton & Standl.
- Hertel's Porpidia Lichen - Porpidia Herteliana Gowan
- Herteliana Alaskensis (Nyl.) S. Ekman
- Herteliana P. James
- Hertia Cheirifolia Kuntze
- Hertia Neck.
- Herzodiella Moss - Herzogiella Turfacea (Lindb.) Z. Iwats.
- Herzogiella Moss - Herzogiella Adscendens (Lindb.) Z. Iwats. & Schof.
- Herzogiella Moss - Herzogiella Broth.
- Herzogiella Moss - Herzogiella Striatella (Brid.) Z. Iwats.
- Hesperaloe Engelmannii Krauskopf
- Hesperidanthus Linearifolius (A. Gray) Rydb.
- Hesperis Matronalis L. ssp. candida (Kit.) Hegi & Em. Schmid
- Hesperis Matronalis L. ssp. voronovii (N. Busch) P.W. Ball
- Hesperis Pinnatifidus Michx.
- Hesperochiron Californicus (Benth.) S. Watson var. incanus (Greene) Brand
- Hesperochiron Californicus (Benth.) S. Watson var. watsonianus (Greene) Brand
- Hesperochiron - Hesperochiron S. Watson
- Hesperochiron Lasianthus (Greene) H. St. John
- Hesperochiron Villosulus (Greene) Suksd.
- Hesperochloa Kingii (S. Watson) Rydb.
- Hesperocyparis Arizonica (Greene) Bartel var. nevadensis (Abrams) de Laub.
- Hesperocyparis Goveniana (Gordon) Bartel var. abramsiana (C.B. Wolf) de Laub.
- Hesperocyparis Goveniana (Gordon) Bartel var. pygmaea (Lemmon) de Laub.
- Hesperodoria Hallii (A. Gray) Greene
- Hesperogenia Stricklandii J.M. Coult. & Rose
- Hesperolinon Serpentinum McCarten, nom. inval.
- Hesperolinon Sharsmithiae R. O'Donnell
- Hesperomannia Arborescens A. Gray var. bushiana (O. Deg.) Carlq.
- Hesperomannia Arborescens A. Gray var. swezeyi (O. Deg.) Carlq.
- Hesperomannia Arbuscula Hillebr. ssp. oahuensis (Hillebr.) Carlq.
- Hesperomannia Arbuscula Hillebr. var. pearsallii H. St. John
- Hesperomannia Mauiensis H. St. John
- Hesperomecon Linearis (Benth.) Greene
- Hesperonia Aspera (Greene) Standl.
- Hesperonia Bigelovii (A. Gray) Standl.
- Hesperonia Cedrosensis Standl.
- Hesperonia Tenuiloba (S. Watson) Standl.
- Hesperoscordium Maritimum Torr.
- Hesperoscordum Hyacinthinum Lindl.
- Hesperoscordum Lilacinum (Greene) A. Heller ex Abrams
- Hesperostipa Comata (Trin. & Rupr.) Barkworth var. comata
- Hesperostipa Comata (Trin. & Rupr.) Barkworth var. intermedia (Scribn. & Tweedy) Dor
- Hesperoxalis Trilliifolia (Hook.) Small
- Hesperoyucca - Hesperoyucca (engelm.) Baker
- Hess' Fleabane - Erigeron Hessii G.L. Nesom
- Hesse's Pussypaws - Cistanthe Parryi (A. Gray) Hershkovitz var. hesseae (J.H. Thomas) Kartesz & Gandh
- Hester's Foxtail Cactus - Escobaria Hesteri (Y. Wright) Buxbaum
- Hetaeria - Hetaeria Blume
- Hetch Hetchy Monkeyflower - Mimulus Biolettii Eastw.
- Heteranthelium Hochst. ex Jaub. & Spach
- Heteranthelium Piliferum (Banks & Sol.) Hochst.
- Heteranthera Graminea (Michx.) Vahl
- Heteranthera Liebmannii (Buchenau ex Magnus) Shinners
- Heteranthera Reniformis Ruiz & Pav. var. multiflora Griseb.
- Heterocarpon Lichen - Heterocarpon Müll. Arg.
- Heterocarpon Lichen - Heterocarpon Ochroleucum (Tuck.) Müll. Arg.
- Heterocentron - Heterocentron Hook. & Arn.
- Heterocentron Macrostachyum Naud.
- Heterocladium Heteropteroides Best
- Heterocladium Heteropteroides Best var. filescens Best
- Heterocladium Moss - Heterocladium Dimorphum (Brid.) Schimp.
- Heterocladium Moss - Heterocladium Procurrens (Mitt.) A. Jaeger
- Heterocladium Moss - Heterocladium Schimp.
- Heterocladium Squarrosulum Lindb.
- Heterocodon - Heterocodon Nutt.
- Heterocyphelium Lichen - Heterocyphelium Leucampyx (Tuck.) Vain.
- Heterocyphelium Lichen - Heterocyphelium Vain.
- Heterodermia Barbifera (Nyl.) K.P. Singh
- Heterodermia Boryi (Fée) K.P. Singh & S.R. Singh
- Heterodermia Comosa (Eschw.) Follm. & Redon
- Heterodermia Corallophora (Taylor) Skorepa
- Heterodermia Crocea R.C. Harris
- Heterodermia Domingensis (Ach.) Trevis.
- Heterodermia Japonica (Sato) Swinscow & Krog
- Heterodermia Leucomelaena (L.) Poelt
- Heterodermia Neoluecomelaena (Kurok.) Follmann & Redon
- Heterodermia Podocarpa (Bél.) D.D. Awasthi
- Heterodermia Propagulifera (Vain.) J.P. Dey
- Heterodermia Tremulans (Müll. Arg.) W.L. Culb.
- Heterodraba - Heterodraba Greene
- Heterogaura Heterandra (Torr.) Coville
- Heterogonium C. Presl
- Heterogonium Pinnatum (Copel.) Holttum
- Heteromeles Salicifolia (C. Presl) Abrams
- Heteropappus Altaicus (Willd.) Novopokr.
- Heteropappus Less.
- Heteropholis Cochinchinensis (Lour.) Clayton
- Heteropholis Cochinchinensis (Lour.) Clayton var. cochinchinensis
- Heterophyllium Haldanianum (Grev.) Fleisch.
- Heterophyllium Moss - Heterophyllium (schimp.) Müll. Hal. ex Kindb.
- Heterophyllium Moss - Heterophyllium Affine (Hook.) Fleisch.
- Heterophyllium Nemorosum (Brid.) Kindb.
- Heteropogon Secundus J. Presl
- Heteropteris Fée
- Heteropteris Laurifolia (L.) Juss.
- Heteropterys Syringifolia Griseb.
- Heterospathe Elata Scheff.
- Heterospathe Scheff.
- Heterosperma - Heterosperma Cav.
- Heterotheca Adenolepis (Fernald) H.E. Ahles
- Heterotheca Aspera (Shuttlw. ex Small) Shinners
- Heterotheca Bolanderi (A. Gray) V.L. Harms
- Heterotheca Breweri (A. Gray) Shinners
- Heterotheca Camphorata (Eastw.) Semple
- Heterotheca Correllii (Fernald) H.E. Ahles
- Heterotheca Cruiseana (Dress) V.L. Harms, ined.
- Heterotheca Depressa (Rydb.) Dorn
- Heterotheca Echioides (Benth.) Shinners
- Heterotheca Falcata (Pursh) V.L. Harms
- Heterotheca Fastigiata (Greene) V.L. Harms
- Heterotheca Flexuosa (Nash) V.L. Harms
- Heterotheca Floribunda Benth.
- Heterotheca Floridana (Small) R.W. Long
- Heterotheca Foliosa (Nutt.) Shinners
- Heterotheca Gossypina (Michx.) Shinners
- Heterotheca Graminifolia (Michx.) Shinners
- Heterotheca Graminifolia (Michx.) Shinners var. tenuifolia (Torr.) Gandhi & R.D. Thomas
- Heterotheca Graminifolia (Michx.) Shinners var. tracyi (Small) R.W. Long
- Heterotheca Horrida (Rydb.) V.L. Harms
- Heterotheca Horrida (Rydb.) V.L. Harms ssp. cinerascens (S.F. Blake) Semple
- Heterotheca Hyssopifolia (Nutt.) R.W. Long
- Heterotheca Hyssopifolia (Nutt.) R.W. Long var. gigantea (Small) V.L. Harms
- Heterotheca Hyssopifolia (Nutt.) R.W. Long var. subulata (Small) R.W. Long
- Heterotheca Lamarckii Cass.
- Heterotheca Latifolia Buckley
- Heterotheca Latifolia Buckley var. arkansana Wagenkn.
- Heterotheca Latifolia Buckley var. macgregoris Wagenkn.
- Heterotheca Latisquamea (Pollard) V.L. Harms
- Heterotheca Mariana (L.) Shinners
- Heterotheca Mariana (L.) Shinners ssp. floridana (Small) V.L. Harms
- Heterotheca Mariana (L.) Shinners var. macradenia (Fernald) V.L. Harms
- Heterotheca Microcephala (Small) Shinners
- Heterotheca Nervosa (Willd.) Shinners
- Heterotheca Nervosa (Willd.) Shinners var. microcephala (Small) Shinners ex H.E. Ahl
- Heterotheca Oligantha (Chapm. ex Torr. & A. Gray) V.L. Harms
- Heterotheca Pilosa (Nutt.) Shinners
- Heterotheca Pinifolia (Elliott) H.E. Ahles
- Heterotheca Psammophila Wagenkn.
- Heterotheca Ruthii (Small) V.L. Harms
- Heterotheca Scabra (Pursh) DC.
- Heterotheca Scabrella (Torr. & A. Gray) V.L. Harms
- Heterotheca Subaxillaris (Lam.) Britton & Rusby var. latifolia (Buckley) Gandhi & R.D. Th
- Heterotheca Subaxillaris (Lam.) Britton & Rusby var. petiolaris Benke
- Heterotheca Subaxillaris (Lam.) Britton & Rusby var. procumbens Wagenkn.
- Heterotheca Subaxillaris (Lam.) Britton & Rusby var. psammophila (Wagenkn.) Gandhi
- Heterotheca Subulata (Small) V.L. Harms, ined.
- Heterotheca Trichophylla (Nutt.) Shinners
- Heterotheca Villosa (Pursh) Shinners var. angustifolia (Rydb.) Semple
- Heterotheca Villosa (Pursh) Shinners var. camporum (Greene) Wunderlin
- Heterotheca Villosa (Pursh) Shinners var. hispida (Hook.) V.L. Harms
- Heterotheca Villosa (Pursh) Shinners var. horrida (Hook.) Semple
- Heterotheca Villosa (Pursh) Shinners var. shevockii Semple
- Heterotheca Wisconsinensis (Shinners) Shinners
- Heterotrichum Angustifolium DC., nom. illeg.
- Heterotrichum Cymosum (Wendl. ex Spreng.) Urb.
- Heuchera Aceroides Rydb.
- Heuchera Americana L. var. brevipetala Rosend., Butters & Lakela
- Heuchera Americana L. var. calycosa (Small) Rosend., Butters & Lakela
- Heuchera Americana L. var. caroliniana Rosend., Butters & Lakela
- Heuchera Americana L. var. heteradenia Fernald
- Heuchera Americana L. var. interior Rosend., Butters & Lakela
- Heuchera Americana L. var. subtruncata Fernald
- Heuchera Arkansana Rydb.
- Heuchera Calycosa Small
- Heuchera Cespitosa Eastw., orth. var.
- Heuchera Crinita Rydb.
- Heuchera Curtisii Torr. & A. Gray ex A. Gray
- Heuchera Curtisii Torr. & A. Gray ex A. Gray var. crenata Rydb.
- Heuchera Cusickii Rosend., Butters & Lakela
- Heuchera Cylindrica Douglas ex Hook. var. ovalifolia (Nutt. ex Torr. & A. Gray) Whee
- Heuchera Cylindrica Douglas ex Hook. var. suksdorfii (Rydb.) Dorn
- Heuchera Diversifolia Rydb.
- Heuchera Glabella Torr. & A. Gray
- Heuchera Hirsuticaulis (Wheelock) Rydb.
- Heuchera Hispida Pursh
- Heuchera Hispida auct. non Pursh
- Heuchera Lancipetala Rydb.
- Heuchera Leptomeria Greene
- Heuchera Leptomeria Greene var. peninsularis Rosend., Butters & Lakela
- Heuchera Longiflora Rydb. var. aceroides (Rydb.) Rosend., Butters & Lakela
- Heuchera Macrorhiza Small
- Heuchera Micrantha Douglas ex Lindl. var. pacifica Rosend., Butters & Lakela
- Heuchera Missouriensis Rosend.
- Heuchera Nivalis Rosend., Butters & Lakela
- Heuchera Ovalifolia Nutt. ex Torr. & A. Gray
- Heuchera Ovalifolia Nutt. ex Torr. & A. Gray var. orbicularis Rosend., Butters & Lak
- Heuchera Ovalifolia Nutt. ex Torr. & A. Gray var. thompsonii Rosend., Butters & Lake
- Heuchera Parviflora Bartlett var. rugelii (Shuttlw.) Rosend., Butters & Lakela
- Heuchera Parvifolia Nutt. ex Torr. & A. Gray var. dissecta M.E. Jones
- Heuchera Pringlei Rydb.
- Heuchera Puberula Mack. & Bush
- Heuchera Pubescens Pursh var. brachyandra Rosend., Butters & Lakela
- Heuchera Racemosa S. Watson
- Heuchera Richardsonii R. Br. var. affinis Rosend., Butters & Lakela
- Heuchera Richardsonii R. Br. var. grayana Rosend., Butters & Lakela
- Heuchera Richardsonii R. Br. var. hispidior Rosend., Butters & Lakela
- Heuchera Rubescens Torr. var. pachypoda (Greene) Rosend., Butters & Lakela
- Heuchera Saxicola E.E. Nelson
- Heuchera Scabra Rydb.
- Heuchera Suksdorfii Rydb.
- Heuchera Tenuifolia (Wheelock) Rydb.
- Heuchera Versicolor Greene
- Heuchera Versicolor Greene var. leptomeria (Greene) Kearney & Peebles
- Heuchera Villosa Michx. var. intermedia Rosend., Butters & Lakela
- Heuchera Villosa Michx. var. macrorhiza (Small) Rosend., Butters & Lakela
- Heufler's Cracked Lichen - Acarospora Heufleriana Körb.
- Hevea - Hevea Aubl.
- Hexalectris Revoluta Correll var. colemanii Catling
- Hexalectris Spicata (Walter) Barnhart var. arizonica (S. Watson) Catling & Engel
- Hexastylis Memmingeri (Ashe) Small
- Hexastylis Ruthii (Ashe) Small
- Heyderia Decurrens (Torr.) K. Koch
- Heylandia Latebrosa auct.
- Hians Goosefoot - Chenopodium Hians Standl.
- Hibberson's Trillium - Trillium Ovatum Pursh ssp. ovatum var. hibbersonii (T.M.C. Taylor & Szczaw.) G.W
- Hibiscadelphus - Hibiscadelphus Rock
- Hibiscadelphus - Hibiscadelphus ×puakuahiwi K. Baker & S. Allen
- Hibiscus Abelmoschus L.
- Hibiscus Archeri W. Watson
- Hibiscus Arnottianus A. Gray var. punaluuensis (Skottsb.) O. Deg. & I. Deg.
- Hibiscus Brackenridgei A. Gray var. mokuleianus M.J. Roe
- Hibiscus Brackenridgei A. Gray var. molokaianus Rock ex Caum
- Hibiscus Brasiliensis L., nom. utique rej.
- Hibiscus Californicus Kellogg
- Hibiscus Cardiophyllus A. Gray
- Hibiscus Coulteri Harv. ex A. Gray var. brevipedunculatus M.E. Jones
- Hibiscus Cubensis A. Rich.
- Hibiscus Denudatus Benth. var. involucellatus A. Gray
- Hibiscus Eetveldeanus De Wild. & Durand
- Hibiscus Esculentus L.
- Hibiscus - Hibiscus Lunariifolius Willd.
- Hibiscus Immaculatus Roe
- Hibiscus Incanus Wendl. f.
- Hibiscus Kahilii Forbes
- Hibiscus Kokio Hillebr. ex Wawra var. pekeloi O. Deg. & I. Deg.
- Hibiscus Kokio Hillebr. ex Wawra var. pukoonis Caum
- Hibiscus Lambertianus Kunth
- Hibiscus Lasiocarpos Cav. var. occidentalis (Torr.) A. Gray
- Hibiscus Leucophyllus Shiller
- Hibiscus Manihot L.
- Hibiscus Militaris Cav.
- Hibiscus Moscheutos L. ssp. incanus (Wendl. f.) H.E. Ahles
- Hibiscus Moscheutos L. ssp. lasiocarpos (Cav.) O.J. Blanch.
- Hibiscus Moscheutos L. ssp. moscheutos
- Hibiscus Moscheutos L. ssp. palustris (L.) R.T. Clausen
- Hibiscus Moscheutos L. var. occidentalis Torr.
- Hibiscus Moscheutos L. var. purpurascens Sweet
- Hibiscus Newhousei Roe
- Hibiscus Oahuensis O. Deg. & I. Deg.
- Hibiscus Oculiroseus Britton
- Hibiscus Opulifolius Greene
- Hibiscus Palustris L.
- Hibiscus Patersonius Andrews
- Hibiscus Pilosus auct. non (Sw.) Fawc. & Rendle
- Hibiscus Pinetorum Greene
- Hibiscus Platanoides Greene
- Hibiscus Rockii O. Deg. & I. Deg.
- Hibiscus Roeatae H. St. John
- Hibiscus Rosa-sinensis L. var. schizopetalus Dyer
- Hibiscus Saintjohnianus Roe
- Hibiscus Scaber Michx.
- Hibiscus Semilobatus Chapm.
- Hibiscus Ula O. Deg. & I. Deg.
- Hibiscus Waimeae A. Heller var. hannerae O. Deg. & I. Deg.
- Hibiscus Youngianus Gaudich. ex Hook. & Arn.
- Hicaquillo - Dendropemon Sintenisii Krug & Urb.
- Hickman's Checkerbloom - Sidalcea Hickmanii Greene ssp. hickmanii
- Hickman's Cinquefoil - Potentilla Hickmanii Eastw.
- Hickman's Knotweed - Polygonum Hickmanii H. Hinds & R. Morgan
- Hickman's Onion - Allium Hickmanii Eastw.
- Hickman's Popcornflower - Plagiobothrys Chorisianus (Cham.) I.M. Johnst. var. hickmanii (Greene) I.M. Johnst.
- Hicoria Alba Britton p.p.
- Hicoria Aquatica (Michx. f.) Britton
- Hicoria Arkansana (Sarg.) Ashe
- Hicoria Austrina Small
- Hicoria Borealis Ashe
- Hicoria Carolinae-septentrionalis Ashe
- Hicoria Cordiformis (Wangenh.) Britton
- Hicoria Floridana (Sarg.) Sudw.
- Hicoria Glabra (Mill.) Britton
- Hicoria Glabra (Mill.) Britton var. hirsuta Ashe
- Hicoria Laciniosa (Michx. f.) Sarg.
- Hicoria Myristiciformis (Michx. f.) Britton
- Hicoria Ovalis (Wangenh.) Ashe
- Hicoria Ovata (Mill.) Britton
- Hicoria Pallida Ashe
- Hicoria Pecan (Marshall) Britton
- Hicoria Texana Leconte
- Hicoria Texana auct. non Leconte
- Hicoria Tomentosa (Lam.) Raf.
- Hicoria Villosa (Sarg.) Ashe
- Hicriopteris Pinnata (Kunze) Ching
- Hidden Buckwheat - Eriogonum Capistratum Reveal
- Hidden Buckwheat - Eriogonum Capistratum Reveal var. capistratum
- Hidden Orchid - Maxillaria Crassifolia (Lindl.) Rchb. f.
- Hidden Phacelia - Phacelia Inconspicua Greene
- Hidden Spikemoss - Selaginella Eclipes W.R. Buck
- Hidden Tomophyllum - Tomophyllum Inconspicuum (Blume) Parris
- Hiddenflower Phacelia - Phacelia Cryptantha Greene
- Hiddenfruit Bladderwort - Utricularia Geminiscapa Benj.
- Hiddenpetal Indian Mallow - Abutilon Eremitopetalum Caum
- Hideseed - Eucrypta Nutt.
- Hieracium Abscissum Less.
- Hieracium Acranthophorum Om.
- Hieracium Acranthophorum Om. var. isortoquense Böcher
- Hieracium Acuminatum Jord.
- Hieracium Albertinum Farr
- Hieracium Angmagssalikense Om.
- Hieracium Argutum Nutt. var. parishii (A. Gray) Jeps.
- Hieracium Argyraeum Small
- Hieracium Auricula L. p.p.
- Hieracium Canadense Michx. var. fasciculatum (Pursh) Fernald
- Hieracium Canadense Michx. var. hirtirameum Fernald
- Hieracium Canadense Michx. var. kalmii (L.) Scoggan
- Hieracium Canadense Michx. var. subintegrum Lepage
- Hieracium Chapacanum Zahn
- Hieracium Columbianum Rydb.
- Hieracium Columbianum auct. non Rydb.
- Hieracium Crepidispermum Fr.
- Hieracium Cusickii Gandog.
- Hieracium Cynoglossoides Arv.-Touv. var. nudicaule A. Gray
- Hieracium Devoldii Om.
- Hieracium Eugenii Om.
- Hieracium Flagellare Willd. ssp. cernuiforme Naegeli & Peter
- Hieracium Flagellare Willd. ssp. glatzense Naegeli & Peter
- Hieracium Flettii H. St. John & Warren
- Hieracium Florentinum All.
- Hieracium Gracile Hook. var. densifloccosum (Zahn) Cronquist
- Hieracium Gronovii L. var. foliosum Michx.
- Hieracium Helleri Gandog.
- Hieracium Kalmii L. var. canadense (Michx.) Reveal
- Hieracium Musartutense Om.
- Hieracium Nepiocratum Om.
- Hieracium Nudicaule (A. Gray) A. Heller
- Hieracium Parryi Zahn
- Hieracium Pennsylvanicum Fr.
- Hieracium Pratense Tausch
- Hieracium Rigorosum (Laest.) Almquist
- Hieracium Rigorosum (Laest.) Almquist var. nanusekense Om.
- Hieracium Rigorosum (Laest.) Almquist var. sermilikense Om.
- Hieracium Rigorosum (Laest.) Almquist var. unanakense Om.
- Hieracium Scabriusculum Schwein.
- Hieracium Scabriusculum Schwein. var. columbianum (Rydb.) Lepage
- Hieracium Scabriusculum Schwein. var. columbianum auct. non (Rydb.) Lepage
- Hieracium Scabriusculum Schwein. var. perhirsutum Lepage
- Hieracium Scabriusculum Schwein. var. saximontanum Lepage
- Hieracium Scabriusculum Schwein. var. scabrum (Schwein.) Lepage
- Hieracium Scouleri Hook. var. griseum (Rydb.) A. Nelson
- Hieracium Siskiyouense M. Peck
- Hieracium Stiptocaule Om.
- Hieracium Traillii Greene
- Hieracium Triste Willd. ex Spreng. ssp. gracile (Hook.) Calder & Roy L. Taylor
- Hieracium Triste Willd. ex Spreng. var. gracile (Hook.) A. Gray
- Hieracium Triste Willd. ex Spreng. var. tritiforme Zahn
- Hieracium Umbellatum L. var. canadense (Michx.) Breitung
- Hieracium Umbellatum L. var. scabriusculum Farw.
- Hieracium Ungavense Lepage
- Hieracium Vagum Jord.
- Hieracium Venosum L. var. nudicaule (Michx.) Farw.
- Hieracium Vulgatum Fr.
- Hieracium Wrightii (A. Gray) B.L. Rob. & Greenm.
- Hieracium ×dorei Lepage
- Hieracium ×duplex Peter
- Hieracium ×flagellare Willd. var. glatzense (Naegeli & Peter) Lepage [excluded]
- Hieracium ×macrostolonum G. Schneid.
- Hieracium ×marianum Willd. (pro sp.), database artifact
- Hieracium ×scribneri Small (pro sp.), database artifact
- Hierba Del Sapo - Eryngium Nasturtiifolium Juss. ex Delar. f.
- Hierba Del Soldado - Melochia Umbellata (Houtt.) Stapf
- Hierochloe Alpina (Sw. ex Willd.) Roem. & Schult.
- Hierochloe Alpina (Sw. ex Willd.) Roem. & Schult. ssp. alpina
- Hierochloe Alpina (Sw. ex Willd.) Roem. & Schult. ssp. orthantha (T.J. Sørensen) G
- Hierochloe Alpina (Sw. ex Willd.) Roem. & Schult. var. orthantha (T.J. Sørensen) H
- Hierochloe Fragrans (Willd.) Roem. & Schult.
- Hierochloe Macrophylla Thurb. ex Bol.
- Hierochloe Monticola (Bigelow) Á. Löve & D. Löve, non Mez
- Hierochloe Nashii (E.P. Bicknell) Kaczmarek
- Hierochloe Odorata (L.) P. Beauv. ssp. arctica (J. Presl) Tzvelev
- Hierochloe Odorata (L.) P. Beauv. ssp. dahurica (Trin.) Printz [excluded]
- Hierochloe Odorata (L.) P. Beauv. ssp. hirta (Schrank) Tzvelev
- Hierochloe Odorata (L.) P. Beauv. var. fragrans (Willd.) K. Richt.
- Hierochloe Odorata auct. non (L.) P. Beauv. p.p.
- Hierochloe Orthantha T.J. Sørensen
- Higgins' Beardtongue - Penstemon Leonardii Rydb. var. higginsii Neese
- Higgins' Milkvetch - Astragalus Lentiginosus Douglas ex Hook. var. higginsii S.L. Welsh & Thorne
- Higgins' Springparsley - Cymopterus Acaulis (Pursh) Raf. var. higginsii (S.L. Welsh) Goodrich
- Higgins's Phacelia - Phacelia Higginsii N.D. Atwood
- High Mallow - Malva Sylvestris L.
- High Mountain Cinquefoil - Potentilla Flabellifolia Hook. ex Torr. & A. Gray
- High Mountain Penstemon - Penstemon Flavescens Pennell
- High Northern Buttercup - Ranunculus Hyperboreus Rottb.
- High Plains Goldenrod - Solidago Altiplanities C.E.S. Taylor & R.J. Taylor
- High Sierra Phlox - Phlox Dispersa Sharsm.
- High-climbing Jointfir - Ephedra Altissima Desf.
- High-plains Beeblossom - Oenothera Cinerea (Wooton & Standl.) W.L. Wagner & Hoch
- High-plains Beeblossom - Oenothera Cinerea (Wooton & Standl.) W.L. Wagner & Hoch ssp. cinerea
- Highbush Blackberry - Rubus Ostryifolius Rydb.
- Highbush Blueberry - Vaccinium Corymbosum L.
- Highland Doghobble - Leucothoe Fontanesiana (Steud.) Sleumer
- Highland Rush - Juncus Trifidus L.
- Highlands Scrub St. Johnswort - Hypericum Cumulicola (Small) P. Adams
- Higuerillo - Vitex Divaricata Sw.
- Higuerito - Crescentia Linearifolia Miers
- Higuerito De Sierra - Schlegelia Brachyantha Griseb.
- Higuero De Sierra - Crescentia Portoricensis Britton
- Higuillo De Hoja Menuda - Piper Aduncum L.
- Higuillo De Limon - Piper Amalago L.
- Higuillo - Piper Dilatatum Rich.
- Hiiaka - Melicope Feddei (Levl.) T.G. Hartley & B.C. Stone
- Hilaria Cenchroides Kunth [excluded]
- Hilaria Jamesii (Torr.) Benth.
- Hilaria Mutica (Buckley) Benth.
- Hilaria Rigida (Thurb.) Benth. ex Scribn.
- Hilend's Bedstraw - Galium Hilendiae Dempster & Ehrend.
- Hilend's Bedstraw - Galium Hilendiae Dempster & Ehrend. ssp. hilendiae
- Hilgard's Suncup - Camissonia Hilgardii (Greene) P.H. Raven
- Hill Buckwheat - Eriogonum Collinum S. Stokes ex M.E. Jones
- Hill Cane - Arundinaria Appalachiana Triplett, Weakley, & L.G. Clark
- Hill Country Silverbush - Argythamnia Aphoroides Müll. Arg.
- Hill Suncup - Camissonia Graciliflora (Hook. & Arn.) P.H. Raven
- Hill's Lupine - Lupinus Hillii Greene
- Hill's Lupine - Lupinus Hillii Greene var. arizonicus (C.P. Sm.) Harmon
- Hill's Lupine - Lupinus Hillii Greene var. hillii
- Hill's Pondweed - Potamogeton Hillii Morong
- Hill's Thistle - Cirsium Hillii (Canby) Fernald
- Hillebrand's Dubautia - Dubautia Linearis (Gaudich.) D.D. Keck ssp. hillebrandii (H. Mann) G.D. Carr
- Hillebrand's Flatsedge - Cyperus Hillebrandii Boeckeler
- Hillebrand's Flatsedge - Cyperus Hillebrandii Boeckeler var. decipiens (Hillebr.) Kük.
- Hillebrand's Flatsedge - Cyperus Hillebrandii Boeckeler var. hillebrandii
- Hillebrand's Ha'a - Antidesma Platyphyllum H. Mann var. hillebrandii Pax & K. Hoffm.
- Hillebrand's Hollyfern - Polystichum Hillebrandii Carruthers
- Hillebrand's Phyllostegia - Phyllostegia Hillebrandii H. Mann ex Hillebr.
- Hillebrandia - Hillebrandia Oliv.
- Hillegrand's Reedgrass - Calamagrostis Hillebrandii (Munro ex Hillebr.) Hitchc.
- Hillia - Hillia Jacq.
- Hillman's Panicgrass - Panicum Hillmanii Chase
- Hillman's Silverscale - Atriplex Hillmanii (M.E. Jones) Standl.
- Hillman's Stinkweed - Cleomella Hillmanii A. Nelson
- Hillsborough Blackberry - Rubus Ucetanus L.H. Bailey
- Hillside Broomrape - Orobanche Vallicola (Jeps.) Heckard
- Hillside Clermontia - Clermontia Lindseyana Rock
- Hillside Clover Ash - Tetrazygia Crotonifolia (Desr.) DC.
- Hillside Crowngrass - Paspalum Clavuliferum C. Wright
- Hillside False Bindweed - Calystegia Subacaulis Hook. & Arn.
- Hillside False Bindweed - Calystegia Subacaulis Hook. & Arn. ssp. episcopalis Brummitt
- Hillside False Bindweed - Calystegia Subacaulis Hook. & Arn. ssp. subacaulis
- Hillside False Ohelo - Wikstroemia Uva-ursi A. Gray
- Hillside False Ohelo - Wikstroemia Uva-ursi A. Gray var. uva-ursi
- Hillside Gooseberry - Ribes Californicum Hook. & Arn.
- Hillside Gooseberry - Ribes Californicum Hook. & Arn. var. californicum
- Hillside Gooseberry - Ribes Californicum Hook. & Arn. var. hesperium (McClatchie) Jeps.
- Hillside Milkvetch - Astragalus Collinus Douglas ex G. Don
- Hillside Milkvetch - Astragalus Collinus Douglas ex G. Don var. collinus
- Hillside Vervain - Verbena Neomexicana (A. Gray) Small
- Hillside Vervain - Verbena Neomexicana (A. Gray) Small var. hirtella L.M. Perry
- Hillside Vervain - Verbena Neomexicana (A. Gray) Small var. neomexicana
- Hillside Vervain - Verbena Neomexicana (A. Gray) Small var. xylopoda L.M. Perry
- Hillside Woodland-star - Lithophragma Heterophyllum (Hook. & Arn.) Torr. & A. Gray
- Hilly Sandwort - Arenaria Benthamii Fenzl ex Torr. & A. Gray
- Hillyhock - Callaeum Macropterum (DC.) D.M. Johnson, nom. inq.
- Hilo Murainagrass - Ischaemum Byrone (Trin.) Hitchc.
- Hilograss - Paspalum Conjugatum P.J. Bergius
- Hilpertia Scotteri (R.H. Zander & Steere) R.H. Zander
- Himalaya Fishscale Lichen - Psora Himalayana (Bab.) Timdal
- Himalayan Berry - Rubus Bifrons Vest ex Tratt.
- Himalayan Blackberry - Rubus Armeniacus Focke
- Himalayan Cypress - Cupressus Torulosa D. Don
- Himalayan Fleabane - Erigeron Multiradiatus (Lindl. ex DC.) Benth. ex C.B. Clarke
- Himalayan Foothill Borinda - Borinda Fungosa (T.P. Yi) C.M.A. Stapleton
- Himalayan Hazelnut - Corylus Ferox Wall.
- Himalayan Hazelnut - Corylus Ferox Wall. var. ferox
- Himalayan Honeysuckle - Leycesteria Formosa Wall.
- Himalayan Mayapple - Podophyllum Hexandrum Royle
- Himalayan Musk Rose - Rosa Brunonii Lindl.
- Himantostemma Pringlei A. Gray
- Himber - Rajania Cordata L.
- Hinahina - Geranium Cuneatum Hook.
- Hinahina - Geranium Cuneatum Hook. var. cuneatum
- Hinahina - Geranium Cuneatum Hook. var. hololeucum A. Gray
- Hinahina - Geranium Cuneatum Hook. var. hypoleucum A. Gray
- Hinahina - Geranium Cuneatum Hook. var. tridens (Hillebr.) Fosberg
- Hinahina Kahakai - Nama Sandwicense A. Gray
- Hinchahuevos - Sapium Laurifolium (A. Rich.) Griseb.
- Hinckley Oak - Quercus Hinckleyi C.H. Mull.
- Hinckley's Brickellbush - Brickellia Hinckleyi Standl.
- Hinckley's Brickellbush - Brickellia Hinckleyi Standl. var. hinckleyi
- Hinckley's Golden Columbine - Aquilegia Chrysantha A. Gray var. hinckleyana (Munz) Lott
- Hinckley's Polemonium - Polemonium Pauciflorum S. Watson ssp. hinckleyi (Standl.) Wherry
- Hinckley's Spreadwing - Eurytaenia Hinckleyi Mathias & Constance
- Hinds' Nightshade - Solanum Hindsianum Benth.
- Hinoki False Cypress - Chamaecyparis Obtusa (Siebold & Zucc.) Siebold & Zucc. ex Endl.
- Hippeastrum Equestre (Aiton) Herb.
- Hippeastrum - Hippeastrum Herb.
- Hippeastrum Reginae (L.) Herb. [excluded]
- Hippeastrum Vittatum (L'Hér.) Herb. [excluded]
- Hippo Grass - Echinochloa Stagnina (Retz.) P. Beauv.
- Hippo Grass - Vossia Cuspidata Griff.
- Hippo Grass - Vossia Wall. & Griffith
- Hippobroma - Hippobroma G. Don
- Hippochaete Hyemalis (L.) Bruhin
- Hippochaete Hyemalis (L.) Bruhin ssp. affinis (Engelm.) W.A. Weber
- Hippochaete Laevigata (A. Braun) Farw.
- Hippochaete Variegata (Schleich. ex F. Weber & D. Mohr) Bruhin
- Hippocratea Caribaea Urb.
- Hippocratea - Hippocratea L.
- Hippocrepis Bicontorta Loisel.
- Hippocrepis Bourgaei Nyman
- Hippocrepis Emerus (L.) Lassen
- Hippocrepis Emerus (L.) Lassen ssp. emeroides (Boiss. & Spruner) Greuter & Burdet e
- Hippocrepis Glauca Ten.
- Hippocrepis - Hippocrepis Commutata Pau
- Hippocrepis - Hippocrepis L.
- Hippocrepis Multisiliquosa L.
- Hippocrepis Salzmannii Boiss. & Reut.
- Hippocrepis Scabra DC.
- Hippocrepis Unisiliquosa L.
- Hippomane - Hippomane L.
- Hipposelinum Levisticum (L.) Britton & Rose
- Hippuris Lanceolata Retz.
- Hiptage - Hiptage Benghalensis (L.) Kurz
- Hiptage - Hiptage Gaertn., nom. cons.
- Hiraea Faginea (Sw.) Nied. [excluded]
- Hiraea Jacq.
- Hirculus Platysepalus (Trautv.) W.A. Weber
- Hirculus Platysepalus (Trautv.) W.A. Weber ssp. crandallii (Gandog.) W.A. Weber
- Hirculus Prorepens (Fisch. ex Sternb.) Á. Löve & D. Löve
- Hirculus Serpyllifolius (Pursh) W.A. Weber
- Hirculus Serpyllifolius (Pursh) W.A. Weber ssp. chrysanthus (A. Gray) W.A. Weber
- Hirschfeldia - Hirschfeldia Moench
- Hirst's Panicgrass - Dichanthelium Hirstii (Swallen) Kartesz
- Hirsute Artocarpus - Artocarpus Hirsutus Lam.
- Hirsute Raspberry - Rubus Hirsutus Thunb.
- Hirsute Sedge - Carex Complanata Torr. & Hook.
- Hirtella Americana Jacq., non L.
- Hirtella - Hirtella L.
- Hirtella Jamaicensis Urb.
- Hirtella Multiflora Urb.
- Hirtella Portoricensis Humb. & Bonpl.
- Hispanic Crambe - Crambe Hispanica L.
- Hispanic Hyacinthoides - Hyacinthoides Hispanica (Mill.) Rothm.
- Hispaniolan Spleenwort - Asplenium Sessilifolium Desv.
- Hispaniolan Tree Destroyer - Dendrophthora Serpyllifolia (Griseb.) Krug & Urb.
- Hispid Agrestia Lichen - Agrestia Hispida (Mereschk.) Hale & W.L. Culb.
- Hispid Bird's-beak - Cordylanthus Mollis A. Gray ssp. hispidus (Pennell) T.I. Chuang & Heckard
- Hispid Campylium Moss - Campylium Hispidulum (Brid.) Mitt.
- Hispid False Mallow - Malvastrum Hispidum (Pursh) Hochr.
- Hispid Mock Vervain - Glandularia Hispida Ruiz & Pav.
- Hispid Needle Lichen - Chaenotheca Hispidula (Ach.) Zahlbr.
- Hispid Phyllostegia - Phyllostegia Hispida Hillebr.
- Hispid Rose - Rosa Blanda Aiton var. hispida Farw.
- Hispid Starbur - Acanthospermum Hispidum DC.
- Hispid Strophanthus - Strophanthus Hispidus A. DC.
- Hispid Wreath Lichen - Phaeophyscia Hispidula (Ach.) Essl.
- Hispid Yellowcress - Rorippa Palustris (L.) Besser ssp. hispida (Desv.) Jonsell
- Histiopteris - Histiopteris (j. Agardh) J. Sm.
- Hitchcock's Bladderpod - Lesquerella Hitchcockii Munz
- Hitchcock's Blue-eyed Grass - Sisyrinchium Hitchcockii Douglass M. Hend.
- Hitchcock's Mock Orange - Philadelphus Hitchcockianus Hu
- Hitchcock's Sedge - Carex Hitchcockiana Dewey
- Hitchcock's Smooth Woodrush - Luzula Glabrata (Hoppe ex Rostk.) Desv. var. hitchcockii (Hämet-Ahti) Dorn
- Hitchenia - Hitchenia Wall.
- Hjaltalinia Villosa (L.) Á. Löve & D. Löve
- Ho'awa - Pittosporum Confertiflorum A. Gray
- Hoary Alyssum - Berteroa Incana (L.) DC.
- Hoary Bahia - Bahia Absinthifolia Benth. var. dealbata (A. Gray) A. Gray
- Hoary Balsamroot - Balsamorhiza Incana Nutt.
- Hoary Basil - Ocimum Canum Sims
- Hoary Basil - Ocimum Kilimandscharicum Guerke
- Hoary Blackfoot - Melampodium Cinereum DC.
- Hoary Blackfoot - Melampodium Cinereum DC. var. cinereum
- Hoary Blackfoot - Melampodium Cinereum DC. var. hirtellum Stuessy
- Hoary Blackfoot - Melampodium Cinereum DC. var. ramosissimum (DC.) A. Gray
- Hoary Bowlesia - Bowlesia Incana Ruiz & Pav.
- Hoary Brome - Bromus Subvelutinus Shear
- Hoary Buckwheat - Eriogonum Saxatile S. Watson
- Hoary Caper - Capparis Incana Kunth
- Hoary False Goldenaster - Heterotheca Canescens (DC.) Shinners
- Hoary Fleabane - Erigeron Canus A. Gray
- Hoary Frostweed - Helianthemum Bicknellii Fernald
- Hoary Groundsel - Packera Werneriifolia (A. Gray) W.A. Weber & Á. Löve
- Hoary Hawthorn - Crataegus Lanata Beadle
- Hoary Manzanita - Arctostaphylos Canescens Eastw.
- Hoary Manzanita - Arctostaphylos Canescens Eastw. ssp. canescens
- Hoary Milkpea - Galactia Canescens Benth.
- Hoary Mock Orange - Philadelphus Pubescens Loisel.
- Hoary Mock Orange - Philadelphus Pubescens Loisel. var. intectus (Beadle) A.H. Moore
- Hoary Mock Orange - Philadelphus Pubescens Loisel. var. pubescens
- Hoary Mountainmint - Pycnanthemum Incanum (L.) Michx.
- Hoary Mountainmint - Pycnanthemum Incanum (L.) Michx. var. incanum
- Hoary Mountainmint - Pycnanthemum Incanum (L.) Michx. var. puberulum (E. Grant & Epling) Fernald
- Hoary Pea - Lathyrus Polymorphus Nutt. ssp. incanus (J.G. Sm. & Rydb.) C.L. Hitchc.
- Hoary Phacelia - Phacelia Incana Brand
- Hoary Pincushionplant - Navarretia Eriocephala H. Mason
- Hoary Plantain - Plantago Media L.
- Hoary Puccoon - Lithospermum Canescens (Michx.) Lehm.
- Hoary Ragwort - Senecio Erucifolius L.
- Hoary Sandmat - Chamaesyce Lata (Engelm.) Small
- Hoary Skullcap - Scutellaria Incana Biehler
- Hoary Skullcap - Scutellaria Incana Biehler var. australis (Epling) Collins, ined.
- Hoary Skullcap - Scutellaria Incana Biehler var. incana
- Hoary Skullcap - Scutellaria Incana Biehler var. punctata (Chapm.) C. Mohr
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. canescens
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. canescens var. ambigua B.L. Turner
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. canescens var. canescens
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. canescens var. incana (Lindl.) A. Gray
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. canescens var. sessiliflora (Nutt.) B.L. Tu
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. glabra (A. Gray) B.L. Turner
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. glabra (A. Gray) B.L. Turner var. aristata
- Hoary Tansyaster - Machaeranthera Canescens (Pursh) A. Gray ssp. glabra (A. Gray) B.L. Turner var. glabra A.
- Hoary Ticktrefoil - Desmodium Canescens (L.) DC.
- Hoary Townsend Daisy - Townsendia Incana Nutt.
- Hoary Verbena - Verbena Stricta Vent.
- Hoary Yellowcress - Rorippa Barbareifolia (DC.) Kitagawa
- Hoaryleaf Ceanothus - Ceanothus Crassifolius Torr.
- Hoarypea - Tephrosia Pers.
- Hoarypea - Tephrosia Sinapou (Buc'hoz) A. Chev.
- Hoarypea - Tephrosia ×floridana (Vail) Isely
- Hobblebush - Viburnum Lantanoides Michx.
- Hobdy's Naupaka - Scaevola Hobdyi W.L. Wagner
- Hobdy's Spleenwort - Asplenium Hobdyi W.H. Wagner
- Hobdy's Woodfern - Dryopteris Hobdyana W.H. Wagner
- Hobsonia Lichen - Hobsonia Massee
- Hochstetter's Map Lichen - Rhizocarpon Hochstetteri (Körb.) Vain.
- Hodgsonia - Hodgsonia Hook. f. & Thomson
- Hoe Nightshade - Solanum Physalifolium Rusby
- Hoffman's Gilia - Gilia Tenuiflora Benth. ssp. hoffmannii (Eastw.) A.D. Grant & V.E. Grant
- Hoffmania Lanceolata Griseb., database artifact
- Hoffmann's Blacksnakeroot - Sanicula Hoffmannii (Munz) Shan & Constance (pro hybr.)
- Hoffmann's Buckwheat - Eriogonum Hoffmannii S. Stokes
- Hoffmann's Buckwheat - Eriogonum Hoffmannii S. Stokes var. hoffmannii
- Hoffmann's Cryptantha - Cryptantha Hoffmannii I.M. Johnst.
- Hoffmann's Nightshade - Solanum Xanti A. Gray var. hoffmannii Munz
- Hoffmann's Rockcress - Arabis Hoffmannii (Munz) Rollins
- Hoffmann's Teddybear Cholla - Cylindropuntia ×fosbergii (C.B. Wolf) Backeb.
- Hoffmannia Lanceolata Griseb.
- Hoffmannsegg's Wild Coffee - Psychotria Hoffmannseggiana (Roem. & Schult.) Müll. Arg.
- Hoffmannsegg's Wild Coffee - Psychotria Hoffmannseggiana (Roem. & Schult.) Müll. Arg. var. tribracteata (Sw.) Steyerm.
- Hoffmannseggia Brachycarpa A. Gray
- Hoffmannseggia Caudata A. Gray
- Hoffmannseggia Densiflora Benth.
- Hoffmannseggia Densiflora Benth. var. capitata Fisher
- Hoffmannseggia Densiflora Benth. var. demissa (A. Gray) Fisher
- Hoffmannseggia Densiflora Benth. var. pringlei Fisher
- Hoffmannseggia Densiflora Benth. var. stricta (Benth.) Fisher
- Hoffmannseggia Falcaria Cav.
- Hoffmannseggia Jamesii Torr. & A. Gray
- Hoffmannseggia Melanosticta (Schauer) A. Gray
- Hoffmannseggia Parryi (Fisher) B.L. Turner
- Hofmeisteria Laphamioides Rose
- Hofmeisteria Pluriseta A. Gray
- Hog Plum - Prunus Umbellata Elliott
- Hog Plum - Prunus Umbellata Elliott var. injuncunda (Small) Sarg.
- Hog Plum - Prunus Umbellata Elliott var. umbellata
- Hog's-fennel - Peucedanum Officinale L.
- Hogfennel - Peucedanum Palustre (L.) Moench
- Hogpeanut - Amphicarpaea Elliott ex Nutt.
- Hogvine - Merremia Umbellata (L.) Hallier f.
- Hogwood - Sagraea Dc.
- Hogwort - Croton Capitatus Michx.
- Hogwort - Croton Capitatus Michx. var. capitatus
- Hoita Hallii Rydb.
- Hoita Longiloba Rydb.
- Hoita Rhombifolia (Torr.) Rydb.
- Hoita Villosa Greene
- Hoja Menuda - Siphoneugena Densiflora Berg
- Holacantha Emoryi A. Gray
- Holacantha - Holacantha A. Gray
- Holarrhena Febrifuga Klotzsch
- Holarrhena - Holarrhena Pubescens (Buch.-Ham.) Wall. ex G. Don
- Holarrhena - Holarrhena R. Br.
- Holarrhena Wulfsbergii Stapf
- Holboell's Rockcress - Arabis Holboellii Hornem.
- Holboell's Rockcress - Arabis Holboellii Hornem. var. holboellii
- Holboell's Rockcress - Arabis Holboellii Hornem. var. pinetorum (Tidestr.) Rollins
- Holcophacos Distortus (Torr. & A. Gray) Rydb.
- Holcus Bicolor L.
- Holcus Halepensis L.
- Holcus Odoratus L.
- Holcus Pertusus L.
- Holcus Sorghum L.
- Holcus Striatus L.
- Holdback - Pomaria Cav.
- Holdtight - Medinilla Venosa (Blume) Blume
- Hole-in-the-sand Plant - Nicolletia A. Gray
- Holei - Ochrosia Compta K. Schum.
- Holio - Cryptocarya Mannii Hillebr.
- Hollisteria - Hollisteria S. Watson
- Hollowheart - Acnistus Arborescens (L.) Schltdl.
- Hollowleaf Annual Lupine - Lupinus Succulentus Douglas ex K. Koch
- Hollowstem Burnet Saxifrage - Pimpinella Major (L.) Huds.
- Holly - Ilex L.
- Holly - Ilex Sandwicensis (Endl.) Loes.
- Holly - Ilex Volkensiana (Loes.) Kanehira & Hatusima
- Holly Oak - Quercus Ilex L.
- Holly Osmanthus - Osmanthus Heterophyllus (G. Don) P.S. Green
- Hollyberry Cotoneaster - Cotoneaster Bullatus Boiss.
- Hollyberry Cotoneaster - Cotoneaster Bullatus Boiss. var. macrophyllus Boiss.
- Hollybush - Tetracoccus Ilicifolius Coville & Gilman
- Hollyfern - Arachniodes Blume
- Hollyfern - Polystichum Roth
- Hollyfern - Polystichum ×hagenahii Cody
- Hollyfern - Polystichum ×potteri Barrington
- Hollyhock - Alcea L.
- Hollyhock - Alcea Pallida (Waldst. & Kit. ex Willd.) Waldst. & Kit.
- Hollyhock - Alcea Rosea L.
- Hollyleaf Buckthorn - Rhamnus Crocea Nutt. ssp. pilosa (Trel.) C.B. Wolf
- Hollyleaf Bur Ragweed - Ambrosia Ilicifolia (A. Gray) Payne
- Hollyleaf Ceanothus - Ceanothus Purpureus Jeps.
- Hollyleaf Cherry - Prunus Ilicifolia (Nutt. ex Hook. & Arn.) D. Dietr.
- Hollyleaf Cherry - Prunus Ilicifolia (Nutt. ex Hook. & Arn.) D. Dietr. ssp. ilicifolia
- Hollyleaf Cherry - Prunus Ilicifolia (Nutt. ex Hook. & Arn.) D. Dietr. ssp. lyonii (Eastw.) P.H. Rave
- Hollyleaf Clover - Trifolium Gymnocarpon Nutt.
- Hollyleaf Clover - Trifolium Gymnocarpon Nutt. ssp. gymnocarpon
- Hollyleaf Fringedfern - Lomariopsis Kunzeana (C. Presl ex Underw.) Holttum
- Hollyleaf Gilia - Gilia Latiflora (A. Gray) A. Gray
- Hollyleaf Gilia - Gilia Latiflora (A. Gray) A. Gray ssp. cuyamensis A.D. Grant & V.E. Grant
- Hollyleaf Gilia - Gilia Latiflora (A. Gray) A. Gray ssp. davyi (Milliken) A.D. Grant & V.E. Grant
- Hollyleaf Gilia - Gilia Latiflora (A. Gray) A. Gray ssp. elongata A.D. Grant & V.E. Grant
- Hollyleaf Gilia - Gilia Latiflora (A. Gray) A. Gray ssp. latiflora
- Hollyleaf Pincushionplant - Navarretia Atractyloides (Benth.) Hook. & Arn.
- Hollyleaf Redberry - Rhamnus Ilicifolia Kellogg
- Hollyleaved Barberry - Mahonia Aquifolium (Pursh) Nutt.
- Holm Sedge - Carex Heteroneura W. Boott var. chalciolepis (T. Holm) F.J. Herm.
- Holm's Ragwort - Senecio Amplectens A. Gray var. holmii (Greene) Harrington
- Holm's Reedgrass - Calamagrostis Holmii Lange
- Holmes' Hawthorn - Crataegus Holmesiana Ashe
- Holmgren's Lupine - Lupinus Holmgrenianus C.P. Sm.
- Holmgrenia Acuminata (Bryhn) Grout
- Holmgrenia Andina (Nutt.) W.L. Wagner & Hoch
- Holmgrenia Chrysea (Schwägr.) Lindb.
- Holmgrenia Diminutiva Grout
- Holmgrenia Intricata (Hartm.) Lindb.
- Holmgrenia Rufescens (Brid.) Lindb.
- Holmgrenia Stricta (Lor.) Grout
- Holmskioldia - Holmskioldia Retz.
- Holo Lupine - Lupinus Holosericeus Nutt.
- Holodiscus Boursieri (Carrière) Rehder
- Holodiscus Discolor (Pursh) Maxim. ssp. franciscanus (Rydb.) Roy L. Taylor & MacBryd
- Holodiscus Discolor (Pursh) Maxim. var. ariaefolius (Sm.) Asch. & Graebn.
- Holodiscus Discolor (Pursh) Maxim. var. delnortensis Ley
- Holodiscus Discolor (Pursh) Maxim. var. dumosus (Nutt. ex Hook.) Maxim. ex J.M. Coul
- Holodiscus Discolor (Pursh) Maxim. var. franciscanus (Rydb.) Jeps.
- Holodiscus Discolor (Pursh) Maxim. var. glabrescens (Greenm.) Jeps.
- Holodiscus Dumosus (Nutt. ex Hook.) A. Heller ssp. saxicola (A. Heller) Abrams
- Holodiscus Dumosus (Nutt. ex Hook.) A. Heller var. australis (A. Heller) Ley
- Holodiscus Dumosus (Nutt. ex Hook.) A. Heller var. glabrescens (Greenm.) C.L. Hichc
- Holodiscus Dumosus (Nutt. ex Hook.) A. Heller var. typicus Ley
- Holodiscus Glabrescens (Greenm.) A. Heller
- Holodiscus Microphyllus Rydb.
- Holodiscus Microphyllus Rydb. var. glabrescens (Greenm.) Ley
- Holodiscus Microphyllus Rydb. var. microphyllus
- Holodiscus Microphyllus Rydb. var. sericeus Ley
- Holodiscus Microphyllus Rydb. var. typicus Ley
- Holographis Nees
- Holographis Virgata (Harv. ex Benth. & Hook. f.) Daniel [excluded]
- Holoschoenus Romanus (L.) Fritsch
- Holoschoenus Vulgaris Link
- Holosteum - Holosteum L.
- Holosteum Umbellatum L. ssp. umbellatum
- Holozonia - Holozonia Greene
- Holy Basil - Ocimum Tenuiflorum L.
- Holy Dandelion - Glyptopleura Setulosa A. Gray
- Holy Ghost Ipomopsis - Ipomopsis Sancti-spiritus Wilken & Fletcher
- Holywood - Guaiacum Sanctum L.
- Holzinger's Brachythecium Moss - Brachythecium Holzingeri (Grout) Grout
- Holzinger's Eupatorium - Eutrochium Purpureum (L.) E.E. Lamont var. holzingeri (Rydb.) E.E. Lamont
- Holzinger's Orthotrichum Moss - Orthotrichum Holzingeri Renauld & Cardot
- Holzinger's Venus' Looking-glass - Triodanis Holzingeri McVaugh
- Homalia Gracilis James
- Homalia Jamesii Schimp.
- Homalia Jamesii Schimp. var. gracilis (James) Wagn.
- Homalia Moss - Homalia (brid.) Schimp.
- Homalia Moss - Homalia Trichomanoides (Hedw.) Schimp.
- Homalia Sharpii R.S. Williams
- Homaliadelphus Moss - Homaliadelphus Dix. & P. Varde
- Homalium - Homalium Jacq.
- Homalium Leiogynum S.F. Blake
- Homalium Pleiandrum S.F. Blake
- Homalobus Caespitosus Nutt.
- Homalobus Campestris Nutt.
- Homalobus Tenellus (Pursh) Britton
- Homalobus Vexilliflexus (Sheldon) Rydb.
- Homalocenchrus Hexandrus (Sw.) Kuntze
- Homalocenchrus Lenticularis (Michx.) Kuntze
- Homalocenchrus Monandrus (Sw.) Kuntze
- Homalocenchrus Oryzoides (L.) Pollich
- Homalocenchrus Virginicus (Willd.) Britton
- Homalocephala Texensis (Hopffer) Britton & Rose
- Homalocladium - Homalocladium (f. Muell.) L.H. Bailey
- Homalomena Rubescens (Roxb.) Kunth
- Homalomena Schott
- Homalotheciella Fabronifolia (Grout) Broth.
- Homalotheciella Moss - Homalotheciella (cardot) Broth.
- Homalotheciella Moss - Homalotheciella Subcapillata (Hedw.) Broth.
- Homalothecium Bonplandii A. Jaeger, nom. illeg.
- Homalothecium Leskeoides (Hook.) H. Rob.
- Homalothecium Megaptilum (Sull.) H. Rob.
- Homalothecium Moss - Homalothecium Schimp.
- Homalothecium Nevadense (Lesq.) Renauld & Cardot var. subulatum Renauld & Cardot
- Homalothecium Nitens (Hedw.) H. Rob.
- Homalothecium Nuttallii (Wilson) A. Jaeger var. hamatidens (Kindb.) Grout
- Homalothecium Nuttallii (Wilson) A. Jaeger var. stoloniferum (Lesq.) L.F. Koch
- Homalothecium Nuttallii (Wilson) A. Jaeger var. tenue (Kindb.) Grout
- Homeria Collina (Thunb.) Salisb.
- Homeria Flaccida Sweet
- Homeria Ochroleuca Salisb.
- Homeria Pallida Baker
- Homeria Vent.
- Homomallium Adnatum (Hedw.) Broth. var. nelsonii Kindb. ex Gier
- Homomallium Moss - Homomallium (schimp.) Loeske
- Homomallium Moss - Homomallium Adnatum (Hedw.) Broth.
- Homomallium Moss - Homomallium Incurvatum (Brid.) Loeske
- Homopholis C.e. Hubb.
- Homopholis Proluta (F. Muell.) R.D. Webster
- Homostegia Fuckel
- Homostegia Piggotii (Berk. & Broome) P. Karst.
- Honckenya Diffusa (Hornem.) Á. Löve & D. Löve
- Honckenya - Honckenya Ehrh.
- Honckenya Oblongifolia Torr. & A. Gray
- Honckenya Peploides (L.) Ehrh. var. major (Hook.) Abrams
- Honckenya Peploides (L.) Ehrh. var. robusta (Fernald) House
- Honduras Mahogany - Swietenia Macrophylla King
- Honewort - Cryptotaenia Dc.
- Honey Bluestem - Schizachyrium Spadiceum (Swallen) Wipff
- Honey Mesquite - Prosopis Glandulosa Torr.
- Honey Mesquite - Prosopis Glandulosa Torr. var. glandulosa
- Honey Mesquite - Prosopis Glandulosa Torr. var. prostrata Burkart
- Honey-flower - Melianthus Major L.
- Honeycombed Lichen - Menegazzia A. Massal.
- Honeycombed Lichen - Menegazzia Terebrata (Hoffm.) A. Massal.
- Honeycombhead - Balduina Nutt.
- Honeycup - Zenobia D. Don
- Honeycup - Zenobia Pulverulenta (W. Bartram ex Willd.) Pollard
- Honeyherb - Phyla Dulcus (Trevir.) Moldenke
- Honeylocust - Gleditsia Triacanthos L.
- Honeyscented Pincushionplant - Navarretia Mellita Greene
- Honeysuckle - Lonicera Chrysantha Turcz. ex Ledeb.
- Honeysuckle - Lonicera L.
- Honeysuckle - Lonicera ×heckrottii Rehder
- Honeysuckle - Lonicera ×minutiflora Zabel
- Honeysuckle - Lonicera ×notha Zabel
- Honeysuckle - Lonicera ×salicifolia Dieck ex Zabel
- Honeysweet - Tidestromia Standl.
- Honeyvine - Cynanchum Laeve (Michx.) Pers.
- Honeyweed - Leonurus Sibiricus L.
- Honeywort - Cerinthe L.
- Honeywort - Cerinthe Major L.
- Hong Kong Kumquat - Fortunella Hindsii (Champ. ex Benth.) Swingle
- Honohono - Haplostachys Haplostachya (A. Gray) H. St. John
- Honokahua Melicope - Melicope Orbicularis (Hillebr.) T.G. Hartley & B.C. Stone
- Honolulu Cyanea - Cyanea Acuminata (Gaudich.) Hillebr.
- Honolulu Lacefern - Ctenitis Honolulensis (Hook.) Copeland
- Honolulu Melicope - Melicope Hosakae (H. St. John) W.L. Wagner & R.K. Shannon
- Hood Canarygrass - Phalaris Paradoxa L.
- Hood River Milkvetch - Astragalus Hoodianus Howell
- Hood's Sedge - Carex Hoodii Boott
- Hooded Arrowhead - Sagittaria Calycina Engelm.
- Hooded Arrowhead - Sagittaria Calycina Engelm. var. calycina
- Hooded Arrowhead - Sagittaria Calycina Engelm. var. spongiosa Engelm.
- Hooded Coralroot - Corallorhiza Striata Lindl.
- Hooded Coralroot - Corallorhiza Striata Lindl. var. striata
- Hooded Lady's Tresses - Spiranthes Romanzoffiana Cham.
- Hooded Orchid - Galeandra Bicarinata G.A. Romero & P.M. Brown
- Hooded Orchid - Galeandra Lindl. & F.A. Bayer
- Hooded Pitcherplant - Sarracenia Minor Walter
- Hooded Windmill Grass - Chloris Cucullata Bisch.
- Hook-leaf Mallee - Eucalyptus Uncinata Turcz.
- Hooked Bristlegrass - Setaria Verticillata (L.) P. Beauv.
- Hooked Pincushionplant - Navarretia Hamata Greene
- Hooked Pincushionplant - Navarretia Hamata Greene ssp. hamata
- Hooked Pincushionplant - Navarretia Hamata Greene ssp. leptantha (Greene) H. Mason
- Hookedspur Violet - Viola Adunca Sm.
- Hookedspur Violet - Viola Adunca Sm. var. adunca
- Hookedspur Violet - Viola Adunca Sm. var. oxyceras (S. Watson) S. Watson ex Jeps.
- Hooker Bugseed - Corispermum Hookeri Mosyakin
- Hooker Bugseed - Corispermum Hookeri Mosyakin var. hookeri
- Hooker Bugseed - Corispermum Hookeri Mosyakin var. pseudodeclinatum Mosyakin
- Hooker's Balsamroot - Balsamorhiza Hookeri (Hook.) Nutt.
- Hooker's Balsamroot - Balsamorhiza Hookeri (Hook.) Nutt. var. hookeri
- Hooker's Bristle Fern - Trichomanes Hookeri C. Presl
- Hooker's Buckwheat - Eriogonum Hookeri S. Watson
- Hooker's Ceanothus - Ceanothus Velutinus Douglas ex Hook. var. hookeri M.C. Johnst.
- Hooker's Cinquefoil - Potentilla Hookeriana Lehm.
- Hooker's Cinquefoil - Potentilla Hookeriana Lehm. ssp. chamissonis (Hultén) Hultén
- Hooker's Cinquefoil - Potentilla Hookeriana Lehm. ssp. hookeriana
- Hooker's Desert Sandwort - Arenaria Hookeri Nutt. ssp. desertorum (Maguire) W.A. Weber
- Hooker's Dwarf Polypody - Grammitis Hookeri (Brack.) Copeland
- Hooker's Eryngo - Eryngium Hookeri Walp.
- Hooker's Evening Primrose - Oenothera Elata Kunth
- Hooker's Evening Primrose - Oenothera Elata Kunth ssp. hirsutissima (A. Gray ex S. Watson) W. Dietr.
- Hooker's Evening Primrose - Oenothera Elata Kunth ssp. hookeri (Torr. & A. Gray) W. Dietr. & W.L. Wagner
- Hooker's Inula - Inula Hookeri C.B. Clarke
- Hooker's Manzanita - Arctostaphylos Hookeri G. Don
- Hooker's Manzanita - Arctostaphylos Hookeri G. Don ssp. hookeri
- Hooker's Matted Lichen - Pannaria Hookeri (Borrer ex Sm.) Nyl.
- Hooker's Milkwort - Polygala Hookeri Torr. & A. Gray
- Hooker's Mountain-avens - Dryas Octopetala L. ssp. hookeriana (Juz.) Hultén
- Hooker's Orchid - Platanthera Hookeri (Torr. ex A. Gray) Lindl.
- Hooker's Physcomitrium Moss - Physcomitrium Hookeri Hampe
- Hooker's Sandwort - Arenaria Hookeri Nutt.
- Hooker's Sandwort - Arenaria Hookeri Nutt. ssp. hookeri
- Hooker's Sandwort - Arenaria Hookeri Nutt. ssp. pinetorum (A. Nelson) W.A. Weber
- Hooker's Scratchdaisy - Croptilon Hookerianum (Torr. & A. Gray) House
- Hooker's Scratchdaisy - Croptilon Hookerianum (Torr. & A. Gray) House var. graniticum (E.B. Sm.) E.B. Sm.
- Hooker's Scratchdaisy - Croptilon Hookerianum (Torr. & A. Gray) House var. hookerianum
- Hooker's Scratchdaisy - Croptilon Hookerianum (Torr. & A. Gray) House var. validum (Rydb.) E.B. Sm.
- Hooker's Sedge - Carex Hookeriana Dewey
- Hooker's Silene - Silene Hookeri Nutt.
- Hooker's Silene - Silene Hookeri Nutt. ssp. hookeri
- Hooker's Silene - Silene Hookeri Nutt. ssp. pulverulenta (M. Peck) C.L. Hitchc. & Maguire
- Hooker's St. Johnswort - Hypericum Hookerianum Wight & Arn.
- Hooker's Townsend Daisy - Townsendia Hookeri Beaman
- Hooker's Wildparsley - Musineon Divaricatum (Pursh) Raf. var. hookeri (Torr. & A. Gray) Mathias
- Hookera Filifolia (S. Watson) Greene
- Hookera Leptandra Greene
- Hookera Minor (Benth.) Kunze
- Hookera Orcuttii Greene
- Hookera Pulchella Salisb.
- Hookera Rosea Greene
- Hookera Stellaris (S. Watson) Greene
- Hookeria Moss - Hookeria Lucens (Hedw.) Sm.
- Hookeria Moss - Hookeria Sm.
- Hookeria Pallida Hornsch.
- Hookeriopsis Heteroica Cardot
- Hooky Grass - Ancistrachne Uncinulata (R. Br.) S.T. Blake
- Hoopvine - Trichostigma Octandrum (L.) H. Walt.
- Hoosier Pass Ipomopsis - Ipomopsis Globularis (Brand) W.A. Weber
- Hoover's Bentgrass - Agrostis Hooveri Swallen
- Hoover's Biscuitroot - Lomatium Hooveri (Mathias & Constance) Constance & Ertter
- Hoover's Brodiaea - Brodiaea Elegans Hoover ssp. hooveri Niehaus
- Hoover's Calicoflower - Downingia Bella Hoover
- Hoover's Cryptantha - Cryptantha Hooveri I.M. Johnst.
- Hoover's Desertparsley - Lomatium Tuberosum Hoover
- Hoover's Deserttrumpet - Eriogonum Trichopes Torr. var. hooveri Reveal
- Hoover's Eryngo - Eryngium Aristulatum Jeps. var. hooveri Sheikh
- Hoover's Manzanita - Arctostaphylos Hooveri P.V. Wells
- Hoover's Sandmat - Chamaesyce Hooveri (L.C. Wheeler) Koutnik
- Hoover's Umbrellawort - Tauschia Hooveri Mathias & Constance
- Hoover's Western Rosinweed - Calycadenia Hooveri G.D. Carr
- Hoover's Woollystar - Eriastrum Hooveri (Jeps.) H. Mason
- Hop - Humulus L.
- Hop Sedge - Carex Lupulina Muhl. ex Willd.
- Hopea - Hopea Micrantha Hook. f.
- Hopea - Hopea Roxb.
- Hophead Philippine Violet - Barleria Lupulina Lindl.
- Hophornbeam - Ostrya Scop.
- Hophornbeam - Ostrya Virginiana (Mill.) K. Koch
- Hopi Milkvetch - Astragalus Fucatus Barneby
- Hopi Tea Greenthread - Thelesperma Megapotamicum (Spreng.) Kuntze
- Hopia Obtusa (Kunth) Zuloaga & Morrone
- Hopp's Figwort - Scrophularia Canina L. ssp. hoppii (Koch) Fourn.
- Hoppner's Sedge - Carex Subspathacea Wormsk. ex Hornem.
- Hopsage - Grayia Hook. & Arn.
- Hoptree - Ptelea L.
- Hopue - Urera Glabra (Hook. & Arn.) Weddell
- Hordelymus (jess.) Harz
- Hordeum Aegiceras Nees ex Royle
- Hordeum Bogdanii Wilensky
- Hordeum Boreale Scribn. & J.G. Sm.
- Hordeum Brevisubulatum (Trin.) Link
- Hordeum Caespitosum Scribn. ex Pammel
- Hordeum Californicum Covas & Stebbins
- Hordeum Comosum J. Presl
- Hordeum Distichon L.
- Hordeum Euclaston Steud.
- Hordeum Geniculatum All.
- Hordeum Glaucum Steud.
- Hordeum Gussoneanum Parl.
- Hordeum Hexastichon L.
- Hordeum Hexastichum L., orth. var.
- Hordeum Hystrix Roth
- Hordeum Irregulare Aberg & Wiebe
- Hordeum Jubatum L. ssp. breviaristatum Bowden
- Hordeum Jubatum L. var. boreale (Scribn. & J.G. Sm.) B. Boivin
- Hordeum Jubatum L. var. caespitosum (Scribn. ex Pammel) Hitchc.
- Hordeum Leporinum Link
- Hordeum Montanense Scribn.
- Hordeum Nodosum L. p.p.
- Hordeum Nodosum L. var. boreale (Scribn. & J.G. Sm.) Hitchc.
- Hordeum Pammelii Scribn. & C.R. Ball
- Hordeum Parodii Covas
- Hordeum Pusillum Nutt. ssp. euclaston (Steud.) Hauman [excluded]
- Hordeum Pusillum Nutt. var. pubens Hitchc.
- Hordeum Sativum Pers.
- Hordeum Secalinum Schreb. [excluded]
- Hordeum Spontanum K. Koch, database artifact
- Hordeum Stebbinsii Covas
- Hordeum Vulgare L. ssp. hexastichon (L.) Bonnier & Layens
- Hordeum Vulgare L. var. trifurcatum (Schltdl.) Alef.
- Horehound - Ballota L.
- Horehound - Marrubium Incanum Desr. [excluded]
- Horehound - Marrubium L.
- Horehound - Marrubium Peregrinum L.
- Horehound - Marrubium Vulgare L.
- Horehound-leaf Nettle - Urtica Ballotifolia Weddell
- Horizontal Felt Lichen - Peltigera Horizontalis (Huds.) Baumg.
- Horizontal Woody Rockcress - Arabis Suffrutescens S. Watson var. horizontalis (Greene) Rollins
- Horkelia Baileyi (S. Watson) Rydb.
- Horkelia Beneolens A. Nelson & J.F. Macbr.
- Horkelia Bolanderi A. Gray ssp. clevelandii (Greene) D.D. Keck
- Horkelia Bolanderi A. Gray ssp. parryi (S. Watson) D.D. Keck
- Horkelia Capitata Lindl.
- Horkelia Elata (Greene) Rydb.
- Horkelia Frondosa (Greene) Rydb.
- Horkelia Fusca Lindl. var. capitata (Lindl.) Wawra
- Horkelia Fusca Lindl. var. parviflora (Nutt. ex Torr. & A. Gray) Wawra
- Horkelia Fusca Lindl. var. pseudocapitata (Rydb. ex Howell) Wawra
- Horkelia Glandulosa Eastw.
- Horkelia Gordonii Hook.
- Horkelia - Horkelia Cham. & Schltdl.
- Horkelia Purpurascens S. Watson
- Horkelia Purpurascens S. Watson ssp. congdonis (Rydb.) Abrams
- Hormidium Pygmaeum (Hook.) Benth. & Hook. f.
- Hormidium Tripterum (Brongn.) Cogn.
- Horn Calcareous Moss - Mnium Hornum Hedw.
- Horn Loco Milkvetch - Astragalus Missouriensis Nutt. var. mimetes Barneby
- Horn Nut - Trapa Bicornis Osbeck
- Horn's Milkvetch - Astragalus Hornii A. Gray
- Horn-leaved Takakia - Takakia Ceratophylla (Mitten) Grolle
- Hornbeam - Carpinus L.
- Horned Bladderwort - Utricularia Cornuta Michx.
- Horned Pondweed - Zannichellia L.
- Horned Pondweed - Zannichellia Palustris L.
- Horned Spurge - Euphorbia Brachycera Engelm.
- Hornemann's Willowherb - Epilobium Hornemannii Rchb.
- Hornemann's Willowherb - Epilobium Hornemannii Rchb. ssp. behringianum (Hausskn.) Hoch & P.H. Raven
- Hornemann's Willowherb - Epilobium Hornemannii Rchb. ssp. hornemannii
- Hornemannia Racemosa Vahl
- Hornleaf Riverweed - Podostemum Ceratophyllum Michx.
- Hornpod - Mitreola L.
- Hornpoppy - Glaucium Mill.
- Hornschuch's Dung Moss - Tayloria Hornschuchii (Grev. & Arn.) Broth.
- Hornschuch's Molendoa Moss - Molendoa Hornschuchiana (Hook.) Lindb. ex Limpr.
- Hornschuch's Pseudocrossidium Moss - Pseudocrossidium Hornschuchianum (Schultz) R.H. Zander
- Hornwort - Anthoceros Adscendens Lehm. & Lindenb.
- Hornwort - Anthoceros Fusiformis Austin
- Hornwort - Anthoceros L. emend. Prosk.
- Hornwort - Anthoceros Punctatus L.
- Hornwort - Anthoceros Scariosus Austin
- Hornwort - Anthoxanthum L.
- Hornwort - Ceratophyllum L.
- Horrid Herrickia - Eurybia Horrida (Wooton & Standl.) G.L. Nesom
- Horse Chestnut - Aesculus Hippocastanum L.
- Horse Crippler - Echinocactus Texensis Hopffer
- Horse Marmalade - Desmodium Discolor Vogel
- Horse-gentian - Triosteum L.
- Horsebalm - Collinsonia L.
- Horsebrush - Tetradymia Dc.
- Horsebush - Peltophorum Dubia (Spreng.) Taubert
- Horseeye Bean - Mucuna Sloanei Fawc. & Rendle
- Horseeye Bean - Mucuna Sloanei Fawc. & Rendle var. persericea Wilmot-Dear
- Horseeye Bean - Mucuna Sloanei Fawc. & Rendle var. sloanei
- Horseflesh Mahogany - Lysiloma Sabicu Benth.
- Horsefly's Eye - Dopatrium Junceum (Roxb.) Buch.-Ham. ex Benth.
- Horseflyweed - Baptisia Tinctoria (L.) R. Br.
- Horsegram - Macrotyloma Uniflorum (Lam.) Verdc.
- Horsehair Lichen - Bryoria Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Capillaris (Ach.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Cervinula Mot. ex Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Chalybeiformis (L.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Friabilis Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Furcellata (Fr.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Fuscescens (Gyel.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Implexa (Hoffm.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Lanestris (Ach.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Nitidula (Th. Fr.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Pseudocapillaris Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Pseudofuscescens (Gyel.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Salazinica Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Simplicior (Vain.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Spiralifera Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Subcana (Nyl. ex Stizenb.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Tenuis (E. Dahl) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Trichodes (Michx.) Brodo & D. Hawksw.
- Horsehair Lichen - Bryoria Trichodes (Michx.) Brodo & D. Hawksw. ssp. trichodes
- Horsekiller - Zornia Leptophylla (Benth.) Pittier
- Horseradish - Armoracia Rusticana G. Gaertn., B. Mey. & Scherb.
- Horseradishtree - Moringa Oleifera Lam.
- Horseshoe Geranium - Pelargonium Zonale (L.) L'Hér. ex Aiton
- Horseshoe Vetch - Hippocrepis Comosa L.
- Horsetail - Equisetum L.
- Horsetail - Equisetum ×font-queri Rothm.
- Horsetail - Equisetum ×litorale Kühlewein ex Rupr. (pro sp.)
- Horsetail - Equisetum ×mackaii (Newm.) Brichan
- Horsetail - Equisetum ×nelsonii (A.A. Eaton) Schaffn. (pro sp.)
- Horsetail Milkweed - Asclepias Subverticillata (A. Gray) Vail
- Horsetail Paspalum - Paspalum Fluitans (Elliott) Kunth
- Horseweed - Conyza Less.
- Horseweed - Laennecia Cass.
- Horsfieldia Amklaal Kaneh.
- Horsfieldia Nunu Kaneh.
- Horsfieldia Willd.
- Hortulan Plum - Prunus Hortulana L.H. Bailey
- Horungia - Hornungia Rchb.
- Hosackia Alamosana Rose
- Hosackia Americana (Nutt.) Piper
- Hosackia Argophylla A. Gray
- Hosackia Argophylla A. Gray var. decora I.M. Johnst.
- Hosackia Argyraea Greene
- Hosackia Brachycarpa Benth.
- Hosackia Crassifolia Benth.
- Hosackia Cuprea (Greene) Smiley
- Hosackia Cystoides Benth.
- Hosackia Decumbens Benth.
- Hosackia Dendroidea (Greene) Abrams
- Hosackia Denticulata E. Drew
- Hosackia Fremontii (A. Gray) Abrams
- Hosackia Glabra (Vogel) Torr.
- Hosackia Glabra (Vogel) Torr. var. brevialata (Ottley) Abrams
- Hosackia Gracilis Benth.
- Hosackia Grandiflora Benth.
- Hosackia Haydonii Orcutt
- Hosackia Humilis (Greene) Abrams
- Hosackia Incana Torr.
- Hosackia Juncea Benth.
- Hosackia Lathyroides Durand & Hilg.
- Hosackia Leucophaea (Greene) Abrams
- Hosackia Maritima Nutt.
- Hosackia Nevadensis (S. Watson) Parish
- Hosackia Nivea (Greene) S. Watson
- Hosackia Oblongifolia Benth.
- Hosackia Ornithopa Greene
- Hosackia Ornithopa Greene ssp. venusta (Eastw.) Abrams
- Hosackia Parviflora Benth.
- Hosackia Pinnata (Hook.) Abrams
- Hosackia Prostrata Nutt.
- Hosackia Puberula Benth. var. nana A. Gray
- Hosackia Rigida Benth.
- Hosackia Rosea Eastw.
- Hosackia Rubella Nutt.
- Hosackia Sericea Benth.
- Hosackia Sericea Benth. ssp. jepsonii (Ottley) Abrams
- Hosackia Stipularis Benth.
- Hosackia Stipularis Benth. ssp. balsamifera (Kellogg) Abrams
- Hosackia Strigosa Nutt.
- Hosackia Strigosa Nutt. var. hirtella (Greene) H.M. Hall
- Hosackia Subpinnata auct. non (Lag.) Torr. & A. Gray
- Hosackia Sulphurea (Greene) Abrams
- Hosackia Tomentella (Greene) Abrams
- Hosackia Tomentosa Hook. & Arn.
- Hosackia Tomentosa Hook. & Arn. ssp. glabriuscula (Hook. & Arn.) Abrams
- Hosackia Torreyi A. Gray
- Hosackia Wrightii A. Gray
- Hosackia Wrightii A. Gray ssp. multicaulis (Ottley) Abrams
- Hosackia Wrightii A. Gray var. multicaulis Ottley
- Hoskett Meadows Lupine - Lupinus Culbertsonii Greene
- Hoskett Meadows Lupine - Lupinus Culbertsonii Greene ssp. culbertsonii
- Hoskett Meadows Lupine - Lupinus Culbertsonii Greene ssp. hypolasius (Greene) Cox
- Hosokawa's Moerenhoutia - Moerenhoutia Hosokawae (Fukuy.) Tuyama
- Hosokawa's Snakegourd - Trichosanthes Hosokawae Fosberg
- Host Sedge - Carex Hostiana DC.
- Hosta Japonica (Thunb.) Voss, non Tratt., nom. ambig.
- Hosta Tsushimensis N. Fujita
- Hot Springs Fimbry - Fimbristylis Thermalis S. Watson
- Hot Springs Globemallow - Sphaeralcea Polychroma La Duke
- Hottentot Fig - Carpobrotus Edulis (L.) L. Bolus
- Hottentot-bread - Dioscorea Elephantipes (L'Hér.) Engl.
- Hottonia - Hottonia L.
- Hottonia Indica L.
- Houghton's Flatsedge - Cyperus Houghtonii Torr.
- Houghton's Goldenrod - Oligoneuron Houghtonii (Torr. & A. Gray ex A. Gray) G.L. Nesom
- Houghton's Sedge - Carex Houghtoniana Torr. ex Dewey
- Hound's Tongue - Cynoglossum L.
- Houndstongue Hawkweed - Hieracium Cynoglossoides Arv.-Touv.
- Hourglass Peaseed - Sphinctospermum Constrictum (S. Watson) Rose
- House Range Primrose - Primula Cusickiana (A. Gray) A. Gray var. domensis (Kass & S.L. Welsh) N.H. Holmgre
- House's Stitchwort - Minuartia Macrantha (Rydb.) House
- Houseleek - Sempervivum L.
- Houston Meadow-rue - Thalictrum Texanum (A. Gray) Small
- Houston Tansyaster - Rayjacksonia Aurea (A. Gray) R.L. Hartm. & M.A. Lane
- Houstonia Acerosa (A. Gray) A. Gray ex Benth. & Hook. f. ssp. polypremoides (A. Gr
- Houstonia Angustifolia Michx.
- Houstonia Angustifolia Michx. var. filifolia (Chapm.) A. Gray
- Houstonia Angustifolia Michx. var. rigidiuscula A. Gray
- Houstonia Butterwickiae Terrell
- Houstonia Caerulea L. var. faxonorum Pease & A.H. Moore
- Houstonia Calycosa (A. Gray) C. Mohr
- Houstonia Canadensis Willd. ex Roem. & Schult. var. setiscaphia (L.G. Carr) C.F. Reed
- Houstonia Ciliolata Torr.
- Houstonia Fasciculata A. Gray, non Bertol.
- Houstonia Filifolia (Chapm.) Small
- Houstonia Floridana Standl.
- Houstonia Greenei (A. Gray) Terrell
- Houstonia Lanceolata (Poir.) Britton
- Houstonia Longifolia Gaertn. var. compacta Terrell
- Houstonia Longifolia Gaertn. var. glabra Terrell
- Houstonia Longifolia Gaertn. var. tenuifolia (Nutt.) Alph. Wood
- Houstonia Minima Beck
- Houstonia Montana Small
- Houstonia Mullerae (Fosberg) Terrell
- Houstonia Nigricans (Lam.) Fernald
- Houstonia Nigricans (Lam.) Fernald var. floridana (Standl.) Terrell
- Houstonia Nigricans (Lam.) Fernald var. pulvinata (Small) Terrell
- Houstonia Patens Elliott
- Houstonia Polypremoides A. Gray
- Houstonia Polypremoides A. Gray var. bigelovii Greenm.
- Houstonia Pulvinata Small
- Houstonia Purpurea L. var. pubescens Britton
- Houstonia Purpurea L. var. tenuifolia (Nutt.) A. Gray
- Houstonia Pygmaea C.H. Mull. & M.T. Mull.
- Houstonia Rigidiuscula (A. Gray) Wooton & Standl.
- Houstonia Rotundifolia Michx.
- Houstonia Rupicola Greenm.
- Houstonia Salina A. Heller
- Houstonia Setiscaphia L.G. Carr
- Houstonia Tenuifolia Nutt.
- Houstonia Tenuis Small
- Houttuynia - Houttuynia Thunb.
- Hovenia - Hovenia Thunb.
- Howaiaulu Island-daisy - Keysseria Maviensis (H. Mann) Cabrera
- Howard's Alpine Forget-me-not - Eritrichium Howardii (A. Gray) Rydb.
- Howard's Evening Primrose - Oenothera Howardii (A. Nelson) W.L. Wagner
- Howe's Dicranella Moss - Dicranella Howei Renauld & Cardot
- Howe's Hedgehog Cactus - Echinocereus Engelmannii (Parry ex Engelm.) Lem. var. howei L.D. Benson
- Howeia - Howeia Becc.
- Howell's Alkaligrass - Puccinellia Howellii J.I. Davis
- Howell's Bentgrass - Agrostis Howellii Scribn.
- Howell's Biscuitroot - Lomatium Howellii (S. Watson) Jeps.
- Howell's Bluegrass - Poa Howellii Vasey & Scribn.
- Howell's Broomrape - Orobanche Valida Jeps. ssp. howellii Heckard & T.S. Collins
- Howell's Buckwheat - Eriogonum Howellianum Reveal
- Howell's Buckwheat - Johanneshowellia Reveal
- Howell's Camas - Camassia Howellii S. Watson
- Howell's Dicranum Moss - Dicranum Howellii Renauld & Cardot
- Howell's Fawnlily - Erythronium Howellii S. Watson
- Howell's Fleabane - Erigeron Howellii A. Gray
- Howell's Gumweed - Grindelia Howellii Steyerm.
- Howell's Jewelflower - Streptanthus Howellii S. Watson
- Howell's Lewisia - Lewisia Cotyledon (S. Watson) B.L. Rob. var. howellii (S. Watson) Jeps.
- Howell's Lousewort - Pedicularis Howellii A. Gray
- Howell's Lupine - Lupinus Johannis-howellii C.P. Sm.
- Howell's Mariposa Lily - Calochortus Howellii S. Watson
- Howell's Marsh Marigold - Caltha Leptosepala DC. ssp. howellii (Huth) P.G. Sm.
- Howell's Milkvetch - Astragalus Howellii A. Gray
- Howell's Minerslettuce - Montia Howellii S. Watson
- Howell's Onion - Allium Howellii Eastw.
- Howell's Onion - Allium Howellii Eastw. var. howellii
- Howell's Pepperweed - Lepidium Nitidum Nutt. var. howellii C.L. Hitchc.
- Howell's Phacelia - Howellanthus (constance) Walden & R. Patt.
- Howell's Pioneer Rockcress - Arabis Platysperma A. Gray var. howellii (S. Watson) Jeps.
- Howell's Pussytoes - Antennaria Howellii Greene
- Howell's Pussytoes - Antennaria Howellii Greene ssp. howellii
- Howell's Pussytoes - Antennaria Howellii Greene ssp. neodioica (Greene) Bayer
- Howell's Quillwort - Isoetes Howellii Engelm.
- Howell's Reedgrass - Calamagrostis Howellii Vasey
- Howell's Rush - Juncus Howellii F.J. Herm.
- Howell's Saxifrage - Saxifraga Howellii Greene
- Howell's Silverpuffs - Microseris Howellii A. Gray
- Howell's Stitchwort - Minuartia Howellii (S. Watson) Mattf.
- Howell's Thelypody - Thelypodium Howellii S. Watson
- Howell's Thelypody - Thelypodium Howellii S. Watson ssp. howellii
- Howell's Thelypody - Thelypodium Howellii S. Watson ssp. spectabilis (M. Peck) Al-Shehbaz
- Howell's Triteleia - Triteleia Grandiflora Lindl. var. howellii (S. Watson) Hoover
- Howell's Umbrellawort - Tauschia Howellii (J.M. Coult. & Rose) J.F. Macbr.
- Howell's Violet - Viola Howellii A. Gray
- Howell's Yampah - Perideridia Howellii (J.M. Coult. & Rose) Mathias
- Howellia - Howellia A. Gray
- Howelliella - Howelliella Rothm.
- Hoya - Hoya R. Br.
- Huachuca Hawkweed - Hieracium Carneum Greene
- Huachuca Mountain Adder's-mouth Orchid - Malaxis Corymbosa (S. Watson) Kuntze
- Huachuca Mountain Dwarf Mistletoe - Arceuthobium Gillii Hawksw. & Wiens
- Huachuca Mountain Eryngo - Eryngium Phyteumae Delar. f.
- Huachuca Mountain Geranium - Geranium Wislizeni S. Watson
- Huachuca Mountain Indian Paintbrush - Castilleja Patriotica Fernald
- Huachuca Mountain Lupine - Lupinus Huachucanus M.E. Jones
- Huachuca Mountain Milkvetch - Astragalus Hypoxylus S. Watson
- Huachuca Mountain Milkwort - Polygala Piliophora S.F. Blake
- Huachuca Mountain Morning-glory - Ipomoea Plummerae A. Gray
- Huachuca Mountain Ragwort - Senecio Multidentatus Sch. Bip. ex Hemsl.
- Huachuca Mountain Ragwort - Senecio Multidentatus Sch. Bip. ex Hemsl. var. huachucanus (A. Gray) T.M. Barkley
- Huachuca Mountain Rocktrumpet - Mandevilla Brachysiphon (Torr.) Pichon
- Huachuca Mountain Sedge - Carex Leucodonta T. Holm
- Huachuca Mountain Spurge - Euphorbia Macropus (Klotzsch & Garcke) Boiss.
- Huachuca Mountain Stonecrop - Sedum Stelliforme S. Watson
- Huachuca Xanthoparmelia Lichen - Xanthoparmelia Huachucensis (T. Nash) Egan
- Huahekili Uka - Scaevola Kilaueae O. Deg.
- Hualalai Bur Cucumber - Sicyos Lasiocephalus Skottsb.
- Hualalai Hau Kuahiwi - Hibiscadelphus Hualalaiensis Rock
- Hualapai Blazingstar - Mentzelia Hualapaiensis J.J. Schenk, W.C. Hodgs., & L. Hufford
- Huber's Fleabane - Erigeron Huberi S.L. Welsh & N.D. Atwood
- Huber's Pepperweed - Lepidium Huberi S.L. Welsh & Goodrich
- Hubricht's Bluestar - Amsonia Hubrichtii Woodson
- Huckleberry - Gaylussacia Kunth
- Huckleberry Oak - Quercus Vacciniifolia Kellogg
- Huddelson's Locoweed - Oxytropis Huddelsonii A.E. Porsild
- Hudson Bay Currant - Ribes Hudsonianum Richardson var. hudsonianum
- Hudson Bay Eyebright - Euphrasia Hudsoniana Fernald & Wiegand
- Hudson Bay Eyebright - Euphrasia Hudsoniana Fernald & Wiegand var. contracta Sell & Yeo
- Hudson Bay Eyebright - Euphrasia Hudsoniana Fernald & Wiegand var. ramosior Sell & Yeo
- Hudson Bay Sedge - Carex Heleonastes L. f.
- Hudson Bay Sedge - Carex Heleonastes L. f. ssp. heleonastes
- Hudson Bay Sedge - Carex Heleonastes L. f. ssp. neurochlaena (T. Holm) Böcher
- Hudson's Air Fern - Pneumatopteris Hudsoniana (Brack.) Holttum
- Hudsonia Ericoides L. ssp. andersonii Nickerson & Skog
- Hudsonia Ericoides L. ssp. intermedia (Peck) Nickerson & Skog
- Hudsonia Ericoides L. ssp. montana (Nutt.) Nickerson & Skog
- Hudsonia Ericoides L. ssp. tomentosa (Nutt.) Nickerson & Skog
- Hudsonia Intermedia (Peck) Erskine (pro hybr.)
- Hueco Rockdaisy - Perityle Huecoensis A. Powell
- Hueso - Chionanthus Axilliflorus (Griseb.) Stearn
- Hueso Prieto - Chionanthus Holdridgei (Camp & Monachino) Stearn
- Hufelandia Pendula (Sw.) Nees
- Hugelia Densifolia Benth.
- Huger's Carrionflower - Smilax Hugeri (Small) J.B.S. Norton ex Pennell
- Hugeria Erythrocarpa (Michx.) Small
- Hughes's Phacelia - Phacelia Hughesii N.D. Atwood
- Huilia Albocaerulescens (Wulfen) Hertel
- Huilia Cinereoatra (Ach.) Hertel
- Huilia Crustulata (Ach.) Hertel
- Huilia Elegantior (H. Magn.) Hertel
- Huilia Flavocaerulescens (Hornem.) Hertel
- Huilia Glaucophaea (Körb.) Hertel
- Huilia Macrocarpa (DC.) Hertel
- Huilia Melinodes (Körb.) Hertel
- Huilia Nigrocruenta (Anzi) Hertel
- Huilia Panaeola (Ach.) Hertel
- Huilia Platycarpoides (Bagl.) Hertel
- Huilia Soredizodes (Lamy ex Nyl.) Hertel
- Huilia Superba (Körb.) Hertel
- Huilia Tuberculosa (Sm.) P. James
- Huisache Daisy - Amblyolepis Setigera DC.
- Hulsea Caespitosa A. Nelson & Kennedy
- Hulsea Californica Torr. & A. Gray ssp. inyoensis D.D. Keck
- Hulsea Callicarpha (H.M. Hall) S. Watson ex Rydb.
- Hulsea Carnosa Rydb.
- Hulsea Inyoensis (D.D. Keck) Munz
- Hulsea Larsenii (A. Gray) Rydb.
- Hulsea Nana A. Gray var. larsenii A. Gray
- Hulsea Nevadensis Gandog.
- Hulsea Parryi A. Gray
- Hulsea Vestita A. Gray var. callicarpha H.M. Hall
- Hulsea Vestita A. Gray var. pygmaea A. Gray
- Hulsea Volcanica Gandog.
- Hulten's Alkaligrass - Puccinellia Hultenii Swallen
- Hulten's Bryhnia Moss - Bryhnia Hultenii E.B. Bartram
- Hulten's Crabseye Lichen - Ochrolechia Subplicans (Nyl.) Brodo ssp. hultenii (Erichsen) Brodo
- Hulten's Fleabane - Erigeron Hultenii Spongberg
- Hulten's Licorice-root - Ligusticum Scoticum L. ssp. hultenii (Fernald) Calder & Roy L. Taylor
- Hulten's Pitted Lichen - Cavernularia Hultenii Degel.
- Hulten's Saxifrage - Saxifraga Lyallii Engl. ssp. hultenii (Calder & Savile) Calder & Roy L. Taylor
- Hulteniella - Hulteniella Tzvelev
- Hulumoa - Exocarpos Gaudichaudii A. DC.
- Humata Banksii Alston
- Humata Botrychioides Brack.
- Humata Pectinata (Sm.) Desv.
- Humata Pusilla (Mett.) Carruth.
- Humata Repens (L. f.) Diels
- Humboldt Bay Owl's-clover - Castilleja Ambigua Hook. & Arn. ssp. humboldtiensis (D.D. Keck) T.I. Chuang & Hecka
- Humboldt Bedstraw - Galium Muricatum W. Wight
- Humboldt County Milkvetch - Astragalus Agnicidus Barneby
- Humboldt Lily - Lilium Humboldtii Roezl & Leichtlin ex Duch.
- Humboldt Mule-ears - Wyethia Longicaulis A. Gray
- Humboldt River Milkvetch - Astragalus Iodanthus S. Watson
- Humboldt River Milkvetch - Astragalus Iodanthus S. Watson var. iodanthus
- Humboldt Wallflower - Erysimum Menziesii (Hook.) Wettst. ssp. eurekense R.A. Price
- Humboldt's Aspicilia - Aspicilia Humboldtii (Lynge) J.W. Thomson
- Humboldt's Lily - Lilium Humboldtii Roezl & Leichtlin ex Duch. ssp. humboldtii
- Humboldt's Lily - Lilium Humboldtii Roezl & Leichtlin ex Duch. ssp. ocellatum (Kellogg) Thorne
- Humboldt's Willow - Salix Humboldtiana Willd.
- Hummingbird Sage - Salvia Spathacea Greene
- Hummingbird Trumpet - Epilobium Canum (Greene) P.H. Raven
- Hummingbird Trumpet - Epilobium Canum (Greene) P.H. Raven ssp. angustifolium (D.D. Keck) P.H. Raven
- Hummingbird Trumpet - Epilobium Canum (Greene) P.H. Raven ssp. canum
- Hummingbird Trumpet - Epilobium Canum (Greene) P.H. Raven ssp. latifolium (Hook.) P.H. Raven
- Hummock Honeymyrtle - Melaleuca Eleutherostachya F. Muell.
- Humped Bladderwort - Utricularia Gibba L.
- Humulus Americanus Nutt.
- Humulus Lupulus L. ssp. americanus (Nutt.) Á. Löve & D. Löve
- Humulus Scandens auct. non (Lour.) Merr.
- Hungarian Clover - Trifolium Pannonicum Jacq.
- Hungarian Iris - Iris Variegata L.
- Hungarian Lilac - Syringa Josikaea Jacq. f. ex Rchb.
- Hungarian Milkvetch - Astragalus Contortuplicatus L.
- Hungarian Vetch - Vicia Pannonica Crantz
- Hunnemannia - Hunnemannia Sweet
- Hunnewell Pine - Pinus ×hunnewellii Alb.G. Johnson
- Huntsville Vasevine - Clematis Morefieldii Kral
- Hunzikeria - Hunzikeria D'arcy
- Huon Pine - Dacrydium Franklinii Hook. f.
- Hupa Gooseberry - Ribes Marshallii Greene
- Hupeh Cotoneaster - Cotoneaster Hupehensis Rehder & E.H. Wilson
- Huperzia Beitelii Ollgaard, nom. illeg.
- Huperzia Lucidula (Michx.) Trevis. var. tryonii (Mohlenbr.) Mohlenbr.
- Huperzia Mirabilis (Willd.) Holub
- Huperzia Selago (L.) Bernh. ex Schrank & Mart. ssp. arctica (Grossh.) Á. Löve &
- Huperzia Selago (L.) Bernh. ex Schrank & Mart. ssp. chinensis (Christ) Á. Löve &
- Huperzia Selago (L.) Bernh. ex Schrank & Mart. ssp. lucidula (Michx.) Á. Löve &
- Huperzia Selago (L.) Bernh. ex Schrank & Mart. ssp. serrata (Thunb.) Á. Löve & D
- Huperzia Selago (L.) Bernh. ex Schrank & Mart. var. miyoshiana (Makino) Roy L. T
- Huperzia Selago (L.) Bernh. ex Schrank & Mart. var. patens (P. Beauv.) Trevis.
- Huperzia Selago (L.) Bernh. ex Schrank & Mart. var. porophila (Lloyd & Underw.)
- Huperzia Serrata (Thunb.) Trevis. var. dentata (Hillebr.) Kartesz & Gandhi
- Huperzia Serrata (Thunb.) Trevis. var. serrata
- Huperzia Sulcinervia (Spring) Trevis., database artifact
- Huperzia Verticillata auct. non (L. f.) Trevis.
- Huperzia ×helleri (Herter) Kartesz & Gandhi
- Hupilo - Coprosma Menziesii A. Gray
- Huron Green Orchid - Platanthera Huronensis (Nutt.) Lindl.
- Hurricanegrass - Fimbristylis Cymosa R. Br.
- Husk Tomato - Physalis Pubescens L.
- Husk Tomato - Physalis Pubescens L. var. integrifolia (Dunal) Waterf.
- Husk Tomato - Physalis Pubescens L. var. pubescens
- Husnotiella Pringlei (Cardot) Grout
- Husnotiella Revoluta Cardot
- Husnotiella Revoluta Cardot var. palmeri (Cardot) E.B. Bartram
- Husnotiella Torquescens (Cardot) E.B. Bartram
- Hutchins' Ulota Moss - Ulota Hutchinsiae (Sm.) Hammar
- Hutchins' Ulota Moss - Ulota Hutchinsiae (Sm.) Hammar var. hutchinsiae
- Hutchins' Ulota Moss - Ulota Hutchinsiae (Sm.) Hammar var. rufescens (E. Britton) Dix.
- Hutchinsia Calycina Stephan ex Willd. var. americana Regel & Herder
- Hutchinsia Calycina Stephan ex Willd. var. integrifolia Seem.
- Hutchinsia Procumbens (L.) Desv.
- Hutera Cheiranthos (Vill.) Gomez-Campo
- Hutton's Dewberry - Rubus Huttonii L.H. Bailey
- Huuskonen's Phacopsis Lichen - Phacopsis Huuskonenii Rasanen
- Hyacinth - Hyacinthus L.
- Hyacinth Meadow Garlic - Allium Canadense L. var. hyacinthoides (Bush) Ownbey & Aase
- Hyacinth-flower Clematis - Clematis Heracleifolia DC.
- Hyacinth-orchid - Dipodium R. Br.
- Hyacinthbean - Lablab Purpureus (L.) Sweet
- Hyacinthoides - Hyacinthoides Medik.
- Hyacinthoides - Hyacinthoides ×massartiana Geerinck
- Hyacinthoides ×variabilis P.D. Sell, nom. inval.
- Hyacinthus Botryoides L.
- Hybanthus Linearis (Torr.) Shinners
- Hybanthus Portoricensis Urb.
- Hybanthus Verticillatus (Ortega) Baill. var. platyphyllus (A. Gray) Cory & Parks
- Hybanthus Verticillatus (Ortega) Baill. var. verticillatus
- Hybosperma Spinosum Urb.
- Hybrid Acacia - Senegalia Berlandieri × wrightii [unnamed hybrid]
- Hybrid Acacia - Vachellia ×ruthvenii Seigler & Ebinger
- Hybrid Alfalfa - Medicago Hybrida (Pourr.) Trautv.
- Hybrid Balsam Poplar - Populus ×brayshawii B. Boivin
- Hybrid Beardgrass - Bothriochloa Hybrida (Gould) Gould
- Hybrid Blackberry - Rubus Bifrons × ursinus [unnamed hybrid]
- Hybrid Blackberry - Rubus Pensilvanicus × ursinus [unnamed hybrid]
- Hybrid Blackhaw - Viburnum Prunifolium × rufidulum [unnamed hybrid]
- Hybrid Bladder Sedge - Carex Grayi × intumescens [unnamed hybrid]
- Hybrid Blazing Star - Liatris ×freemaniana J. Allison
- Hybrid Blazing Star - Liatris ×macdanieliana J. Allison
- Hybrid Cattail - Typha ×glauca Godr. (pro sp.)
- Hybrid Cherry - Prunus ×yedoensis Matsum. (pro sp.)
- Hybrid Cloakfern - Astrolepis Integerrima (Hook.) Benham & Windham
- Hybrid Common Reed - Phragmites Australis (Cav.) Trin. ex Steud. ssp. americanus × ssp. australis [unnamed
- Hybrid Crack Willow - Salix ×rubens Schrank (pro sp.)
- Hybrid Cypress - ×hesperotropsis Garland & Gerry Moore
- Hybrid Daffodil - Narcissus ×intermedius Loisel.
- Hybrid Dock - Rumex ×acutus L. (pro sp.)
- Hybrid Elm - Ulmus Pumila × rubra [unnamed hybrid]
- Hybrid European Blackberry - Rubus Bifrons × laciniatus [unnamed hybrid]
- Hybrid False Oat - Trisetum Orthochaetum Hitchc.
- Hybrid Floatingheart - Nymphoides Aquatica × cordata [unnamed hybrid]
- Hybrid Fuchsia - Fuchsia Hybrida hort. ex Siebold & Voss
- Hybrid Hawthorn - Crataegus ×media Bechst.
- Hybrid Hemlock - Tsuga ×jeffreyi (Henry) Henry
- Hybrid Hickory - Carya Nutt.
- Hybrid Hickory - Carya ×brownii Sarg.
- Hybrid Hickory - Carya ×collina Laughlin
- Hybrid Hickory - Carya ×demareei Palmer
- Hybrid Hickory - Carya ×dunbarii Sarg.
- Hybrid Hickory - Carya ×laneyi Sarg.
- Hybrid Hickory - Carya ×ludoviciana (Ashe) Little
- Hybrid Hickory - Carya ×nussbaumeri Sarg.
- Hybrid Hickory - Carya ×schneckii Sarg.
- Hybrid Honeylocust - Gleditsia ×texana Sarg. (pro sp.)
- Hybrid Ladyslipper - Cypripedium ×alaskanum P.M. Brown
- Hybrid Ladyslipper - Cypripedium ×andrewsii A.M. Fuller
- Hybrid Ladyslipper - Cypripedium ×andrewsii A.M. Fuller var. favillianum (J.T. Curtis) B. Boivin (pro nm.)
- Hybrid Ladyslipper - Cypripedium ×andrewsii A.M. Fuller var. landonii (Garay) B. Boivin (pro nm.)
- Hybrid Ladyslipper - Cypripedium ×andrewsii A.M. Fuller var. ×andrewsii
- Hybrid Ladyslipper - Cypripedium ×columbianum Sheviak
- Hybrid Locust - Robinia ×ambigua Poir. (pro sp.)
- Hybrid Locust - Robinia ×holdtii Beissn.
- Hybrid Locust - Robinia ×longiloba Ashe (pro sp.)
- Hybrid Locust - Robinia ×margarettiae Ashe (pro sp.)
- Hybrid Lupine - Lupinus Hybridus Lem.
- Hybrid Marram - ×ammocalamagrostis Baltica (Flugge ex Schrad.) P. Fourn.
- Hybrid Meadowbeauty - Rhexia Aristosa × virginica [unnamed hybrid]
- Hybrid Oak - Quercus Alba × virginiana [unnamed hybrid]
- Hybrid Oak - Quercus ×acutidens Torr.
- Hybrid Oak - Quercus ×ashei Trel.
- Hybrid Oak - Quercus ×atlantica Ashe (pro sp.)
- Hybrid Oak - Quercus ×bebbiana C.K. Schneid.
- Hybrid Oak - Quercus ×beckyae Gaynor
- Hybrid Oak - Quercus ×benderi Baenitz
- Hybrid Oak - Quercus ×bernardiensis W. Wolf (pro sp.)
- Hybrid Oak - Quercus ×bimundorum Palmer
- Hybrid Oak - Quercus ×blufftonensis Trel.
- Hybrid Oak - Quercus ×brittonii W.T. Davis (pro sp.)
- Hybrid Oak - Quercus ×byarsii Sudw.
- Hybrid Oak - Quercus ×caduca Trel.
- Hybrid Oak - Quercus ×caesariensis Moldenke
- Hybrid Oak - Quercus ×capesii W. Wolf
- Hybrid Oak - Quercus ×cocksii Sarg.
- Hybrid Oak - Quercus ×columnaris Laughlin
- Hybrid Oak - Quercus ×deamii Trel.
- Hybrid Oak - Quercus ×demareei Ashe
- Hybrid Oak - Quercus ×discreta Laughlin
- Hybrid Oak - Quercus ×diversiloba Tharp ex A. Camus
- Hybrid Oak - Quercus ×egglestonii Trel.
- Hybrid Oak - Quercus ×eplingii C.H. Mull.
- Hybrid Oak - Quercus ×exacta Trel.
- Hybrid Oak - Quercus ×faxonii Trel.
- Hybrid Oak - Quercus ×fernaldii Trel.
- Hybrid Oak - Quercus ×filialis Little
- Hybrid Oak - Quercus ×fontana Laughlin
- Hybrid Oak - Quercus ×ganderi C.B. Wolf
- Hybrid Oak - Quercus ×garlandensis Palmer
- Hybrid Oak - Quercus ×giffordii Trel.
- Hybrid Oak - Quercus ×grandidentata Ewan (pro sp.)
- Hybrid Oak - Quercus ×hawkinsiae Sudw.
- Hybrid Oak - Quercus ×howellii Tucker
- Hybrid Oak - Quercus ×humidicola Palmer
- Hybrid Oak - Quercus ×incomita Palmer
- Hybrid Oak - Quercus ×inconstans Palmer
- Hybrid Oak - Quercus ×introgressa P.M. Thomp.
- Hybrid Oak - Quercus ×jackiana C.K. Schneid.
- Hybrid Oak - Quercus ×jolonensis Sarg.
- Hybrid Oak - Quercus ×leana Nutt. (pro sp.)
- Hybrid Oak - Quercus ×ludoviciana Sarg.
- Hybrid Oak - Quercus ×megaleia Laughlin
- Hybrid Oak - Quercus ×mellichampii Trel. ex Sarg.
- Hybrid Oak - Quercus ×moultonensis Ashe (pro sp.)
- Hybrid Oak - Quercus ×munzii Tucker
- Hybrid Oak - Quercus ×mutabilis Palmer & Steyerm.
- Hybrid Oak - Quercus ×neopalmeri Sudw. ex Palmer
- Hybrid Oak - Quercus ×neotharpii A. Camus
- Hybrid Oak - Quercus ×nessiana Palmer
- Hybrid Oak - Quercus ×organensis Trel.
- Hybrid Oak - Quercus ×oviedoensis Sarg.
- Hybrid Oak - Quercus ×palaeolithicola Trel.
- Hybrid Oak - Quercus ×palmeriana A. Camus
- Hybrid Oak - Quercus ×podophylla Trel.
- Hybrid Oak - Quercus ×rehderi Trel.
- Hybrid Oak - Quercus ×riparia Laughlin
- Hybrid Oak - Quercus ×robbinsii Trel.
- Hybrid Oak - Quercus ×rolfsii Small (pro sp.)
- Hybrid Oak - Quercus ×rudkinii Britton (pro sp.)
- Hybrid Oak - Quercus ×runcinata (A. DC.) Engelm.
- Hybrid Oak - Quercus ×sargentii Rehder
- Hybrid Oak - Quercus ×saulii C.K. Schneid.
- Hybrid Oak - Quercus ×schochiana Dieck ex Palmer
- Hybrid Oak - Quercus ×schuettei Trel.
- Hybrid Oak - Quercus ×smallii Trel.
- Hybrid Oak - Quercus ×stelloides Palmer
- Hybrid Oak - Quercus ×sterilis Trel. ex Palmer
- Hybrid Oak - Quercus ×sterretii Trel.
- Hybrid Oak - Quercus ×subconvexa Tucker
- Hybrid Oak - Quercus ×subfalcata Trel.
- Hybrid Oak - Quercus ×subintegra (Engelm.) Trel.
- Hybrid Oak - Quercus ×substellata Trel.
- Hybrid Oak - Quercus ×tottenii Melvin
- Hybrid Oak - Quercus ×townei Palmer
- Hybrid Oak - Quercus ×tridentata (Engelm. ex A. DC.) Trel. (pro sp.)
- Hybrid Oak - Quercus ×vaga Palmer & Steyerm.
- Hybrid Oak - Quercus ×venulosa Ashe
- Hybrid Oak - Quercus ×wagneri Gaynor
- Hybrid Oak - Quercus ×walteriana Ashe
- Hybrid Oak - Quercus ×willdenowiana (Dippel) Beissner, Schelle & Zabel (pro sp.)
- Hybrid Pine - Pinus Rigida × serotina [unnamed hybrid]
- Hybrid Pine - Pinus Rigida × taeda [unnamed hybrid]
- Hybrid Pine - Pinus Serotina × taeda [unnamed hybrid]
- Hybrid Pine - Pinus ×attenuradiata Stockw. & Righter
- Hybrid Pine - Pinus ×murraybanksiana Righter & Stockw.
- Hybrid Pitcherplant - Sarracenia Rosea × rubra [unnamed hybrid]
- Hybrid Pitcherplant - Sarracenia ×bellii Mellich.
- Hybrid Pitcherplant - Sarracenia ×casei Mellich.
- Hybrid Pitcherplant - Sarracenia ×charlesmoorei Mellich.
- Hybrid Pitcherplant - Sarracenia ×courtii Masters [excluded]
- Hybrid Pitcherplant - Sarracenia ×excellens G. Nicholson (pro sp.) [excluded]
- Hybrid Pitcherplant - Sarracenia ×naczii Mellich.
- Hybrid Plum - Prunus ×orthosepala Koehne (pro sp.)
- Hybrid Plum - Prunus ×palmeri Sarg. (pro sp.)
- Hybrid Plum - Prunus ×slavinii Palmer ex Rehder
- Hybrid Rhododendron - Rhododendron ×bakeri (Lemmon & McKay) Hume (pro sp.)
- Hybrid Rhododendron - Rhododendron ×pennsylvanicum Rehder
- Hybrid Rhododendron - Rhododendron ×vanhoeffeni Abromeit
- Hybrid Rhododendron - Rhododendron ×welleslyanum Waterer ex Rehder
- Hybrid Rock Polypody - Polypodium ×incognitum Cusick
- Hybrid Rose - Rosa ×dulcissima Lunell (pro sp.)
- Hybrid Rose - Rosa ×harisonii Rivers
- Hybrid Rose - Rosa ×housei Erlanson (pro sp.)
- Hybrid Rose - Rosa ×palustriformis Rydb. (pro sp.)
- Hybrid Rose - Rosa ×rudiuscula Greene (pro sp.)
- Hybrid Ryegrass - Lolium ×hybridum Hausskn.
- Hybrid Ryegrass - ×leydeum Barkworth
- Hybrid Ryegrass - ×leydeum Piperi (Bowden) Barkworth
- Hybrid Sedge - Carex Gynodynama × mendocinensis [unnamed hybrid]
- Hybrid Spikerush - Eleocharis ×inaequilatera D.J. Rosen & Chr. Reid
- Hybrid Spruce - Picea ×lutzii Little
- Hybrid Stonecrop - Phedimus Hybridus (L.) 't Hart
- Hybrid Sugar Maple - Acer Leucoderme × saccharum [unnamed hybrid]
- Hybrid Sumac - Rhus ×borealis Greene
- Hybrid Violet - Viola Conspersa × walteri [unnamed hybrid]
- Hybrid Violet - Viola ×bissellii House
- Hybrid Violet - Viola ×brauniae Grover ex Cooperr.
- Hybrid Violet - Viola ×champlainensis House
- Hybrid Violet - Viola ×conjugens Greene (pro sp.)
- Hybrid Violet - Viola ×consobrina House
- Hybrid Violet - Viola ×consocia House
- Hybrid Violet - Viola ×cooperrideri H.E. Ballard
- Hybrid Violet - Viola ×cordifolia (Nutt.) Schwein. (pro sp.)
- Hybrid Violet - Viola ×davisii House
- Hybrid Violet - Viola ×dissita House
- Hybrid Violet - Viola ×eamesii House
- Hybrid Violet - Viola ×eclipes H.E. Ballard
- Hybrid Violet - Viola ×filicetorum Greene (pro sp.)
- Hybrid Violet - Viola ×greenmanii House
- Hybrid Violet - Viola ×hollickii House
- Hybrid Violet - Viola ×insessa House
- Hybrid Violet - Viola ×insolita House
- Hybrid Violet - Viola ×luciae Skottsb.
- Hybrid Violet - Viola ×malteana House
- Hybrid Violet - Viola ×melissifolia Greene
- Hybrid Violet - Viola ×mistura House (pro sp.)
- Hybrid Violet - Viola ×modesta House
- Hybrid Violet - Viola ×mollicula House
- Hybrid Violet - Viola ×mulfordiae Pollard (pro sp.)
- Hybrid Violet - Viola ×napae House
- Hybrid Violet - Viola ×notabilis E.P. Bicknell (pro sp.)
- Hybrid Violet - Viola ×porteriana Pollard (pro sp.)
- Hybrid Violet - Viola ×ravida House
- Hybrid Violet - Viola ×redacta House
- Hybrid Violet - Viola ×robinsoniana House
- Hybrid Violet - Viola ×ryoniae House
- Hybrid Violet - Viola ×slavinii House
- Hybrid Violet - Viola ×subaffinis House
- Hybrid Violet - Viola ×wittrockiana Gams.
- Hybrid Violet - Viola ×wujekii H.E. Ballard
- Hybrid Walnut - Juglans ×intermedia Carrière
- Hybrid Walnut - Juglans ×quadrangulata (Carrière) Rehder (pro sp.)
- Hybrid Willow - Salix ×amoena Fernald
- Hybrid Willow - Salix ×bebbii Gandog.
- Hybrid Willow - Salix ×beschelii B. Boivin
- Hybrid Willow - Salix ×brachypurpurea B. Boivin
- Hybrid Willow - Salix ×conifera Wangenh. (pro sp.)
- Hybrid Willow - Salix ×cryptodonta Fernald (pro sp.)
- Hybrid Willow - Salix ×dieckiana Suksd. (pro sp.)
- Hybrid Willow - Salix ×ehrhartiana Sm. (pro sp.)
- Hybrid Willow - Salix ×glatfelteri C.K. Schneid.
- Hybrid Willow - Salix ×grayi C.K. Schneid.
- Hybrid Willow - Salix ×peasei Fernald (pro sp.)
- Hybrid Willow - Salix ×princeps-ourayi L. Kelso
- Hybrid Willow - Salix ×rubella Bebb
- Hybrid Willow - Salix ×schneiderii B. Boivin
- Hybrid Willow - Salix ×sericans Tausch ex A. Kern.
- Hybrid Willow - Salix ×simulans Fernald (pro sp.)
- Hybrid Willow - Salix ×solheimii E.H. Kelso
- Hybrid Willow - Salix ×waghornei Rydb. (pro sp.)
- Hybrid Yew - Taxus ×media Rehder
- Hydastylus Borealis E.P. Bicknell
- Hydastylus Brachypus E.P. Bicknell
- Hydastylus Californicus (Ker Gawl.) Salisb.
- Hydastylus Elmeri (Greene) E.P. Bicknell
- Hydatica Foliolosa (R. Br.) Small
- Hydatica Petiolaris (Raf.) Small
- Hydnocarpus Anthelminthica Pierre ex Laness., orth. var.
- Hydnocarpus Anthelminthicus Pierre ex Laness., orth. var.
- Hydnocarpus - Hydnocarpus Anthelminticus Pierre ex Lanessan
- Hydnocarpus - Hydnocarpus Gaertn.
- Hydnophytum Horneanum Becc.
- Hydrangea Arborescens L. ssp. discolor (Ser. ex DC.) E.M. McClint.
- Hydrangea Arborescens L. ssp. radiata (Walter) E.M. McClint.
- Hydrangea Arborescens L. var. deamii H. St. John
- Hydrangea Arborescens L. var. discolor Ser. ex DC.
- Hydrangea Arborescens L. var. oblonga Torr. & A. Gray
- Hydrangea Arborescens L. var. sterilis Torr. & A. Gray
- Hydrangea Ashei Harbison
- Hydrangea - Hydrangea L.
- Hydranthelium Rotundifolium (Michx.) Pennell
- Hydrastis - Hydrastis L.
- Hydriastele H. Wendl. & Drude
- Hydrilla - Hydrilla Rich.
- Hydrocharis Cordifolia Nutt.
- Hydrocharis - Hydrocharis L.
- Hydrocharis Spongia Bosc
- Hydrochloa Caroliniensis P. Beauv.
- Hydrocleys - Hydrocleys Rich.
- Hydrocotyle Asiatica L.
- Hydrocotyle Australis J.M. Coult. & Rose
- Hydrocotyle Canbyi J.M. Coult. & Rose
- Hydrocotyle - Hydrocotyle L.
- Hydrocotyle Rotundifolia Lam.
- Hydrocotyle Sibthorpioides Lam. var. oedipoda O. Deg. & Greenw.
- Hydrocotyle Verticillata Thunb. var. triradiata (A. Rich.) Fernald
- Hydrogrimmia Mollis (Bruch & Schimp.) Loeske
- Hydrolea Affinis A. Gray
- Hydrolea Capsularis (L.) Druce
- Hydromystria Laevigata (Humb. & Bonpl. ex Willd.) Hunziker
- Hydromystria Stolonifera G. Mey.
- Hydrophila Aquatica (L.) House
- Hydrophila Drummondii (Torr. & A. Gray) House
- Hydrophila Drummondii sensu (Torr. & A. Gray) House p.p.
- Hydrophila Vaillantii sensu House, non (Willd.) Roth
- Hydrophylax L. f.
- Hydrophylax Maritima L. f. [excluded]
- Hydrophyllum Congestum Wiegand
- Hydrophyllum Occidentale (S. Watson) A. Gray var. watsonii A. Gray
- Hydrophyllum Viridulum G.N. Jones
- Hydrothyria Lichen - Hydrothyria J.l. Russell
- Hydrothyria Lichen - Hydrothyria Venosa J.L. Russell
- Hydrotrida Caroliniana (Walter) Small
- Hyeronima - Hyeronima Allemao
- Hygroamblystegium Fluviatile (Hedw.) Loeske var. orthocladon (P. Beauv.) H.A. Crum, Steere &
- Hygroamblystegium Fluviatile (Hedw.) Loeske var. ovatum Grout
- Hygroamblystegium Irriguum (Hook. & Wilson) Loeske
- Hygroamblystegium Irriguum (Hook. & Wilson) Loeske var. spinifolium (Schimp.) Mönk.
- Hygroamblystegium Macroneuron Grout
- Hygroamblystegium Moss - Hygroamblystegium Loeske
- Hygroamblystegium Moss - Hygroamblystegium Noterophilum (Sull. & Lesq.) Warnst.
- Hygroamblystegium Moss - Hygroamblystegium Tenax (Hedw.) Jenn.
- Hygroamblystegium Moss - Hygroamblystegium Tenax (Hedw.) Jenn. var. spinifolium (Schimp.) Jenn.
- Hygroamblystegium Moss - Hygroamblystegium Tenax (Hedw.) Jenn. var. tenax
- Hygroamblystegium Orthocladon (P. Beauv.) Loeske
- Hygroamblystegium Varium (Hedw.) Mönk.
- Hygrobiella Laxifolia (Hook.) Spruce
- Hygrobiella Spruce
- Hygrohypmum Moss - Hygrohypnum Alpestre (Hedw.) Loeske
- Hygrohypmum Moss - Hygrohypnum Lindb.
- Hygrohypnum Dilitatum (Wilson) Loeske
- Hygrohypnum Eumontanum H.A. Crum, Steere & L.E. Anderson
- Hygrohypnum Luridum (Hedw.) Jenn. ssp. pseudomontanum (Kindb.) Wijk & Margad.
- Hygrohypnum Luridum (Hedw.) Jenn. var. ehlei (Arnell) Wijk & Margad.
- Hygrohypnum Luridum (Hedw.) Jenn. var. julaceum (Schimp.) Podp.
- Hygrohypnum Luridum (Hedw.) Jenn. var. subsphaericarpon (Brid.) C.E.O. Jensen
- Hygrohypnum Moss - Hygrohypnum Closteri (Austin) Grout
- Hygrohypnum Moss - Hygrohypnum Cochlearifolium (Vent. ex De Not.) Broth.
- Hygrohypnum Moss - Hygrohypnum Duriusculum (De Not.) Jamieson
- Hygrohypnum Moss - Hygrohypnum Eugyrium (Schimp.) Loeske
- Hygrohypnum Moss - Hygrohypnum Luridum (Hedw.) Jenn.
- Hygrohypnum Moss - Hygrohypnum Micans (Mitt.) Broth.
- Hygrohypnum Moss - Hygrohypnum Molle (Hedw.) Loeske
- Hygrohypnum Moss - Hygrohypnum Ochraceum (Turner ex Wilson) Loeske
- Hygrohypnum Moss - Hygrohypnum Styriacum (Limpr.) Broth.
- Hygrohypnum Moss - Hygrohypnum Subeugyrium (Renauld & Cardot) Broth.
- Hygrohypnum Novae-caesareae (Austin) Grout
- Hygrohypnum Ochraceum (Turner ex Wilson) Loeske var. filiforme (Limpr.) Amann
- Hygrohypnum Ochraceum (Turner ex Wilson) Loeske var. flaccidum (Milde) Amann
- Hygrohypnum Ochraceum (Turner ex Wilson) Loeske var. uncinatum (Milde) Loeske
- Hygrohypnum Palustre Loeske
- Hygrohypnum Palustre Loeske var. ehlei (Arnell) Grout
- Hygrohypnum Palustre Loeske var. julaceum (Schimp.) Loeske
- Hygrohypnum Palustre Loeske var. subsphaericarpon (Brid.) Loeske
- Hygrohypnum Polare (Lindb.) Loeske var. falcatum (Bryhn) Broth.
- Hygrohypnum Pseudomontanum (Kindb.) Grout
- Hygrohypnum Smithii (Sw.) Broth. var. goulardii (Schimp.) Wijk & Margad.
- Hygrohypnum Subeugyrium (Renauld & Cardot) Broth. var. occidentale (Cardot & Thér.) Grou
- Hygrophila Brasiliensis (Spreng.) Lindau
- Hygrophila - Hygrophila Triflora (Roxb.) Fosberg & Sachet
- Hygrophila Portoricensis Nees
- Hylocomiastrum Moss - Hylocomiastrum Fleisch.
- Hylocomiastrum Moss - Hylocomiastrum Pyrenaicum (Spruce) Fleisch.
- Hylocomiastrum Moss - Hylocomiastrum Umbratum (Hedw.) Fleisch.
- Hylocomium Alaskanum (Lesq. & James) Austin
- Hylocomium Brevirostre (Brid.) Schimp.
- Hylocomium Feather Moss - Hylocomium Schimp.
- Hylocomium Giganteum Perss., non E.B. Bartram, nom. nud.
- Hylocomium Proliferum (Brid.) Lindb.
- Hylocomium Pyrenaicum (Spruce) Lindb.
- Hylocomium Splendens (Hedw.) Schimp. var. alaskanum (Lesq. & James) Limpr.
- Hylocomium Splendens (Hedw.) Schimp. var. gracilius (Boul.) Husn.
- Hylocomium Splendens (Hedw.) Schimp. var. obtusifolium (Geh.) Par.
- Hylocomium Splendens (Hedw.) Schimp. var. tenue Sharp
- Hylocomium Umbratum (Hedw.) Schimp.
- Hylodesmum Glutinosum (Muhl. ex Willd.) H. Ohashi & R.R. Mill
- Hylodesmum Nudiflorum (L.) H. Ohashi & R.R. Mill
- Hylotelephium Cauticola (Praeger) H. Ohba
- Hylotelephium Sieboldii (Sweet ex Hook.) H. Ohba. [excluded]
- Hymenachne Acutigluma auct. non (Steud.) Gilliland
- Hymenaea - Hymenaea L.
- Hymenatherum Neomexicanum A. Gray
- Hymenatherum Pentachaetum DC.
- Hymenatherum Tagetoides (Torr. & A. Gray) A. Gray
- Hymenelia Arctica (Lynge) Lutzoni
- Hymenelia Ceracea (Arnold) Poelt & Vezda
- Hymenelia Euplotica (Ach.) Lutzoni
- Hymenelia Heteromorpha (Krempelh.) Lutzoni
- Hymenelia Lacustris (With.) M. Choisy
- Hymenelia Lichen - Hymenelia Krempelh.
- Hymenelia Melanocarpa (Krempelh.) Arnold
- Hymenelia Ochrolemma (Vain.) Gowan & Ahti
- Hymenelia Rhodopsis (Sommerf.) Lutzoni
- Hymenocallis Bidentata Small
- Hymenocallis Caroliniana auct. non (L.) Herbert
- Hymenocallis Caymanensis Herb.
- Hymenocallis Collieri Small
- Hymenocallis Declinata (Jacq.) M. Roem.
- Hymenocallis Eulae Shinners
- Hymenocallis Eulae auct. non Shinners
- Hymenocallis Floridana (Raf.) Morton
- Hymenocallis Floridana (Raf.) Morton ssp. amplifolia Traub
- Hymenocallis Galvestonensis (Herb.) Baker
- Hymenocallis Humilis S. Watson
- Hymenocallis Keyensis Small
- Hymenocallis Kimballiae Small
- Hymenocallis Laciniata Small
- Hymenocallis Moldenkiana Traub
- Hymenocallis Palusvirensis Traub
- Hymenocallis Punta-gordensis Traub , orth. var.
- Hymenocallis Traubii Moldenke
- Hymenocarpos Circinnatus (L.) Savi
- Hymenocarpos Savi
- Hymenochaeta Triqueter (L.) Nakai
- Hymenoclea Fasciculata A. Nelson
- Hymenoclea Pentalepis Rydb.
- Hymenoclea Salsola Torr. & A. Gray var. patula (A. Nelson) K.M. Peterson & Payne
- Hymenodium Crinitum (L.) Fée
- Hymenolobus Procumbens (L.) Nutt. ex Schinz & Thell.
- Hymenopappus Arenosus A. Heller
- Hymenopappus Carolinensis (Lam.) Porter
- Hymenopappus Cinereus Rydb.
- Hymenopappus Corymbosus Torr. & A. Gray
- Hymenopappus Eriopodus A. Nelson
- Hymenopappus Filifolius Hook. var. alpestris (Maguire) Shinners
- Hymenopappus Flavomarginatus I.M. Johnst. [excluded]
- Hymenopappus Gloriosus A. Heller
- Hymenopappus - Hymenopappus L'hér.
- Hymenopappus Lugens Greene
- Hymenopappus Luteus Nutt.
- Hymenopappus Pauciflorus I.M. Johnst.
- Hymenopappus Polycephalus Osterh.
- Hymenopappus Robustus Greene
- Hymenopappus Scabiosaeus L'Hér. var. artemisiifolius (DC.) Gandhi & R.D. Thomas
- Hymenopappus Scabiosaeus L'Hér. var. riograndensis (B.L. Turner) Gandhi
- Hymenophyllum Baldwinii D.C. Eaton
- Hymenophyllum Ciliatum (Sw.) Sw.
- Hymenophyllum Contortum auct. non Bosch
- Hymenophyllum Crispum auct. non Kunth
- Hymenophyllum Elegantulum Bosch
- Hymenophyllum Elegantulum Bosch var. petiolulatum Morton
- Hymenophyllum Fendlerianum auct. non Sturm
- Hymenophyllum Polyanthos (Sw.) Sw. var. protrusum (Hook.) Farw.
- Hymenophyllum Protrusum Hook.
- Hymenophysa Pubescens C.A. Mey.
- Hymenosporum Flavum (Hook.) F. Muell.
- Hymenosporum R. Br. ex F. Muell.
- Hymenostomum Inoperculatum H.A. Crum
- Hymenostomum Microstomum (Hedw.) R. Br.
- Hymenostomum Rostellatum auct. Amer.
- Hymenostomum Tortile (Schwägr.) Bruch & Schimp.
- Hymenostylium Curvirostre Mitt.
- Hymenostylium Moss - Hymenostylium Brid.
- Hymenostylium Moss - Hymenostylium Insigne (Dix.) Podp.
- Hymenostylium Moss - Hymenostylium Recurvirostre (Hedw.) Dix.
- Hymenostylium Recurvirostre (Hedw.) Dix. var. insigne (Dix.) E.B. Bartram
- Hymenostylium Recurvirostre (Hedw.) Dix. var. latifolium (J.E. Zetterst.) Wijk & Margad.
- Hymenostylium Scabrum (Lindb.) Loeske
- Hymenoxys Acaulis (Pursh) K.F. Parker
- Hymenoxys Acaulis (Pursh) K.F. Parker var. arizonica (Greene) K.F. Parker
- Hymenoxys Acaulis (Pursh) K.F. Parker var. caespitosa (A. Nelson) K.F. Parker
- Hymenoxys Acaulis (Pursh) K.F. Parker var. epunctata (A. Nelson) Cronquist
- Hymenoxys Acaulis (Pursh) K.F. Parker var. glabra (A. Gray) K.F. Parker
- Hymenoxys Acaulis (Pursh) K.F. Parker var. ivesiana (Greene) K.F. Parker
- Hymenoxys Acaulis (Pursh) K.F. Parker var. lanata (Greene) Cronquist
- Hymenoxys Acaulis (Pursh) K.F. Parker var. nana S.L. Welsh
- Hymenoxys Argentea (A. Gray) K.F. Parker
- Hymenoxys Argentea (A. Gray) K.F. Parker var. ivesiana (Greene) Cronquist
- Hymenoxys Brandegeei Porter ex A. Gray
- Hymenoxys Depressa (Torr. & A. Gray ex A. Gray) S.L. Welsh & Reveal
- Hymenoxys Glabra (Nutt.) Shinners
- Hymenoxys Grandiflora (Torr. & A. Gray ex A. Gray) K.F. Parker
- Hymenoxys Herbacea (Greene) Cusick
- Hymenoxys Ivesiana (Greene) K.F. Parker
- Hymenoxys Linearifolia Hook.
- Hymenoxys Microcephala (A. Gray) Bierner
- Hymenoxys Olivacea Cockerell
- Hymenoxys Richardsonii (Hook.) Cockerell var. utahensis Cockerell
- Hymenoxys Scaposa (DC.) K.F. Parker
- Hymenoxys Scaposa (DC.) K.F. Parker var. argyrocaulon K.F. Parker
- Hymenoxys Scaposa (DC.) K.F. Parker var. glabra (Nutt.) K.F. Parker
- Hymenoxys Scaposa (DC.) K.F. Parker var. linearis (Nutt.) K.F. Parker
- Hymenoxys Scaposa (DC.) K.F. Parker var. villosa Shinners
- Hymenoxys Torreyana (Nutt.) K.F. Parker
- Hymenoxys Turneri K.F. Parker
- Hyophila Moss - Hyophila Brid.
- Hyophila Moss - Hyophila Involuta (Hook.) A. Jaeger
- Hyophila Riparia (Austin) Fleisch.
- Hyophila Stanfordensis (Steere) A.J.E. Sm. & H. Whitehouse
- Hyophila Tortula (Schwägr.) Hampe
- Hyophiladelphus Agrarius (Hedw.) R.H. Zander
- Hyophilopsis Sprengelii (Schwägr.) H.A. Crum
- Hyoseris Biflora Walter
- Hyoseris Minima L.
- Hyoseris Virginica L.
- Hyparrhenia Anthistirioides (Hochst. ex A. Rich.) Stapf
- Hyparrhenia Claessensii Robyns
- Hyparrhenia - Hyparrhenia Filipendula (Hochst.) Stapf
- Hyparrhenia Pilgeriana C.E. Hubb.
- Hypecoum Grandiflorum Benth.
- Hypecoum - Hypecoum L.
- Hypelate - Hypelate P. Br.
- Hyperbaena - Hyperbaena Miers ex Benth.
- Hypericum Acutifolium Elliott
- Hypericum Aegypticum L.
- Hypericum Aegypticum L. ssp. webbii (Spach) N. Robson
- Hypericum Ambiguum Elliott
- Hypericum Apocynifolium Small
- Hypericum Aspalathoides Willd. p.p.
- Hypericum Aureum W. Bartram
- Hypericum Beanii N. Robson
- Hypericum Bissellii B.L. Rob.
- Hypericum Buckleyi M.A. Curtis, orth. var.
- Hypericum Canadense L. var. galiiforme Fernald
- Hypericum Canadense L. var. magninsulare Weath.
- Hypericum Canadense L. var. majus A. Gray
- Hypericum Cerastoides (Spach) N. Robson
- Hypericum Coris L.
- Hypericum Degeneri Fosberg
- Hypericum Densiflorum Pursh var. lobocarpum (Gattinger ex J.M. Coult.) Svens.
- Hypericum Denticulatum Walter var. acutifolium (Elliott) S.F. Blake
- Hypericum Denticulatum Walter var. ovalifolium (Britton) S.F. Blake
- Hypericum Denticulatum Walter var. recognitum Fernald & B.G. Schub.
- Hypericum Erythraeae (Spach) Steud., orth. var.
- Hypericum Formosum Kunth [excluded]
- Hypericum Formosum Kunth ssp. scouleri (Hook.) C.L. Hitchc.
- Hypericum Formosum Kunth var. nortoniae (M.E. Jones) C.L. Hitchc.
- Hypericum Formosum Kunth var. scouleri (Hook.) J.M. Coult.
- Hypericum Fraseri (Spach) Steud.
- Hypericum Galioides Lam. var. pallidum C. Mohr
- Hypericum Glomeratum Small
- Hypericum Grandifolium Choisy
- Hypericum Harperi auct. non R. Keller p.p.
- Hypericum Hircinum L.
- Hypericum Hypericoides (L.) Crantz var. multicaule (Michx. ex Willd.) Fosberg
- Hypericum Mutilum L. ssp. boreale (Britton) J.M. Gillett
- Hypericum Mutilum L. var. latisepalum Fernald
- Hypericum Mutilum L. var. parviflorum (Willd.) Fernald
- Hypericum Nortoniae M.E. Jones
- Hypericum Oklahomense Palmer
- Hypericum Opacum Torr. & A. Gray
- Hypericum Patulum Thunb.
- Hypericum Patulum Thunb. var. henryi J.H. Veitch ex Bean
- Hypericum Petiolatum Walter, non L.
- Hypericum Punctatum Lam. var. pseudomaculatum (Bush) Fernald
- Hypericum Pyramidatum Aiton
- Hypericum Reductum (Svens.) P. Adams
- Hypericum Reflexum L. f.
- Hypericum Repens L.
- Hypericum Roeperianum G.W. Schimp. ex A. Rich.
- Hypericum Rumeliacum Boiss.
- Hypericum Spathulatum (Spach) Steud.
- Hypericum Sphaerocarpum Michx. var. turgidum (Small) Svens.
- Hypericum Splendens Small
- Hypericum Stans (Michx. ex Willd.) P. Adams & N. Robson
- Hypericum Stragulum P. Adams & N. Robson
- Hypericum Subpetiolatum E.P. Bicknell ex Small
- Hypericum Tubulosum Walter
- Hypericum Tubulosum Walter var. walteri (J.G. Gmel.) Lott
- Hypericum Turgidum Small
- Hypericum Uralum Buch.-Ham. ex D. Don
- Hypericum Virginicum L.
- Hypericum Virginicum L. var. fraseri (Spach) Fernald
- Hypericum Walteri J.G. Gmel.
- Hypericum Webbii (Spach) Steud.
- Hyperphyscia Lichen - Hyperphyscia Adglutinata (Flörke) H. Mayrh. & Poelt
- Hyperphyscia Lichen - Hyperphyscia Minor (Fée) D.D. Awasthi
- Hyperphyscia Lichen - Hyperphyscia Müll. Arg.
- Hyperphyscia Lichen - Hyperphyscia Syncolla (Tuck. ex Nyl.) Kalb
- Hyphaene Benguelensis Welw. ex H. Wendl.
- Hyphaene - Hyphaene Gaertn.
- Hypnum Abietinum Hedw.
- Hypnum Andoi A.J.E. Sm.
- Hypnum Arcuatum Lindb.
- Hypnum Arcuatum Lindb. var. americanum Renauld & Cardot
- Hypnum Arcuatum Lindb. var. demissum Schimp.
- Hypnum Arcuatum Lindb. var. elatum Schimp.
- Hypnum Bridelianum H.A. Crum, Steere & L.E. Anderson
- Hypnum Crista-castrensis Hedw.
- Hypnum Cupressiforme Hedw. var. brevisetum Schimp.
- Hypnum Cupressiforme Hedw. var. ericetorum Schimp.
- Hypnum Cupressiforme Hedw. var. imponens (Hedw.) Guim.
- Hypnum Cupressiforme Hedw. var. mammillatum Brid.
- Hypnum Depressulum Müll. Hal.
- Hypnum Ericetorum (Schimp.) Loeske
- Hypnum Fastigiatum Brid.
- Hypnum Haldanianum Grev.
- Hypnum Lindbergii Mitt. var. americanum (Renauld & Cardot) Whitehouse
- Hypnum Lindbergii Mitt. var. demissum (Schimp.) Loeske
- Hypnum Lindbergii Mitt. var. elatum (Schimp.) R.S. Williams
- Hypnum Molluscoides Kindb.
- Hypnum Molluscum Hedw.
- Hypnum Molluscum Hedw. var. molluscoides (Broth. ex Paris) Grout
- Hypnum Moss - Hypnum Callichroum Funck ex Brid.
- Hypnum Moss - Hypnum Circinale Hook.
- Hypnum Moss - Hypnum Cupressiforme Hedw.
- Hypnum Moss - Hypnum Cupressiforme Hedw. var. cupressiforme
- Hypnum Moss - Hypnum Cupressiforme Hedw. var. julaceum Brid.
- Hypnum Moss - Hypnum Cupressiforme Hedw. var. lacunosum Brid.
- Hypnum Moss - Hypnum Cupressiforme Hedw. var. resupinatum (Taylor) Schimp.
- Hypnum Moss - Hypnum Cupressiforme Hedw. var. subjulaceum Molendo
- Hypnum Moss - Hypnum Fertile Sendtn.
- Hypnum Moss - Hypnum Geminum (Mitt.) Lesq. & James
- Hypnum Moss - Hypnum Hamulosum Schimp.
- Hypnum Moss - Hypnum Hedw.
- Hypnum Moss - Hypnum Imponens Hedw.
- Hypnum Moss - Hypnum Jutlandicum Holmen & Warncke
- Hypnum Moss - Hypnum Mammillatum (Brid.) Loeske
- Hypnum Moss - Hypnum Pallescens (Hedw.) P. Beauv.
- Hypnum Moss - Hypnum Pallescens (Hedw.) P. Beauv. var. pallescens
- Hypnum Moss - Hypnum Pallescens (Hedw.) P. Beauv. var. protuberans (Brid.) Austin
- Hypnum Moss - Hypnum Plicatulum (Lindb.) A. Jaeger
- Hypnum Moss - Hypnum Pratense (Rabenh.) Koch ex Spruce
- Hypnum Moss - Hypnum Procerrimum Molendo
- Hypnum Moss - Hypnum Subimponens Lesq.
- Hypnum Pallescens (Hedw.) P. Beauv. var. reptile (Michx.) Husn.
- Hypnum Patientiae Lindb. ex Milde
- Hypnum Patientiae Lindb. ex Milde var. americanum (Renauld & Cardot) Renauld & Car
- Hypnum Patientiae Lindb. ex Milde var. demissum (Schimp.) A. Jaeger
- Hypnum Patientiae Lindb. ex Milde var. elatum (Schimp.) A. Jaeger
- Hypnum Plicatile (Mitt.) Lesq. & James
- Hypnum Protuberans Brid.
- Hypnum Ravaudii Boul. ssp. fastigiatum (Brid.) Wijk & Margad.
- Hypnum Reptile Michx.
- Hypnum Revolutum (Mitt.) Lindb. var. dolomiticum (Milde) Mönk.
- Hypnum Revolutum (Mitt.) Lindb. var. subjulaceum Bryhn
- Hypnum Subimponens Lesq. var. cristulum Kindb.
- Hypnum Subplicatile Limpr.
- Hypnum Vaucheri Lesq. var. coelophyllum (Molendo) Molendo
- Hypocenomyce Anthracophila (Nyl.) P. James & Gotth. Schneid.
- Hypochaeris Brasiliensis (Less.) Benth. & Hook. ex Griseb. var. tweedyi (Hook. & Arn.) Ba
- Hypochaeris Elata auct. non (Weddell) Griseb.
- Hypochaeris Tweediei Hook. & Arn.
- Hypochaeris Tweedyi Hook. & Arn., orth. var.
- Hypochoeris L., orth. var.
- Hypoderris - Hypoderris R. Br. ex Hook.
- Hypoestes - Hypoestes Sol. ex R. Br.
- Hypogon Verticillata (Baldw.) House, non Raf.
- Hypogon Verticillata Raf.
- Hypogymnia Apinnata Goward & McCune
- Hypogymnia Bitteriana (Zahlbr.) Rasanen
- Hypogymnia Elongata (Hillm.) Rass.
- Hypogymnia Encausta (Sm.) Walt. Watson
- Hypogymnia Intestiniformis (Vill.) Rasanen
- Hypogymnia Oroarctica Krog
- Hypogymnia Pseudophysodes (Asah.) Rass.
- Hypogymnia Subphysodes (Krempelh.) Filson
- Hypolepis Flaccida (Hillebr.) W.J. Rob. [excluded]
- Hypolepis Punctata auct. non (Thunb.) Mett.
- Hypolytrum Berteroi Spreng.
- Hypolytrum Dissitiflorum Steud.
- Hypolytrum Nemorum sensu Parham, non Spreng.
- Hypolytrum Pers.
- Hypopitys Americana (DC.) Small
- Hypopitys Fimbriata (A. Gray) Howell
- Hypopitys Insignata E.P. Bicknell
- Hypopitys Lanuginosa (Michx.) Nutt.
- Hypopitys Latisquama Rydb.
- Hypopitys Monotropa Crantz
- Hypopterygium Moss - Hypopterygium Brid.
- Hypopterygium Moss - Hypopterygium Tamariscinum (Hedw.) Brid.
- Hypotrachyna Costaricensis (Nyl.) Hale
- Hypotrachyna Formosana (Zahlbr.) Hale
- Hypotrachyna Lichen - Hypotrachyna (vain.) Hale
- Hypotrachyna Lichen - Hypotrachyna Croceopustulata (Kurok.) Hale
- Hypotrachyna Lichen - Hypotrachyna Densirhizinata (Kurok.) Hale
- Hypotrachyna Lichen - Hypotrachyna Dentella (Hale & Kurok.) Hale
- Hypotrachyna Lichen - Hypotrachyna Ensifolia (Kurok.) Hale
- Hypotrachyna Lichen - Hypotrachyna Gondylophora (Hale) Hale
- Hypotrachyna Lichen - Hypotrachyna Imbricatula (Zahlbr.) Hale
- Hypotrachyna Lichen - Hypotrachyna Laevigata (Sm.) Hale
- Hypotrachyna Lichen - Hypotrachyna Livida (Taylor) Hale
- Hypotrachyna Lichen - Hypotrachyna Osseoalba (Vain.) Park & Hale
- Hypotrachyna Lichen - Hypotrachyna Polydactyla (Krog & Swinscow) T. Nash
- Hypotrachyna Lichen - Hypotrachyna Producta Hale
- Hypotrachyna Lichen - Hypotrachyna Prolongata (Kurok.) Hale
- Hypotrachyna Lichen - Hypotrachyna Pseudosinuosa (Asah.) Hale
- Hypotrachyna Lichen - Hypotrachyna Pulvinata (Fée) Hale
- Hypotrachyna Lichen - Hypotrachyna Pustulifera (Hale) Skorepa
- Hypotrachyna Lichen - Hypotrachyna Revoluta (Flörke) Hale
- Hypotrachyna Lichen - Hypotrachyna Subsaxatilis (de Lesd.) Hale
- Hypotrachyna Lichen - Hypotrachyna Thysanota (Kurok.) Hale
- Hypotrachyna Rachista (Hale) Hale
- Hypotrachyna Riparia McCune
- Hypotrachyna Taylorensis (M.E. Mitch.) Hale
- Hypoxis Hirsuta (L.) Coville var. leptocarpa (Engelm. & A. Gray) Brackett
- Hypoxis Leptocarpa (Engelm. & A. Gray) Small
- Hypoxis Longii Fernald
- Hypoxis Micrantha Pollard
- Hyptis Alata (Raf.) Shinners var. stenophylla Shinners
- Hyptis Americana (Aubl.) Urb.
- Hyptis Mutabilis (A. Rich.) Briq. var. spicata (Poit.) Briq.
- Hyptis Radiata Willd.
- Hyptis Scoparia Poit.
- Hyssop - Hyssopus Officinalis L.
- Hyssop Loosestrife - Lythrum Hyssopifolium L.
- Hyssopleaf Asphead - Aspicarpa Hyssopifolia A. Gray
- Hyssopleaf Fleabane - Erigeron Hyssopifolius Michx.
- Hyssopleaf Fleabane - Erigeron Hyssopifolius Michx. var. hyssopifolius
- Hyssopleaf Hedgenettle - Stachys Aspera Michx.
- Hyssopleaf Hedgenettle - Stachys Hyssopifolia Michx.
- Hyssopleaf Pepperweed - Lepidium Hyssopifolium Desv.
- Hyssopleaf Sandmat - Chamaesyce Hyssopifolia (L.) Small
- Hyssopleaf Thoroughwort - Eupatorium Hyssopifolium L.
- Hyssopleaf Thoroughwort - Eupatorium Hyssopifolium L. var. calcaratum Fernald & B.G. Schub.
- Hyssopleaf Thoroughwort - Eupatorium Hyssopifolium L. var. hyssopifolium
- Hyssopleaf Thoroughwort - Eupatorium Hyssopifolium L. var. laciniatum A. Gray
- Hyssopus - Hyssopus L.
- Hystrix Californica Bol. ex Thurb.
- Hystrix Hystrix (L.) Millsp., nom. inval.
- Hystrix Patula Moench
- Hystrix Patula Moench var. bigeloviana (Fernald) Deam
Copyright ©2022 - All rights reserved.