Tetradymia canescens DC. var. inermis (Rydb.) Payson

http://plants.usda.gov/� ache, as a yellow dye for wool and in various religious ceremonies (Native American Ethnobotany Database).

Description

General: Sunflower Family (Asteraceae). Spineless horsebrush is a native, deciduous, taprooted, much-branched shrub, 2-8 dm (7.9-31.5 in) tall and usually as wide as it is tall. Leaves and flower bracts are white-tomentose (dense, white wooliness) and the plants have a gray-white color. Leaves are linear or oblanceolate 1-3 cm (0.39-1.17 in) long and 1-4mm (0.04-0.16 in) wide with a prominent midrib. Flowers are in terminal clusters and are yellow to cream-colored. The flower heads usually have 4 bracts. Stems are short, stout and silvery canescent until maturity then become glabrous. Achenes are 3-4 mm (0.12-0.16 in) long, usually densely silky with a well developed pappus. Chromosome number is 2n = 60, seldom 90. (Whitson et al. 1996; Cronquist et al. 1994). Spineless horsebrush is commonly confused with various sagebrush and rabbitbrush species before flowering. Distribution: Spineless horsebrush is found from Montana south into New Mexico and west to the Pacific coast and north into British Columbia, Canada (PLANTS Database). For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site. Spineless horsebrush begins growth in mid-April, flower buds form in early to mid-June and begins flowering in mid-July in the Upper Snake River Plains of Idaho. Seeds are ripe in mid-August and leaf drop occurs in early October. Blooming occurs in late July or early August in southern California and northern Arizona (Scher, 2001). Habitat: Spineless horsebrush is found in sagebrush (Artemisia), pinyon-juniper (Pinus-Juniperus spp.), ponderosa pine (Pinus ponderosa), mountain brush, mixed conifer, and quaking aspen (Populus tremuloides) plant communities (Scher, 2001). In Idaho, Utah, Montana and Nevada it is commonly associated with green rabbitbrush (Chrysothamnus viscidiflorus) and big sagebrush (A. tridentata). Threetip sagebrush (A tripartita), rubber rabbitbrush (Chrysothamnus nauseous) and Idaho fescue (Festuca idahoensis) are also associated with spineless horsebrush in Idaho and Montana. Needleandthread (Hesperostipa comata) and indian ricegrass (Achnatherum hymenoides) are associated species in Montana and Nevada). Other common associates include antelope bitterbrush (Purshia tridentata), mountain snowberry (Symphoricarpos oreophilus), black sagebrush (A. nova), bluebunch wheatgrass (Pseudoroegneria spicata), bottlebrush squirreltail (Elymus elymoides), desert peach (Prunus andersonii), Mormon tea (Ephedra viridis) and Thurber needlegrass (Achnatherum thurberianum). Spineless horsebrush is considered primarily a weedy, early seral species (Scher, 2001).

Adaptation

Spineless horsebrush is adapted to dry, open places on plains, ridges and hills ranging in elevation from 1,300-9,700 feet (396-2956m). In the southern part of its range, it is found at higher elevations and in the northern areas at lower elevations. It is adapted to medium to coarse textured soils with a pH of 7 to 8 and found most commonly in gravelly or sandy loam soils with 5-12 inches (127-305mm) annual precipitation (Scher, 2001). It is not tolerant of saline conditions (PLANTS database).

Establishment

Information on the establishment of horsebrush in scientific literature is limited. The PLANTS database reports there are 120,000 seeds per pound. Some germination will occur without pretreatment but germination is greatly enhanced by pre-chilling for 4 to 6 weeks (Young and Young, 1992). Attempts using plant tissue culture to develop plants for hard-rock mine land reclamation have been unsuccessful (King et al., 2009). It is a fire resistant shrub. After a fire, the plant responds by rapid sprouting from adventitious buds on the root crown. It also reproduces abundantly from seed following fire. These responses following fire often result in dense stands of spineless horsebrush, and can result in its dominance of sagebrush-grass plant communities that are burned with a frequency of 20 to 25 years (Scher, 2001).

Management

All species of Tetradymia should be considered toxic. Sheep that feed on spineless horsebrush following or in conjunction with consumption of black sagebrush (A. nova) and then exposed to bright sunlight may develop a characteristic swelling of the lips, ears, and face, commonly referred to as “bighead”. Sheep grazing spineless horsebrush in the absence of black sagebrush may still die without developing bighead but suffer from swollen, engorged liver with severe fatty changes and low grade nephritis (inflammation of nephrons) of the kidney along with hemorrhaging of the sub-skin and organ linings. Sheep may also experience abortions from consuming spineless horsebrush (Panter et al., 2011). Most sheep losses occur during stormy periods when sheep change their grazing habits as they are trailed through areas with heavy infestations of spineless horsebrush and desirable forage is lacking. Hungry/thirsty sheep may also eat toxic amounts of spineless horsebrush after they are watered. The plant is especially dangerous during the bud stage (Panter et al., 2011). Poisoning has resulted in losses of as many as 1,000 sheep at a time (Scher, 20010). The best management advice is to avoid these conditions or situations as much as possible. Fire exclusion on desert rangelands has tended to favor sagebrush over fire-tolerant shrubs such as spineless horsebrush. Increased wildfire frequencies due to invasion of annual grasses may favor spineless horsebrush. If management objectives are to reduce spineless horsebrush, fire treatment is not generally recommended as it may result in the species becoming dominant (Scher, 2001).

Pests and Potential Problems

There are no known pests of spineless horsebrush.

Environmental Concerns

Concerns , Use soil moisture sensors to measure the soil moisture of Tetradymia canescens DC. var. inermis (Rydb.) Payson.

Concerns

Spineless horsebrush is a native species that can increase on areas subject to frequent wildfire. An economical method for the control of spineless horsebrush has not been developed (Panter et al., 2011; Evans and Young, 1978).

Control

Mechanical treatments must kill roots 4-6 inches deep for effective control. 2,4-D LV ester is recommended only for spot treatment to control spineless horsebrush. The recommended rate is 2.5 lb acid equivalent per acre, applied early in spring when plants are actively growing. Chemical re-treatment each year may be necessary to control this plant (Pacific Northwest Weed Management Handbook). Be sure to read and follow herbicide label directions. Please contact your local agricultural extension specialist or county weed specialist to learn what works best in your area and how to use it safely. Always read label and safety instructions for each control method. Trade names and control measures appear in this document only to provide specific information. USDA NRCS does not guarantee or warranty the products and control methods named, and other products may be equally effective.

Seed and Plant Production

Plant Production

Plant Production

Information on the successful establishment of spineless horsebrush is not available. Poor value for grazing, the potential for spread following fire, and its toxic properties to sheep make it undesirable in the plant production industry. Cultivars, Improved, and Selected Materials (and area of origin) There are currently no commercial releases of spineless horsebrush. Wildland collections are typically not available from commercial sources. Contract collection for small quantities is possible with costs exceeding $100 per pound.

References

Cronquist, A., Holmgren, A. Holmgren N., Reveal, J., Holmgren, P. Asterales. Intermountain Flora. Vascular Plants of the Intermountain West, U.S.A. Volume Five. The New York Botanical Garden, Bronx, New York. 496 p. Evans, R., and Young, J. 1978. Effectiveness of Rehabilitation Practices Following Wildfire in a Degraded Big Sagebrush-Downy Brome Community. Journal of Range Management. 31(3). p185-188. King, S., King, M., Jennings, S., Neuman, D. 2009. Using Plant Tissue Culture to Develop Plants with Acid Soil, Heavy Metal Tolerance, Potentially Useful for Hard-Rock Mine Land Reclamation. Paper presented at the 2009 National Meeting of the American Society of Mining and Reclamation, Billings, MT, Revitalizing the Environment: Proven Solutions and Innovative Approaches May 30 – June 5, 2009. R.I. Barnhisel (Ed.) Published by AMSR, Lexington, KY. p 673-688 Krysl, L., Hubbert, M., Sowell, B., Plumb, G., Jewett, M., Smith, M., and Waggoner, J. 1984. Horses and Cattle Grazing in the Wyoming Red Desert, I.

Food

Habits and Dietary Overlap. Journal of

Range

Management 37 (1). P 72-76. Machado, S., Tuck, B., McNab, S., Maley, J, and. Igo, J. 2006. Alternative Crops for the Columbia Basin. Oregon State University Extension Service. EM 8914. 25 p. Native American Ethnobotany. A Database of Foods, Drugs, Dyes and Fibers of Native American Peoples Derived from Plants. University of Michigan, College of Arts, Sciences, and Letters http://herb.umd.umich.edu/ (Accessed March 27, 2012) Pacific Northwest Weed Management Handbook. Horsebrush, gray or Spineless (Tetradymia canescens). http://pnwhandbooks.org (Accessed March 28, 2012) Panter, K., Ralphs, M., Pfister, J., Gardner, D., Stegelmeier, B., Lee, S., Welch, K., Green, B., Davis, T., Cook, D. 2011. Plants Poisonous to Livestock in the Western States. United States Department of Agriculture, Agricultural Research Service. Agriculture Information Bulletin Number 415. 120 p. PLANTS Database. Tetradymia canescens. [Online]. http://plants.usda.gov. U.S. Department of Agriculture, Natural Resources Conservation Service. (Accessed March 26, 2012). Scher, J. 2001. Tetradymia canescens. In: Fired Effects Information System [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. http://www.fs.fed.us/database/feis (Accessed March 26, 2012) Young, J. and Young C. 1992. Seeds of Woody Plants in North America. Dioscorides Press, Portland, Oregon. 407 p. Whitson, T., Burrill, L., Dewey, S., Cudney, D., Nelson, B., Lee, R., Parker, R. 1996. Weeds of the West, 5th Edition. The Western Society of Weed Science in cooperation with the Western United States Land Grant Universities Cooperative Extension Services. 630 p. Prepared By: Loren St. John, USDA NRCS Plant Materials Center, Aberdeen, ID Derek Tilley, USDA NRCS Plant Materials Center, Aberdeen, ID Citation St. John, L. and D. Tilley. 2012. Plant Guide for spineless horsebrush (Tetradymia canescens). USDA-Natural Resources Conservation Service, Aberdeen Plant Materials Center. Aberdeen, Idaho 83210. Published April 2012 Edited: 04Apr2012ls;04Apr2012djt;16Apr2012jab;24Apr2012gm For more information about this and other plants, please contact your local NRCS field office or

Plant Traits

Growth Requirements

Temperature, Minimum (°F)	17
Adapted to Coarse Textured Soils	Yes
Adapted to Fine Textured Soils	No
Adapted to Medium Textured Soils	Yes
Anaerobic Tolerance	None
CaCO3 Tolerance	High
Cold Stratification Required	No
Drought Tolerance	High
Fertility Requirement	Low
Fire Tolerance	None
Frost Free Days, Minimum	200
Hedge Tolerance	Medium
Moisture Use	Low
pH, Maximum	8.0
pH, Minimum	7.0
Planting Density per Acre, Maxim	150
Planting Density per Acre, Minim	100
Precipitation, Maximum	11
Precipitation, Minimum	5
Root Depth, Minimum (inches)	6
Salinity Tolerance	None
Shade Tolerance	Intolerant

Morphology/Physiology

Bloat	None
Toxicity	Severe
Resprout Ability	Yes
Shape and Orientation	Erect
Active Growth Period	Spring, Summer, Fall
C:N Ratio	High
Coppice Potential	No
Fall Conspicuous	No
Fire Resistant	Yes
Flower Color	Yellow
Flower Conspicuous	No
Foliage Color	White-Gray
Foliage Porosity Summer	Moderate
Foliage Porosity Winter	Porous
Foliage Texture	Fine
Fruit/Seed Conspicuous	No
Nitrogen Fixation	None
Low Growing Grass	No
Lifespan	Moderate
Leaf Retention	No
Known Allelopath	No
Height, Mature (feet)	4.0
Height at 20 Years, Maximum (fee	4
Growth Rate	Slow
Growth Form	Multiple Stem
Fruit/Seed Color	Brown

Reproduction

Vegetative Spread Rate	None
Small Grain	No
Seedling Vigor	Low
Seed Spread Rate	Moderate
Fruit/Seed Period End	Winter
Seed per Pound	120000
Propagated by Tubers	No
Propagated by Sprigs	No
Propagated by Sod	No
Propagated by Seed	Yes
Propagated by Corm	No
Propagated by Container	Yes
Propagated by Bulb	No
Propagated by Bare Root	Yes
Fruit/Seed Persistence	Yes
Fruit/Seed Period Begin	Fall
Fruit/Seed Abundance	High
Commercial Availability	Contracting Only
Bloom Period	Late Summer
Propagated by Cuttings	Yes

Suitability/Use

Veneer Product	No
Pulpwood Product	No
Protein Potential	Low
Post Product	No
Palatable Human	No
Palatable Graze Animal	Low
Palatable Browse Animal	Low
Nursery Stock Product	No
Naval Store Product	No
Lumber Product	No
Fodder Product	No
Christmas Tree Product	No
Berry/Nut/Seed Product	No

Tetradymia canescens DC. var. inermis (Rydb.) Payson