Hoary Tansyaster

Scientific Name: Machaeranthera canescens (Pursh) A. Gray

Plant Guide

Alternate Names

Common Names: Purple aster Scientific Names: Dieteria canescens

Description

General: Sunflower family (Asteraceae). Hoary tansyaster is a short-lived perennial forb with pale to dark purple flowers. Plants are 15 to 75 cm (6 to 30 in) tall with diffuse branching. Leaves are about 5 cm (2 in) long and 6 mm (0.25 in) wide, oblong or lance shaped with entire to sharply toothed margin. Flower heads have many subtending bracts that reflex away from the flower at the tip (Welsh et al., 2003). Flower heads and vegetation are very sticky and heavily scented. Bracts are white and membranous at the bottom and green at the tip. The pappus of the achene is dirty white and hair-like. There are approximately 1.3 million seeds/lb based on seed counts conducted by Aberdeen Plant Materials Center (Tilley and St. John, 2010). Distribution: Hoary tansyaster occurs throughout western North America from British Columbia to Saskatoon, south to California, Arizona and Colorado. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site. Habitat: Hoary tansyaster is common in plant communities from shadscale desert and Wyoming big sage sagebrush shrub communities on the valley floors to mountain big sagebrush, aspen and limber pine communities moving up-slope to higher elevations. Plants can be readily found flowering in late summer in numerous habitats, but primarily in valley bottoms and other dry areas. Hoary tansyaster is very common in low seral degraded and disturbed sites and has been considered by some as a weedy species in meadows and rangelands (Whitson et al., 1996).

Adaptation

Hoary tansyaster is adapted to medium to coarse textured, well drained soils with a pH of 6.0 to 8.4 (Borden and Black, 2005; Tilley and St. John, 2010). Hoary tansyaster requires full exposure to sunlight, and a minimum 10 inch rooting depth. The species is commonly found in areas receiving 20 to 150 cm (8 to 60 in.) of annual precipitation.

Uses

Restoration/reclamation: Hoary tansyaster is an early colonizer of rangelands and disturbed sites. It is commonly found on roadsides and gravel pits competing with invasive plants such as cheatgrass (Bromus tectorum) and knapweed species (Centaurea spp). It can be planted to enhance species diversity in rangeland seedings throughout the western United States.

Ethnobotanical

Plants were used by Navajo Indians to treat nose and throat troubles (Moerman, 1998). Wildlife: Hoary tansyaster can be used as part of a native forb component in rangeland and wildland seedings to increase biodiversity, improve wildlife habitat, and provide food for numerous birds and mammals. Hoary tansyaster is readily visited by pollinators and other insect species. It is considered an important species for sage grouse during brood rearing because of its insect associations. Insect surveys on hoary tansyaster plots at the Aberdeen Idaho Plant Materials Center showed visitation by sweat bees (Halictus spp.), green sweat bees (Agapostemon spp.), European honey bees (Apis mellifera), bee flies (Bombilidae) and cabbage white butterflies (Pieris spp.). Natural Resources Conservation Service Plant Guide A green sweat bee (Agapostemon sp.) visiting hoary tansyaster. Photo by Derek Tilley

Status

Please consult the PLANTS Web site (http://plants.usda.gov/) and your State Department of Natural Resources for this plant’s current status (e.g., threatened or endangered species, state noxious status, and wetland indicator values).

Planting Guidelines

Parkinson and DeBolt (2005) observed 77% germination of seed that had been pre-chilled in dampened blotter paper at 4° C for 35 days, Seed field establishment at the Aberdeen PMC indicates that pre-chilling may not be necessary for germination, A common garden study comparing 9 populations of hoary tansyaster from Idaho and Utah had establishment percentages ranging from 41 to 87% (Tilley and St, John, 2010) from seed that was field-planted in November and allowed to undergo natural stratification, Seed should be drilled or broadcast seeded in late fall into a firm, weed-free seed bed at a depth of 0 to 6 mm (0 to 0,25 in), For a pure stand, target delivery of 20 to 30 pure live seeds (PLS) per square foot, seed at a rate of 2 lbs (0,9 kg) PLS per acre, If seeding as part of a mix, adjust seeding rate to the desired percentage of the mixture, Broadcast seedings should be followed with a cultipacker to ensure good seed to soil contact, Seed should be mixed with a dilutent such as rice hulls to assist seed flow through seeding equipment, When calculating rice hull amounts based on seed bushel weights, it is important to determine the condition of the seed, Hoary tansyaster seed which has not had the pappus removed has a bushel weight of approximately 3 lb/bushel, Seed that has been processed to remove the pappus weighs approximately 20 to 24 lb/bushel, Use soil moisture sensors to measure the soil moisture of Hoary Tansyaster.,

Management

When planted in a native reclamation seed mix, it will be a minor component of the establishing plant community; therefore management should be based on other key species in the mixture.

Pests and Potential Problems

Moth caterpillars from the genus Cucillia were observed on observational plots at Aberdeen, Idaho. These were seen eating flower heads, but did not appear to do extensive damage to the plots or decrease seed production significantly (Tilley and St. John, 2010). A Cucillia moth caterpillar feeding on hoary tansyaster flower heads. Photo by Derek Tilley

Environmental Concerns

Concerns

Concerns

There are no known environmental concerns associated with hoary tansyaster.

Seeds and Plant Production

Plant Production

Plant Production

Seed production fields of hoary tansyaster can be hand-planted into weed barrier fabric at 9 to 18 inch plant spacing or mechanically seeded into larger field plantings at 30 to 36 inch row spacing at 0.35 lb PLS/ac. Planting timing is important with hoary tansyaster. We have found that late summer (August) seedings result in reduced annual weed competition. Fields planted in spring or early summer did not produce a crop during the first year but did produce the following year and died that winter. Fields planted in the fall produced crops the following 2 years. Plants grown in weed barrier fabric at Aberdeen, Idaho (an 8- 12 inch mean annual rainfall zone) required no supplemental irrigation. Drill seeded fields received 10 cm (4 in) supplemental irrigation in late April and again in mid-May. Flowering begins in late summer and continues for several weeks into the autumn. Seed can be harvested by hand, flail-vac, direct combined, or by using a vacuum harvester (Bair and Tilley 2010).