Purshia tridentata

Antelope bitterbrush

Rosaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Magnoliophyta (Flowering plants). Class - Magnoliopsida. Order - Rosales. Family - Roaceae (Rose family). Genus -Purshia DC. ex. Poir. Species - Purshia tridentata (Pursh) DC.

Ecology: Antelope bitterbrush (Purshia tridentata) appears in several mesic habitat types. Plant communities with antelope bitterbrush include range types such as antelope bitterbrush-bluebunch wheatgrass (Pseudoroegneria spicata), antelope bitterbrush-Idaho fescue (Festuca idahoensis), other steppe vegetation, and tree-dominated types such as ponderosa pine (Pinus ponderosa) forest and juniper (Juniperus spp.) woodland.

Identification

General: Medium to tall shrub, 1-2 (3) m tall; stems erect, freely and rigidly branched, twigs woolly-hairy, especially when young.

Leaves: Alternate, deciduous, in small bundles on short lateral spur-shoots, wedge-shaped, mostly 1-2 cm long, 3-toothed at the tip, silvery-greenish and hairy on the upper surface, grey-woolly beneath, the margins rolled under.

Flowers: Inflorescence of single, short-stalked flowers at ends of short, lateral, leafy spur-shoots; corollas yellow to cream, wheel-shaped, the petals 5, egg- to spoon-shaped, 5-9 mm long, early-deciduous; calyces bell-shaped, woolly- or cobwebby-hairy and stalked-glandular, 5-lobed, the lobes oblong-egg-shaped, 3-4 mm long; ovaries superior; stamens about 25.

Fruits: Large achenes, about 15 mm long including the persistent style, ellipsoid-spindle-shaped, somewhat leathery, velvety-hairy and glandular; seeds 1, black, pear-shaped, 6-8 mm long.

Threats

Foragers: Antelope bitterbrush (Purshia tridentata) is important browse for wildlife and livestock. Pronghorn, mule deer, elk, bighorn sheep, and moose utilize antelope bitterbrush extensively. Mule deer use of antelope bitterbrush peaks in September, when antelope bitterbrush may compose 91 percent of the diet. Winter use is greatest during periods of deep snow [201]. In northwestern Nevada and northeastern California, antelope bitterbrush is a critical winter food for mule deer. Domestic livestock and mule deer may compete for antelope bitterbrush in late summer, fall, and/or winter. Cattle prefer antelope bitterbrush from mid-May through June and again in September and October. Antelope bitterbrush seed is a large part of the diets of rodents, especially deer mice and kangaroo rats.

Fire: Antelope bitterbrush (Purshia tridentata) is very susceptible to fire kill. It is considered a weak sprouter and is often killed by summer or fall fire. Antelope bitterbrush in some areas may sprout after light-severity spring fire.

Pathogens: Diseases associated with bitterbrush include root rot, root and stem wilt, and root-stem canker. Seedlings have been damaged by damping off (a disease caused by fungi).

Reproduction

Establishment: Natural establishment of antelope bitterbrush occurs in years with good seed production when rodents cache seed and do not use all of the caches. Moisture is necessary the first few years of seedling growth for establishment. Late fall or winter seeding is recommended and competition can be a problem for establishment. Seeds should be drilled about 1 inch deep at a rate of 1/2 to 2 (3) pounds per acre. Rates are doubled if broadcasting and seeds do need to be covered. In California, pretreatment with hydrogen peroxide is required to break dormancy for spring seeding and seedlings are susceptible to late frosts.

Seedlings: Bitterbrush seedlings are often transplanted on critical sites. In such castes, moisture must be adequate to ensure survival in the first year. Oneyear-old bare-root or containerized seedling stock, 6 to 24 inches tall, is recommended. Rodents normally cache seeds within 50 to 75 feet of an existing seed source.

Species Distribution

Citation

E-Flora of British Columbia
In Klinkenberg, Brian. (Editor) 2015. E-Flora BC: Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 08/02/2017 11:15:56 AM ]

USDA Plants Database
USDA, NRCS. 2017. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.
Distribution Map photo credit

USFS Plant Database
Zlatnik, Elena. 1999. Purshia tridentata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/plants/shrub/purtri/all.html [2017, February 8].

Calflora
Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. [web application]. 2017. Berkeley, California: The Calflora Database [a non-profit organization].

Burke Museum of Natural History and Culture
Burke Museum. 2017. Purshia tridentata [Online]. University of Washington.
Photo credit: 2005, Ben Legler, 2012 Craig Althen