Scientific Name: Gutierrezia sarothrae
Distribution: Western United States and Western Canada
Type of Poison: Saponins and sesquiterpenes
Signs of Poisoning:
Growth Characteristics: Broom snakeweed is a bushy, short-lived, native, perennial shrub or subshrub that grows from 8 to 28 inches in height. It flowers August to October and reproduces solely from seeds. Maximum life span is approximately 20 years.
Flowers/Inflorescence: Numerous heads are arranged in a flat-topped cluster, which is rounded and loose. The flower heads are small, with yellow ray flowers. The bracts are leathery, shiny, and green-tipped.
Fruits/Seeds: Fruit is oval and covered with chaffy scales. Seeds are brown and densely hairy.
Leaves: Leaves are folded, alternate, and threadlike with entire margins. Glands on the leaves do produce resin, making the leaves slightly sticky.
Stems: Twigs are erect, thin, flexible, green to brown, and can be hairy or smooth. Trunk is short with brown bark which is shreddy and smooth. Stems die back in the winter giving the plant its broom-like appearance.
Sheep and cattle have been poisoned in large numbers from eating broom snakeweed; however, most losses occur in cattle. Broom snakeweed grows on drier range areas. Its presence in large amounts is indicative of overgrazing. It may grow during the fall if moisture is adequate; however, growth usually occurs in early spring. Broom snakeweed is much more toxic when growing on sandy soil than on loam soils (referred to as hard soils).
Death may occur, but the principal result of poisoning is abortion. The plant is most toxic during leaf formation. During this time, cattle readily eat broom snakeweed, especially if other feed is scarce. The amount of broom snakeweed needed to cause death or abortion in cattle varies greatly. Cows near term may give birth to small, weak calves that may survive if properly cared for. Many cows that abort have a persistently retained placenta. These should be treated by a veterinarian. Factors affecting dosage include site of growth and stage of growth.
Ranges should be properly managed so as to avoid excessive infestation of broom snakeweed. Cattle should not be grazed where there is an abundance of broom snakeweed growing on sandy soil during the time rapid growth is taking place, especially if there is a scarcity of other feed. Poisoned cows should be removed from broom snakeweed areas and given nutritious feed until they recover.
L.F. James, R.F. Keeler, A.E. Johnson, M.C. Williams, E.H. Cronin, and J.D. Olsen. Plants Poisonous to Livestock in the Western States. U.S. Department of Agriculture, Agriculture Information Bulletin 415, 90 pp. 1980.
Pratt, Mindy S. Broom snakeweed. Range Plants of Utah. 2008. Utah State University Extension Service. 1 July 2009. http://extension.usu.edu/rangeplants/htm/broom-snakeweed