Scientific Name: Sarcobatus vermiculatus
Distribution: Western United States and Western Canada
Type of Poison: Sodium and potassium oxalates
Signs of Poisoning:
Growth Characteristics: Greasewood is a monoecious shrub (male and female flowers are separate, but on the same plant), growing 2 to 8 feet tall, erect or spreading, and many branched. It flowers June to August and reproduces from seeds and sprouts.
Flowers/Inflorescence: Flowers are unisexual. The numerous male flowers are borne on fleshy, cone-like terminal spikes, whereas female flowers form singly or in pairs in the axils of leaf-like bracts and are wing-like. Flowers are green, tinged with red. The fruit is a small, coriaceous achene, which is winged at the middle and green to tan or reddish. Fruit contains small brown seeds.
Leaves: Leaves of greasewood are round, linear, and fleshy, with entire margins. They are bright green and often have a crust of salt that can be tasted. The leaves are shed in winter.
Stems: Twigs are spreading, many branched, rigid, white to tan, and spiny. Trunk bark is yellowish-gray to light brown with deep grooves.
Greasewood is adapted to the heavy saline soils of semiarid regions. It is found on the floodplains, along dry washes and gullies, and in similar areas.
Greasewood starts growing in early spring. The leaves remain succulent until fall, when they freeze, dry, and drop off. Buds remain on plants most of the year. The toxic substances in greasewood are found in the leaves of the plant. Greasewood increases in toxicity as the growing season advances.
Greasewood is a range shrub that livestock can eat safely in moderate amounts with other forage. Death occurs when livestock eat large amounts in a short period of time. Poisoning occurs in sheep and cattle. Signs of poisoning may develop four to six hours after an animal eats a toxic amount of greasewood. Greasewood poisoning in livestock is similar to that caused by halogeton.
A sheep may die if it eats as much as 2 pound of green leaves and fine stems in a short period without other forage. Cattle may die after eating 3 to 4 pounds of greasewood in a short period. Losses may be high in the fall, when sheep eat large quantities of leaves that have fallen to the ground.
Do not introduce livestock into heavy stands of greasewood unless it can be done slowly to allow time to adapt to the toxic substance in the plant, usually two to three days. Make sure animals are full when first allowed to graze greasewood. Supply adequate water and a good variety of forage.
There is no known treatment for greasewood poisoning.
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. Greasewood. Range Plants of Utah. 2008. Utah State University Extension Service. 24 July 2009. http://extension.usu.edu/rangeplants/htm/greasewood