Scientific Name: Lupinus spp.
Distribution: Throughout the United States, Canada, and Mexico
Type of Poison: Alkaloids
Signs of Poisoning:
Growth Characteristics: A complex group of erect to ascending forbs, 10 to 24 inches tall, with one to several stems growing from a shortly branching taproot. Flowers June to August, fruits mature July to September. It reproduces from seeds.
Flowers/Inflorescence: Flowers are small and spurred at the base; color can range from white to purple. They are attached to the stem by a slender stalk (raceme). Each flower has five large stamens and five small stamens.
Fruits/Seeds: Legume (pea pod), somewhat flattened, usually hairy, bearing two to 12 seeds per pod.
Leaves: Palm-shaped with finger-like segments. They can be hairy to silky and silvery on both surfaces.
Lupine is widespread, growing from valley bottoms to high mountain areas. It is adapted to a broad range of soil textures but is most abundant in coarse-textured and well-drained soils. There are both annual and perennial species. Perennials usually start growth fairly early in the spring, flower in June, and form seeds in July or August.
Sheep in the western United States are frequently poisoned by feeding on lupine in the seed stage. Losses may be especially heavy when hungry sheep are trailed through lupine ranges in late summer. Sheep have been poisoned by eating lupine plants that have been cut and dried. Cows may give birth to calves with skeletal defects if the cows ingest certain lupine species during early gestation.
Poisonous species of lupine are dangerous from the time they start growth in the spring until they dry up in the fall. Younger plants are more dangerous than older plants; however, plants in the seed stage in late summer are especially dangerous because of the high alkaloid content of the seeds.
The amount of lupine that will kill an animal varies with the species and stage of plant growth. A sheep that is getting good forage may not be affected by occasionally eating just one-eighth to one-fourth pounds of lupine, even if the lupine includes seed pods. But a sheep is usually poisoned if it eats that much daily for three or four days.
Cattle may be poisoned by eating 1 to 1 1/2 pounds of lupine without other forage. Smaller amounts are poisonous if cattle eat lupine daily for three to seven days. Crooked legs and other congenital deformities occur in newborn calves if cows graze certain species of lupine (L. sericeus, L. caudatus, and L. laxiflorus) between the 40th and 70th days after breeding. Abortions may occur at any stage of the gestation period.
Losses can be reduced by keeping hungry animals away from lupine patches in the early growth stage and in late summer when the plant is in the highly toxic seed stage, as well as from dense plant stands at all times. Supplemental feeding is beneficial, especially when animals are trailed through lupine ranges.
If cows in the 40th to 70th days of gestation are kept from lupine in its very early growth or mature seed stage, most deformities can be prevented. The congenital deformity hazard is minimal at other gestation periods and when the plant is in early flower stage or after pods have shattered and seeds have dropped.
There is no known treatment for lupine poisoning. Affected animals should not be moved until signs of poisoning have disappeared.
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. Lupine. Range Plants of Utah. 2008. Utah State University Extension Service. 28 August 2009. http://extension.usu.edu/rangeplants/htm/lupine