Disturbed soils and waste areas. Tolerates dry conditions well and is often planted to help control soil erosion.
Non-ruminants - pigs, horses, poultry are most likley to be affected. Crown vetch poisoning in horses has been suspected but not well documented!
Crown vetch contains the toxin beta-nitropropionic acid (3-NPA) primarily in the leaves and growing stems. Ruminants are able to detoxify the 3-NPA in their rumens, while simple stomached animals cannot. The 3-NPA once absorbed will cause methemoglobinemia.
The seeds also contain various cardenolides that may cause cardiac conduction disturbances if quantities of the seeds are consumed.
Perennial herbs, with deep taproots, and branching and trailing stems up to 4-5 feet in length. Leaves alternate, odd-pinnate, 3-8 inches long, usually hairless, with up to 25, lanceolate leaflets. Pink to white flowers are produced in the leaf axils, with 5-20 flowers on each stalk. Pea-like pods contain numerous cylindical brown seeds.
Incoordination, staggering gait initially in the hind quarters.
Removing crown vetch from the diet and feeding alfalfa results in recovery.
Potential for heart irregularity if the seeds are consumed in quantity.
Rapid respiratory rate, difficulty in breathing if methemoglobin levels are high.
Crown vetch has similar nutritive value to alfalfa. Concerns about its potential toxicity for horses makes it a poor pasture plant where hay may be made from the pasture.
Crown vetch is often used for erosion control as it is a tough perennial with deep roots to hold the soil.
1. Mraz M et al. Inhibition of Na, K-ATPase by glycosides from Coronilla varia. Planta Med 58: 467-468, 1992.
2. Moyer BG et al. Corollin, coronillin, and coronarian: three new 3-nitropropanol-D-glucopyranoses from Cornollia varia. Phytochem 16: 375-377, 1977.