This page is graphic intense and may take a while to load. Many species of Astragalus are not poisonous and are good rangeland forage plants. However, within the same species, concentrations of toxicants can vary widely from plant to plant so all locoweeds and milk vetches should be approached with caution and assumed potentially dangerous to livestock. Their leaves are alternate and pinnately compound.
Flowers are leguminous and the fruit is a legume pod with kidney shaped seeds.
The pod is often conspicuously enlarged causing the seeds to rattle in it when ripe, hence the common names, rattlebox and rattleweed, that are often assigned to it. The keel petal of Oxytropis tends to be long and pointed whereas that of Astragalus tends to be blunter. Leaves and seeds are the usual source of poisoning, but are rarely eaten do to its strong odor and unpleasant taste. Poisoning can occur when hungry animals are on sparse pasture with Jimsonweed infestation. Most animal poisoning results from feed contamination.