Oxytropis lambertii commonly known as purple locoweed,[1] Colorado locoweed,[2] Lambert's crazy weed,[3] or Lambert’s Locoweed[4] is a species of flowering plant in the legume family.
It is native to grasslands in the Canadian Prairie of central Canada and in the mid-west and Great Plains of the United States from Texas to Manitoba and west to Arizona and Montana.[5]
Oxytropis lambertii is a perennial herb producing a patch of basal leaves around the root crown, and several showy erect inflorescences. The leaf is compound with several silvery-green leaflets. The inflorescence produces several flowers, each borne in a tubular purple or pinkish calyx of sepals covered thinly in silver hairs. The pealike flower corolla is reddish or bluish purple with a lighter patch at the base of the banner. The fruit is a cylindrical legume pod.
The Oxytropis lambertii plant is one of the locoweeds most frequently implicated in livestock poisoning.[6] The toxin is called swainsonine. Research suggests that the plant itself may not be toxic, but becomes toxic when inhabited by endophytic fungi of the genus Embellisia, which produce swainsonine.[7]