Milkvetch poisoning may be mistaken for larkspur poisoning. Wasatch milkvetch is a perennial that is found on rolling hillsides above 200 meters. It grows 15 to 25 cm high. Flowers of Wasatch milkvetch resemble sweet peas. They vary in color from creamy white to shades of violet.
Toxicity is caused by both inhibition of cellular metabolism and nitrite oxidization of hemoglobin.
Over 260 North American Astragalus species and varieties contain varying amount of these nitro-toxins. Where and When it Grows Milkvetches grow throughout much of North America. Most of the poisonous species grow on the meadows and forests of the Rocky Mountain States and in the semiarid regions of the Southwest. Milkvetches emerge from late April to June, depending on elevation and snowmelt. As plants mature and dry, they decrease in toxicity until they are nontoxic when they are dry.