Locoweed, also known as crazyweed or milkvetch, is a toxic plant that grows in arid regions of North and South America. It is a type of legume that is commonly consumed by livestock, causing them to exhibit abnormal behavior and decreased productivity due to the presence of alkaloids in the plant. Other synonyms for locoweed include trembles, woolly loco, loco grass, and loco weed. These names all refer to the plant's ability to cause neurological symptoms in animals, such as muscle tremors, lack of coordination, and even hallucinations. Despite its toxic nature, locoweed is sometimes used medicinally in small doses to treat heart and lung conditions.