Houndstongue (Cynoglossum officinale) is not only a toxic plant that contains alkaloids, but also a noxious weed that is increasing over much of North America. The plant spreads from bur-like seeds that cling to wildlife, livestock and humans, and invades disturbed areas. Houndstongue is generally unpalat- able when growing on rangelands, but lactating cows and horses may eat green houndstongue at times. When houndstongue contaminates hay, it is readily eaten by cattle and horses, and is quite toxic.