Milkweed

monarch caterpillar

milkweed, (genus Asclepias), genus of about 140 species of herbaceous perennial flowering plants belonging to the dogbane family Apocynaceae (formerly in Asclepiadaceae). Milkweeds are found throughout North and South America, and several are cultivated as ornamentals. Many milkweed butterflies, including monarch butterflies, rely exclusively on milkweed plants as a food source for their larvae. These plants contain acrid milky juices that probably make the larvae and their subsequent stages distasteful to predators.