The genus Asclepias, commonly known as Milkweed, comprises more than 100 species, the best known of which are North American wildflowers. They have small, curiously shaped blooms that appear in clusters and are irresistable to butterflies. Milkweed is the host plant for Monarch butterflies - it is the only food source for Monarch caterpillars, and the butterflies will breed only where Milkweeds are found.
Asclepias tuberosa is native to eastern North America and is commonly referred to as Butterfly Weed. It blooms in June and July and makes a fine addition to a hot-colored border. It needs well-drained soil and full sun.