Asclepias is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic.
Common milkweed (Asclepias syriaca) is a native herbaceous perennial whose main virtue is its appeal to butterflies—especially the monarch, which deposits its eggs on the milkweed. When the caterpillars hatch, they feed on the leaves of milkweed. Common milkweed plants grow to about two to four feet in height, with a thin, vertical growth habit. The long, oblong leaves are light green and grow to about eight inches long. The stems and leaves bleed a milky sap when cut, which gives the plant its name. In late spring to mid-summer, fragrant clusters of pink-purple flowers appear. The flowers produce warty seed pods two to four inches long that split when ripe to cast many fine seeds to the wind.