Asclepias syriaca (also known as the common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed) is a species of milkweed plant. It belongs in the subfamily Asclepiadoideae. It is native to North America. It blooms from June to August. The flowers are green and purple. This species is found in prairies, meadows, and fields. Common Milkweed likes damp to dry soil and sunny or partly shaded places. It is about 0.5 to 1.5 meters in height (1½-5 feet).