Common Milkweed (Butterfly flower, Silkweed, Silky Swallow-wort, Virginia Silkweed;Asclepias syriaca) is a species of milkweed, native to most of North America east of the Rocky Mountains, with the exception of the drier parts of the Prairies. It grows in sandy soils and appreciates lots of sunlight. It was one of the earliest North American species described in Cornut's 1635 Canadensium plantarum historia. The specific epithet was reused by Linnaeus due to Cornut's confusion with a species from Asia Minor.
Common milkweed is a herbaceous perennial plant growing from a rhizome to 1-2 m tall. The stem is very hairy, and all parts of the plants produce a white latex when broken. The leaves are opposite, simple broad ovate-lanceolate, 7-25 cm long and 3-12 cm broad, usually with an undulate margin and a red-colored main vein. They have a very short petiole and a velvety underside.
The flowers are grouped in several spherical umbels with numerous flowers in each umbel. The individual flowers are small, 1-2 cm diameter, perfumed, with five cornate hoods. The seeds are attached to long, white flossy hairs and encased in large follicles.
Failed attempts have been made to exploit rubber (from the latex) and fiber (from the seed's floss) production from the plant industrially. The floss was nonetheless used for stuffing. However, the plant has been explored for commercial use of its bast (inner bark) fiber which is both strong and soft. U.S. Department of Agriculture studies in the 1890s and 1940s found that Milkweed has more potential for commercial processing than any other indigenous bast fiber plant, with estimated yields as high as hemp and quality as good as flax. Both the bast fiber and the floss were used historically by Native Americans for cordage and textiles.
The flowers often constitute small traps for insects who cannot take off again. Several insects live off the plant, including the Monarch Butterfly (Danaus plexippus), the Milkweed Beetle (Tetraopes tetraophtalmus), Small Milkweed Bug (Lygaeus kalmii) and Milkweed Leaf Beetle (Labidomera clivicollis).
Deforestation due to European settlement may have expanded the range and density of milkweed. The plant can become invasive and often acts as a weed. It is naturalized in several areas outside of its native range, including Oregon and parts of Europe.