Asclepias syriaca

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Common Milkweed
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Gentianales
Family:	Apocynaceae
Subfamily:	Asclepiadoideae
Genus:	Asclepias
Species:	A. syriaca
Binomial name
Asclepias syriaca L.

Asclepias syriaca, commonly called Common Milkweed, Butterfly flower, Silkweed, Silky Swallow-wort, Virginia Silkweed, is a herbaceous plant species. It is in the genus Asclepias, making it a type of milkweed. This species is native to most of North America east of the Rocky Mountains, excluding 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 to 1-2 m tall from a rhizome. The stem 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.

Uses

The plant's latex contains large quantities of glycosides, making the leaves and seed pods toxic for sheep and other large mammals, and potentially humans (though large quantities of the foul-tasting parts would need to be eaten). The young shoots, young leaves, flower buds and immature fruits are all edible, however it is important to make sure that they are thoroughly and completely cooked before eating them; otherwise they are still toxic. It is important not to confuse young shoots with those of the toxic Spreading Dogbane and Common Dogbane.

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 and it has been found to be hypoallergenic. The fluffy seed hairs have been used as the traditional background for mounted butterflies. The compressed floss has a beautiful silk-like sheen. The plant has also 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. Milkweed oil from the seeds can be easily converted into cinamic acid which is a very potent sunscreen when used at a 1-5% concentration.

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), Large Milkweed Bug (Oncopeltus fasciatus), Small Milkweed Bug (Lygaeus kalmii) and Milkweed Leaf Beetle (Labidomera clivicollis). The flower nectar has a high glucose content and was used by natives as a sweetener.

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.

Gallery

Top of the plant showing an umbel in flower	Forming umbels	Unopened flowers in umbel	Close-up of flowers
Fruits releasing seeds		Close-up of seeds

References

• Common Milkweed page from the Natural Resources Conservation Service Plants Database
• Lamoureux, Gisèle and al (1978). Plantes sauvages des villes et des champs. Fleurbec/Éditeur officiel du Québec. ISBN 2-920174-00-2. 
• Lamoureux, Gisèle and al (1981). Plantes sauvages comestibles. Fleurbec. ISBN 2-920174-03-7. 
• Brother Marie-Victorin (1975). Flore Laurentienne. Les Presses de l'Université de Montréal. ISBN 0-8405-0018-1. 
• Buchanan, Rita (1987). A Weaver's Garden. Interweave Press, Inc. ISBN 0-934026-26-9. 

External links

• Media related to Asclepias syriaca at Wikimedia Commons