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Asclepias L.

Kingdom: Plantae Rank: Genus Parent: Asclepiadaceae Status: Valid

Common Names:

  • MILKWEED - English, United States of America
  • SILKWEED - English, United States of America

Morphological Description

Diagnosis: Perennial herbs; stems erect to reclining; leaves alternate, opposite, or whorled, sessile or petioled; flowers in terminal or lateral umbels; corollas becoming reflexed or shallowly campanulate; hoods with or without an exserted appendage (= horn).


Ecology: Many species are poisonous in nature.

Notes: A genus of 100 species of the Americas, especially the United States; some are cultivated as ornamentals; others have been used medicinally since early times. Many if not most species are poisonous; however, all species are distasteful to livestock and severe losses usually occur only when animals are forced to eat the plants. Abundant MILKWEEDS in a pasture are often a sign of severe overgrazing. The poisonous principles include resinoids, cardiac glycosides, and alkaloids; the milky latex can cause dermatitis in susceptible individuals (Kingsbury 1964; Lewis & Elvin-Lewis 1977; Turner & Szczawinski 1991). Monarch butterflies (Danaus plexippus) feed as larvae on Asclepias species and obtain cardiac glycosides which provide them with protection from bird predators; the butterflies are poisonous only if they fed on poisonous plants as larvae (Scott 1986). The long silky hairs on the seeds were formerly used in making candle wicks (Ajilvsgi 1984). (Named from Greek Asklepios, god of medicine, alluding to its medicinal properties)