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Asclepias syriaca

Asclepias syriaca, commonly called common milkweed, is a perennial flowering plant in the milkweed genus Asclepias.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 27, 2026|2 min read| Fact-checked

Asclepias syriaca, commonly called common milkweed, is a perennial flowering plant in the milkweed genus Asclepias. It is native to southern Canada and much of eastern North America, and it is notable as an important host plant for monarch butterflies. The plant produces milky sap, pink to purple flowers, and seed pods with silky-tufted seeds.

Description

Asclepias syriaca is a stout perennial herb with opposite leaves, hollow stems, and dense clusters of pink to purple flowers. Its fruit are large pods that release many flat seeds attached to silky hairs.

Distribution and habitat

The species is native to southern Canada and a broad portion of the eastern United States. It grows in sunny, open habitats such as fields, meadows, roadsides, pastures, and disturbed ground.

Ecology

Common milkweed provides nectar for pollinators and is widely recognized as a host plant for monarch butterfly larvae. Its milky sap and cardenolides are characteristic of milkweeds and can deter many herbivores.

Taxonomy and naming

The species was named by Carl Linnaeus, and the epithet syriaca reflects a historical error that linked the plant to Syria. It belongs to the milkweed genus Asclepias in the dogbane family, Apocynaceae.

Key facts

  • It is a herbaceous perennial that spreads by seed and underground rhizomes.
  • The plant exudes milky sap when damaged, a typical trait of milkweeds.
  • Flowers are usually pink to purple and appear in dense clusters.
  • It is an important larval host plant for monarch butterflies.
  • The species is native to southern Canada and much of eastern North America.
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Canadian context

Common milkweed is native to southern Canada and occurs in several provinces, where it is part of prairie, meadow, and roadside ecosystems. It is also of interest to Canadian conservation and gardening audiences because of its role in supporting monarch butterflies.

Frequently asked questions

What is Asclepias syriaca?
It is a species of milkweed commonly known as common milkweed, a perennial flowering plant native to eastern North America.
Why is it called common milkweed?
It is called milkweed because it produces milky sap when damaged, and “common” because it is one of the most widespread milkweed species in its range.
Is Asclepias syriaca important for monarch butterflies?
Yes. It is one of the most important host plants for monarch butterfly caterpillars.
Where does common milkweed grow?
It grows in sunny, open habitats such as fields, meadows, roadsides, pastures, and disturbed soils.
Is common milkweed native to Canada?
Yes. It is native to southern Canada, including parts of several provinces.
Why is the species name syriaca?
The name was based on Linnaeus’s mistaken belief that the plant came from Syria.

References

  1. Wikipedia — https://en.wikipedia.org/wiki/Asclepias_syriaca
    Supports: Common name, native range, general description
  2. Iowa State University Extension — https://crops.extension.iastate.edu/encyclopedia/common-milkweed
    Supports: Family, life cycle, habitat, plant description, milky sap
  3. USDA Forest Service — https://www.fs.usda.gov/wildflowers/plant-of-the-week/asclepias_syriaca.shtml
    Supports: Meaning of syriaca, distribution, native range, common name
  4. Flora of North America — https://floranorthamerica.org/Asclepias_syriaca
    Supports: Phenology, habitat, geographic distribution, ecological importance
  5. Missouri Botanical Garden — https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b480
    Supports: Growth habit, habitat, flowers, monarch butterfly host plant
  6. GBIF — https://www.gbif.org/species/144106379
    Supports: Taxonomy, family placement, genus information