The single most important plant for monarch butterflies — caterpillars eat only milkweed leaves, and milky sap makes them toxic to predators.

Also called: Silkweed, Wild Cotton

Native status: Native

§ Quick facts

SizeHeight 60–180 cm (2–6 ft); flower clusters 5–10 cm
WeightN/A
LifespanPerennial — individual 20+ years
OrderApocynales
FamilyApocynaceae

§ Encyclopedia

Asclepias syriaca, commonly called common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed, is a species of flowering plant. It is native to southern Canada and much of the United States east of the Rocky Mountains, excluding the drier parts of the prairies. It is in the genus Asclepias, the milkweeds. It grows in sandy soils as well as other kinds of soils in sunny areas.

Source: Wikipedia — Asclepias syriaca Licensed under CC BY-SA 4.0

§ Identification

Field marks. Tall erect stems with broad opposite oval leaves; globular umbels of pink-purple flowers; spindle-shaped seed pods.

Similar species. Other milkweeds.

Voice. N/A

§ Diet & behavior

Diet. N/A — photosynthesis

Behavior. Spreads by rhizomes in clonal patches. Pollination complex.

§ Range

Eastern and central North America from Canada through the central US

§ Habitat

Old fields, prairies, roadsides, and disturbed open habitats

§ Threats

Loss to herbicide-tolerant agriculture, mowing of roadside populations, suburbanization.

§ Conservation status

According to the IUCN Red List, the common milkweed is currently classified as Least Concern.

§ What helps

Plant milkweed native to your region. Skip glyphosate at home. Advocate for milkweed-friendly roadside management.

Support our work More ways to help

§ Further reading

§ Sources cited

  • USDA Plants Database
  • Xerces Society
  • Monarch Joint Venture