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Common milkweed

Botanical Name:

Asclepias syriaca

Common Name:

Common milkweed,Common Silkweed,Milkweed,Silk Grass,Silky Swallow Wort,Virginian Silk,Seidenp Flanze,Algodoncilla


The Common Milkweed is the plant that most people associate with the word “milkweed”. This is a tall and conspicuous species that sometimes forms large clones. The umbels bear large balls of pink to purplish flowers that have an attractive odor. This species is known to form hybrids with both A. exaltata (in the east) and A. speciosa (in the west). Follicles split open in the fall and early winter dispensing wind borne seeds. Among the milkweeds, this species is the best at colonizing in disturbed sites. Within its range it can be found in a broad array of habitats from croplands, to pastures, roadsides, ditches and old fields. It is surprisingly rare in prairies in the Midwest being found mostly in disturbed sites within these habitats. As an indigenous species of the southern Great Plains, it has all the attributes of what some ecologists call a “fugitive species”. That is, one whose appearance and persistence is dependent on disturbance due to its inability to compete with other vegetation. In the northern parts of its range it seems to be a more permanent member of the floral communities. This plant differs from Showy Milkweed (A. speciosa) in having an unbranched stem. The plant contains cardiac glycosides, allied to digitalins used in treating some heart disease. These glycosides, when absorbed by monarch butterfly larvae whose sole source of food is milkweed foliage, make the larvae and adult butterflies toxic to birds and other predators.

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Bloom Time

Late spring or early summer, Summer, Jun, Jul, Aug

Plant Type

Perennials, Herb/Forb, Herbaceous Perennial, Native Plant, Poisonous, Wildflower, Herb



Plant Height

3-6 ft.


2- to 3-in., domed umbel of dusty pink or lavender 5 petaled flowers with up to 100 flowers per cluster and 1-3 clusters per stem. They grow in the leaf axis; often drooping. The bloom season is long-lasting from June through August., Slightly pendulous spherical umbels with as many as 100 flowers per umbel, but usually 30+/- flowers. 3+/- umbels per stem. Pedicels are 1 1/2 in (4 cm) long. Petals up to 1/3 in (9mm) long. Hoods and horns are white or purple. Corolla reflexes backward to expose the hoods and horns. Horn protrudes through the hoods.


Fruit a hairy and spiked gray follicle dry and inflated, 2"-4" long 1 2/3" wide erect, with a thick end and tapered tip. It has many hair-tufted seeds that are wind dispersed. Seed pod has a warty appearance and is used in dried flower arrangments. Displays from July through September, Follicles approximately 3 ½ in (9 cm) long to 1 2/3 in (4 cm) at the widest point. Fruit color is grayish and is thick at the base and tapers down to a narrow tip. Follicles are covered with hair and soft spikes. Fruits split open between September-October.

How to Grow


Low, Average, Wet Mesic, Mesic, Dry Mesic, Dry


Full Sun, Full Sun to Partial Shade, Full sun (6 or more hours of direct sunlight a day), Sun


Medium to fine sandy, clayey, or rocky calcareous soils. Also found in well-drained loamy soils.






Specialized Bees


Poisonous parts include milky sap from leaves, stems. Toxic only in large quantities. Symptoms include vomiting, stupor, weakness, spasms by ingesting other species; need careful identification. Toxic Principle: Resinoid, cardiac glycoside in other species (Poisonous Plants of N.C. State).

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