Approximately 25 miles west of the Pony Express Conservation Area on the Missouri River is the original site of a settlement known as Blacksnake Hills, later to become the city of St.
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Scientific Name
Asclepias syriaca
Family
Apocynaceae (dogbanes); formerly Asclepiadaceae (milkweeds)
Description
Common milkweed is famous as a food plant for monarch butterflies. It bears curious seedpods bearing seeds that fly on silky parachutes. It's common statewide in a variety of habitats.
Common milkweed is a sturdy, upright, perennial plant with broad leaves and milky sap.
The flowers are pink to lilac, very fragrant, and borne in clusters both at the stem tips and along the stems, arising from the leaf axils.
Blooms May–August.
The leaves are broadly elliptical, rounded at the base, to 6 inches long, with fine hairs underneath, on distinct leaf stalks.
The fruits are large seedpods (technically follicles), elongated and covered with slender warty projections. When dry, these split to release hundreds of seeds, each attached to a “parachute” of white, silky, flossy hairs that can carry them on the wind.
Similar species: There are 17 species in the genus Asclepias in Missouri. The one most similar to common milkweed is purple milkweed, but its flowers are darker and more purplish, and its pods lack slender warty projections.
Learn more about Missouri's milkweeds on their group page and on the several other individual species pages in this guide.
Size
Height: usually to about 3–4 feet, but can grow to 6 feet.
Where To Find
Statewide.
Habitat and Conservation
Grows in upland fields, prairies, pastures, glades, roadsides, wasteland, edges of woods, and open, disturbed places.
True to its common name, this is the most commonly seen milkweed, especially in abandoned fields and waste places, where it is an early colonizer of disturbed soil.
Status
Native Missouri wildflower. Sometimes considered a weed. Increasingly appreciated and cultivated as a critical food plant for monarch butterflies.
Human Connections
Common milkweed has had many uses. In the past people have attempted to make rubber out of the sap’s latex. The flossy seed hairs have been used as a stuffing for bedding and for life preservers. The dried pods are used in crafts and flower arrangements. The stem fibers can be used as a source for cordage, similar to flax or hemp.
This and other milkweeds are growing in popularity among home gardeners, since they are the required food plants for monarch butterfly caterpillars. Adult monarchs lay eggs on milkweeds, and the caterpillars eat the foliage. Milkweeds are also a bonanza for a wide variety of insect pollinators, which become food for birds and other insectivores.
Native milkweeds are extremely important in conservation of the monarch butterfly, whose numbers have been plummeting. Strong herbicides, and the elimination of fence rows and other weedy places, have vastly reduced the number of milkweeds available for monarchs. You can help increase monarch numbers by growing native milkweeds.
Ecosystem Connections
This is an important food plant for monarch butterflies, whose caterpillars eat the bitter foliage and store its toxic sap in their bodies. This makes monarch butterflies unpalatable to would-be predators. The distinctive orange coloration of monarchs helps their predators to remember which type of insect made them feel ill. Many other, less famous insects eat milkweed and defend against predation the same way.
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Media Gallery
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Caption
Common milkweed is famous as a food plant for monarch butterflies. It bears curious seedpods bearing seeds that fly on silky parachutes. It's common statewide in a variety of habitats.
Credit
Julianna Schroeder
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Use of this image is restricted to MDC only
Image
Caption
True to its name, common milkweed is the most commonly seen milkweed, especially in abandoned fields and waste places, where it is an early colonizer of disturbed soil.
Credit
Julianna Schroeder
Right to Use
Use of this image is restricted to MDC only
Image
Caption
A wildflower common statewide, found in a variety of habitats, common milkweed is famous as a food plant for monarch butterflies. It is also notable for its curious seedpods bearing seeds that fly on silky parachutes.
Credit
MDC Staff
Right to Use
Photo by MDC Staff, courtesy Missouri Department of Conservation
Image
Caption
The seedpods of common milkweed are covered with slender warty projections. The pods of the similar-looking purple milkweed are smooth and lack these projections.
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Photo by MDC Staff, courtesy Missouri Department of Conservation
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Caption
Common milkweed is the most commonly seen milkweed because it is an early colonizer of disturbed soils.
Right to Use
Photo by MDC Staff, courtesy Missouri Department of Conservation
Image
Caption
When dry, the pods of common milkweed split open to release hundreds of seeds, each attached to a “parachute” of white, silky, flossy hairs that can carry them on the wind.
Credit
Julianna Schroeder
Right to Use
Use of this image is restricted to MDC only
Image
Caption
Common milkweed, Asclepias syriaca, blooms May–August. The flowers are borne in clusters both at the stem tips and along the stems, arising from the leaf axils.
Credit
Julianna Schroeder
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Use of this image is restricted to MDC only
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Caption
Common milkweed flower clusters amount to a mini habitat for visiting pollinators as well as the insects and spiders that lie in wait for them. Many additional insects feed on milkweed foliage, acquiring its toxic chemicals, which make them unpalatable for their predators.
Credit
Julianna Schroeder
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Use of this image is restricted to MDC only
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Milkweed flowers are unique. Above the sepals and petals, which flare away backward, are 5 petal-like hoods and 5 pronglike horns. At the center is a columnlike, 5-lobed structure that is a fusion of anthers and stigmas.
Credit
Julianna Schroeder
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Use of this image is restricted to MDC only
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Milkweeds’ unique flower structures and unusual pollination system prevent their flowers from self-fertilizing. The elaborate floral ecology explains why a milkweed plant creates many, many flowers but only produces a few pods.
Credit
Julianna Schroeder
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Use of this image is restricted to MDC only
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Among the many insects that feed on milkweeds and become toxic to their predators are monarch butterflies, milkweed tussock moths, milkweed longhorn beetles, large and small milkweed bugs, milkweed leaf beetles, and milkweed aphids.
Credit
Julianna Schroeder
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Use of this image is restricted to MDC only
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Credit
Noppadol Paothong
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Photo by Noppadol Paothong, courtesy Missouri Department of Conservation
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MDC
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Photo by MDC, courtesy Missouri Department of Conservation
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David Stonner
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Photo by David Stonner, courtesy Missouri Department of Conservation
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Similar Species
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Where to See Species
About Wildflowers, Grasses and Other Nonwoody Plants in Missouri
A very simple way of thinking about the green world is to divide the vascular plants into two groups: woody and nonwoody (or herbaceous). But this is an artificial division; many plant families include some species that are woody and some that are not. The diversity of nonwoody vascular plants is staggering! Think of all the ferns, grasses, sedges, lilies, peas, sunflowers, nightshades, milkweeds, mustards, mints, and mallows — weeds and wildflowers — and many more!