Family:     Apocynaceae (Dogbane family)

Duration:  Perennial

Height:     up to 90 cm (up to 3 ft)

Blooming: June - August

 

Sullivant's Milkweed

Asclepias sullivantii Engelm. ex A. Gray

Stem: erect, stout, and smooth (hairless).  When broken, a milky sap comes out.  No branching.

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Flowers: relatively large, 5-parted flower that spreads from a common point in clusters and blooms throughout the summer. Its color is a pink to purplish cream. The flowers smell fragrant.  The horns do not exceed the hood but are turning inward.  Usually, a plant has one to three umbels of flowers.

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Leaves: simple, opposite leaves up to 15 cm (6 in) long and up to 7.5 cm (3 in) wide.  There is no hair on the underside of the leaves and they are usually sessile meaning that they are stalkless.  Many times the leaves are slightly wavy.

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Fruits: large follicles, which can be 10 cm (4 in) long, that are smooth or sometimes spiny which turn a grayish brown and split open releasing the brown seeds which are attached to white hairs called a "coma".

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Sun: Full

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Comments: Sullivant's milklweed is one of the showiest milkweeds in Northwest Indiana with the pink mid-veins and large flowers.  It looks very similar to the common milkweed (Asclepias syriaca); however Sullivant's has no hair on the stem or leaves, larger flowers, and usually smooth to bumpy fruits.  Common milkweed's fruits are very warty.

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Etymology: The genus Asclepias was named by Carl Linnaeus after the Greek god of medicine, Asclepius.  The name, sullivantii, is in tribute to the botanist and the legendary bryologist, William Starling Sullivant.  He wrote the leading botanists, Torrey and Gray, that he thought it was a new species, but neither of them thought so.  It wasn't until Engelmann described it that it was recognized as its own species.

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all photos by Nathanael Pilla

SOURCES & FURTHER RESOURCES:

Bonap map - Asclepias

Flora of Wisconsin - Asclepias sullivantii

Illinois Wildflowers - Prairie Milkweed

Michigan Flora - Asclepias sullivantii

Monarch Watch - Sullivant's milkweed

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Stuckey, R.L. and Roberts, M.L., 1991. Frontier botanist: William Starling Sullivant's flowering-plant botany of Ohio (1830-1850). BRIT Press.