Minnesota Wildflowers


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Asclepias incarnata (Swamp Milkweed)

Plant Info
Also known as: Swamp Silkweed
Genus:Asclepias
Family:Apocynaceae (Dogbane)
Life cycle:perennial
Origin:native
Habitat:sun; wet fields, swamps, along shores
Bloom season:June - September
Plant height:1 to 4 feet
County distribution (click map to enlarge):Minnesota county distribution map
Spotted in Ramsey County at:

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Detailed Information

Flower: 5-petals flat

[photo of flowers] 2 to 3-inch convex flower clusters at the top of the plant. Flowers are ¼-inch across with a 5-parted crown with a curved horn sticking out of each of the 5 cylindrical hoods in the crown, arching over the short column in the center. 5 downward-curved petals flare out beneath. Flower color ranges from pink to magenta to red, the central column of the star-shaped crown is usually cream colored.

Leaves and stems: opposite simple

[photo of leaves] Leaves are up to 6 inches long and 1½ inches wide, hairless and toothless, tapering to a point at the tip on a short stalk; oppositely attached at the stem. Stems are mostly hairless but may have lines of fine hairs in the upper plant.

Fruit:

[photo of fruit] Slender pods about 4 inches long containing many flat, brown seeds, each with a fuzzy parachute attached. When the pod splits open the seeds are carried away by the wind.

Notes:

All Asclepias were formerly in family Asclepiadaceae but have been reassigned to Apocynaceae (Dogbane). Swamp milkweed can be easily distinguished from other milkweeds with pink flowers by its long narrow leaves. It grows easily in a home garden with average to moist soil—it is nearly exploding in my own back yard in heavy clay soil. Butterflies love it, and not just the Monarchs. Bees love it, too.

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More photos

Photos by K. Chayka taken at Vadnais/Snail Lake Regional Park, Ramsey County. Photos courtesy Peter M. Dziuk taken in a private garden in Anoka County.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Jeffrey in Minneapolis
on: 2010-05-21 10:28:47

I find this plant all over the mississippi especially near boom island. I never knew what it was. Thanks.

Posted by: Joe in Hennepin Co.
on: 2010-09-06 21:23:22

I noticed a faint, pleasant fragrance from the flowers when I found some blooming by the Mississippi River earlier in the summer.

Posted by: Peg in Maplewood
on: 2011-07-14 09:14:11

I live on Lake Gervais and there are several swamp milkweed plants starting to bloom. If I watch them closely could I harvest the seed pods and plant more along the shoreline?

Posted by: K. Chayka
on: 2011-07-14 10:53:25

Swamp milkweed should expand on its own, given the right conditions. Just spreading seed along the shore probably won't do much, as it is doing that naturally now. If you collect seed you might pot them up and replant once they germinate.

I have an explosion of it in my own back yard this year, in a highly disturbed area where it came up last year. Now it's too much, and needs some serious thinning. :)

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