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
Wetland Indicator Status:GP: FACW MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals Cluster type: 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: Leaf attachment: opposite Leaf type: 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: Fruit type: capsule/pod Fruit type: seed with plume

[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 - 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 - 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 - 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. :)

Posted by: Susan - Center City, Chisago County
on: 2012-07-31 08:50:07

This plant is blooming in two of my perennial flower beds. I left it because I didn't know what it was and was surprised when it bloomed with dusty pink flowers. There is a swamp behind my house and a lake in front.

Posted by: Alex - St paul MN
on: 2012-09-30 19:53:05

I have a bunch of theses plants from a "mother" plant I got at highland nurshery. Very beautiful fall color, but yes its invasive, although native. They shouldn't be pulled up as they are native.

Posted by: K. Chayka
on: 2012-09-30 20:22:57

Just because it's native, doesn't mean you have to let it run wild! Judicious pruning and thinning of overzealous plants is not a bad thing :-) I have swamp milkweed in my own yard so I know it can take over if you let it. I do check for Monarch butterfly eggs before I yank it up, though, as this is a great host plant.

Posted by: Tammy - Jordan (Scott County)
on: 2014-06-12 22:09:52

If you are looking to help the Monarchs, this is a great alternative to common milkweed for the suburban garden. They don't become weedy looking and spread mainly from seeds rather than underground roots. If they overcome your garden please share with your friends and neighbors. We can't waste a single milkweed plant!

Posted by: Alan - Maplewood
on: 2014-07-22 16:15:57

I found a white variant of this growing in a patch of the pink flowered swamp milkweed on the north side of Wakefield Lake in Maplewood today.

Posted by: Kathleen - Columbia Heights & Bigfork
on: 2014-08-05 14:58:42

I have a three year old large patch of swamp milkweed in the yard at Columbia Heights. Supposed to be good for the monarchs so I have left it. Need to get rid of it - only attracted flies this year! Seed heads are forming, will take it up North.

Posted by: K. Chayka
on: 2014-08-05 20:43:52

Kathleen, if I could only have 3 plants in my yard, swamp milkweed would be one of them. They are great for all kinds of pollinators, not just Monarchs. We always have a wide variety of bees, wasps, flies, beetles, and butterflies on ours. It does spread like crazy if you let it, but just remove the pods before they shed their seed and uproot the excess seedlings each year and it will stay in check.

Posted by: J.H. - Martin County
on: 2014-08-10 07:55:46

These grow in almost every ditch and field here, but they prefer moist ground, my niece calls them cinnamon plant, because that's what they smell like to her, they do smell good!.

Posted by: Kathleen - Columbia Heights & Bigfork
on: 2014-08-21 14:21:22

My mistake, my patch of milkweed is "common", not swamp. I am trying to establish the swamp. I took the common plants with their seed heads and distributed them on my property near Bigfork. Anybody know, do I need to dig out all roots to stop it in my yard? I have removed all seed pods before they open, but it has not slowed the growth. They do smell wonderful in bloom!

Posted by: K. Chayka
on: 2014-08-21 20:23:40

Kathleen, common milkweed spreads vegetatively by creeping rhizomes as well as by seed. Uproot excess plants and remove the pods to keep it in check.

Posted by: Rolfe - Falcon Heights, MN
on: 2015-05-06 16:33:08

Where can I purchase swamp milkweed plants -- in pots? Thanks.

Posted by: K. Chayka
on: 2015-05-06 22:44:53

Rolfe, see "where to buy native seed and plants" that's on almost every page of the website.

Posted by: Ann - Todd County
on: 2015-07-16 19:30:06

Even though Tod county is not highlighted on the map, I have found this plant along the Sauk River, by Little Sauk.

Posted by: Miles B - Cottage Grove
on: 2016-01-29 15:51:46

My wife and I just received a couple packages of seed from our employer, Andersen Windows. They have signed the Pollinator Pledge to improve habitat along the St Croix corridor. While we live in southern Cottage Grove, we do have a lot of pollinating creatures. I'm concerned about keeping it wet enough. We will see what happens, but with February on the horizon, it'll be awhile.

Posted by: eric - minneapolis
on: 2016-05-25 04:31:50

I will gladly pay anyone to harvest this plant and deliver it to me email me if interested. Thank you for your time

Posted by: K. Chayka
on: 2016-05-25 06:07:27

Eric, go buy some seed - it's readily available by mail order.

Posted by: Leanne - Goodhue County
on: 2016-05-28 16:58:33

Milkweed has popped up on our property largely in the past few years. We live in a farming community with our backyard meeting up to a gravel pit. The soil in our yard and the back hill into to the pit Is clay-based. The nearest lake is 15 miles away. They are starting to inhabit the raised garden we started 15 years ago. I use a spade to dig out the sprouts as they appear but have yet to get far enough down to find the start of the roots. I've dug as deep as 15" and still end up breaking the crisp white stem!

Posted by: Leah B - Big Willow Park, Minnetonka
on: 2017-07-21 09:12:55

I found one plant growing on the waters edge , near the path that runs parallel with Minnetonka blvd. I love discovering all the different varieties of milkweed. This one was brilliantly colored!

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