Asclepias syriaca (Common Milkweed): Minnesota Wildflowers

Asclepias syriaca (Common Milkweed)

Plant Info
Also known as:	Silkweed, Milkplant
Genus:	Asclepias
Family:	Apocynaceae (Dogbane)
Life cycle:	perennial
Origin:	native
Habitat:	part shade, sun; wet or dry fields, along shores, edges of woods
Bloom season:	June - August
Plant height:	2 to 5 feet
MN county distribution (click map to enlarge):
National distribution (click map to enlarge):

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Detailed Information

Flower:

2-inch round clusters arising from leaf axils in the upper plant. Individual flowers are ½ inch across with a 5-parted crown and 5 downward-curved petals. Flower color ranges from dull pale pink to deep mauve, the tips of the star-shaped crown often cream colored.

Leaves and stems:

Leaves are up to 8 inches long and 3 inches wide, generally oval to oblong with a point at the tip and a short stalk, oppositely attached, toothless and softly hairy on the underside. The prominent midrib is creamy white to pink; the side veins on the leaf surface are all connected and do not extend to the edge of the leaf, creating a border effect all around the edge. Stems are hairy to varying degrees and unbranched.

Fruit:

Bumpy green pods about 5 inches long containing many flat, brown seeds, each with a papery wrapping and fuzzy parachute attached.

Seeds are arranged in layers like fish scales. When the pod splits open the seeds separate and are carried away by the wind.

Notes:

All Asclepias were formerly in family Asclepiadaceae but have been reassigned to Apocynaceae (Dogbane). Common Milkweed can be weedy, producing many offspring and crowding out other plants. This made it a noxious weed (i.e. agricultural pest) in some MN counties. One or two volunteered in my own back yard a few years. The next year a dozen more were sprouting up. I've since yanked it out and have Swamp Milkweed (Aslepias incarnata) taking its place, and lots of Monarch caterpillars calling my back yard home.

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More photos

Photos by K. Chayka taken in Ramsey County. Photos courtesy Peter M. Dziuk taken along Highway 61 just north of Duluth, and in Anoka County.

Comments

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

Posted by: Diana in Minneapolis
on: 2010-09-27 22:04:41

Is this a noxious weed because it takes over? I thought I should keep it in my front yard in NE Mpls for the Monarchs, but I kept taking it out because it crawled everywhere. (I also had aesclepius tuberosa - much more mild mannered.) In the end, I moved. It's still there.

Posted by: K. Chayka
on: 2010-10-01 09:52:32

LOL, did you move to get away from it? :-)

Yes, common milkweed can be a pretty prolific breeder and I believe it is an agricultural pest plant in some areas. I have some in my back yard now that started out as 1 plant a few years ago (seed dropped there by some critter, I imagine) and now it's over a dozen plants and spreading. Time for me to take some action myself so it doesn't crowd out the other natives growing in that corner.

Posted by: Paul O.
on: 2010-11-04 14:40:17

Please take the time to smell the milkweed. A warm, humid early morning in August is best. Marsh milkweed is even better. I have put amazement in the hearts of many by having them take a sniff. And they thought it was just a weed!

Posted by: Sonia in NE Minneapolis
on: 2011-05-31 11:32:27

Personally, I let this plant grow where it wants in my low-maintenance forest floor garden in NE Minneapolis. It is an attractive plant (in my opinion) and easy enough to pull when young if it's popping up somewhere it's not welcome. I don't find it too invasive. I encourage people to let at least a few plants grow in their yards so the monarch butterflies have a place to lay their eggs. It's such a delight when you notice a little yellow-striped caterpillar has taken up residence on your milkweed plant! Up North at my cabin they started mowing the ditches along the roadsides and completely eradicated the milkweed that grew in those limited sunny areas. I've since noticed I see far less monarchs up there around the lake, when they used to be plentiful.

Posted by: Desdamona in Roseville
on: 2011-07-02 12:02:21

I had this in my garden last summer, I pulled it out and got attacked by bees. This summer I have no Milkweed, no bees, and no butterflies. I guess this is what I deserve. Now I'm picking some patches to allow and plant native. Maybe nature will forgive me and come back to grace my vegetable garden. :-)

Posted by: Libby in Mound
on: 2011-07-13 21:21:18

I HAVE MILKWEED IN MY PRAIRIE GARDEN IN MOUND, MN. I CULTIVATE IT. I'VE READ THAT IT HAS MEDICINAL VALUE. ANYONE KNOW ABOUT THIS?

Posted by: Jill in Itasca County, Highway 1 east of Effie at entrance to Bass L
on: 2011-08-09 12:08:52

We have it here, even if it's not on the county list from USDA!

Posted by: artem in Isanti
on: 2012-06-22 19:37:46

I have about 6 acrs of this plant in my back yard bee's love it. Smells good! I will let it spread for my honey bees.

Posted by: Theresa in Duluth
on: 2012-08-23 15:41:12

I have a patch of this growing in a gravelly area of my yard. I've tried transplanting it to other areas but it doesn't do well in the clay soils. On the good side, I counted 23 monarch caterpillers and dozens of butterflies of several species on it just after the flood.