swamp milkweed

(Asclepias incarnata ssp. incarnata)

Conservation Status
swamp milkweed
  IUCN Red List

LC - Least Concern


N5 - Secure

SNR - Unranked


not listed

Wetland Indicator Status
  Great Plains

FACW - Facultative wetland


OBL - Obligate wetland

  Northcentral & Northeast

OBL - Obligate wetland


Swamp milkweed is an erect, perennial forb. One to several stems rise from a short, fibrous rhizome. It often grows in clumps. The leaves and stems contain a milky juice.

The stems are erect and usually repeatedly branched above the middle. They are usually hairless except for a vertical line of hairs on each side between the leaf nodes on the upper half.

The leaves are opposite, untoothed, 4 to 7 long, 1 to 2 wide, and lance-shaped or oblong. They gradually taper to a sharp point. They are attached to the stem on short leaf stalks. The lower surface is hairless.

The inflorescence is usually several large, dense, umbrella-shaped clusters (umbels) rising from the upper leaf axils and at the end of the stem. The clusters are 3 to 4 in diameter and erect on a hairy, 2 long stalk. They typically have 20 to 30 flowers.

The structure of the typical milkweed flower is unique and instantly recognizable. There are 5 petals bent backward at the base and hanging downward. Subtending the petals are 5 much shorter, light green, lance-shaped sepals. There are 5 stamens. Formed from the filament of each stamen is a petal-like appendage. The appendage consists of a tubular hood surrounding an awl-shaped horn in the center of the hood. The stamens and the stigma are fused together into a crown-like structure (gynostegium). Each stigma has a long slit designed to catch the legs of a pollinating insect. A small, dark, sticky gland above this slit is attached to pollen sacs from adjacent anthers. These glands are designed to break off as an insect pulls its leg free of the slit, and remain attached to the insects leg. The flowers are pollinated by larger insects strong enough to lift off with the pollen sacs attached. Smaller insects are caught in a death trap or leave behind their detached legs.

The flowers of this plant are shaped like the typical milkweed flower and are fragrant. They are tall and ¼ wide. The petals are pink to red. They bend backward at the base, hang downward, then curl upward near the tip. They are separated from the hoods by a distinct column. The horns are much taller than the hoods. They project from the hoods and are curved inwards.

The fruit is a narrow, spindle-shaped pod. It is 3 to 5 long and hairless. It is held erect on an erect stalk. It opens on one side exposing the seeds to spreading by the wind. The seeds have a tuft of silvery-white, silky hairs at the tip.




2 to 5


Flower Color


Pink or red


Similar Species


Common milkweed (Asclepias syriaca)stems are unbranched and hairy. The upper surface of the leaves are softly hairy. The umbels have 20 to 130 flowers. The horns are shorter than the hoods. The fruits are fat and are covered with warts.

Purple milkweed (Asclepias purpurascens) stems are unbranched and are covered with short, fine, soft hairs. The leaves are wider, elliptical or oblong, and downy on the underside. The umbels have up to 50 flowers. The horns are much shorter than the hoods.


Wet to moist. Open swamps, marshes, streambanks, ditches, wet prairies, wet fields, meadows. Full sun.




June to August


Faunal Associations


Milkweeds are the only plants that Monarchs lay their eggs on. The eggs are laid on the underside of healthy young leaves.




This and other milkweeds contain cardiac glycosides and may be poisonous to both humans and livestock.


Pests and Diseases






Distribution Map



2, 3, 4, 5, 7, 28, 29, 30.









  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Asteranae  


Gentianales (gentians, dogbanes, madders, and allies)  


Apocynaceae (dogbane)  
  Subfamily Asclepiadoideae (milkweeds)  
  Tribe Asclepiadeae  
  Subtribe Asclepiadinae  
  Genus Asclepias (milkweeds)  


Asclepias incarnata (swamp milkweed)  

Subordinate Taxa






Asclepias incarnata var. incarnata


Common Names


marsh milkweed

rose milkweed

swamp milkweed













The upper angle where the leaf stalk meets the stem.



A crown-like structure of plants of the genus Asclepias formed by the fusion of the anthers with the stigmas.



Long, straight, and narrow, with more or less parallel sides, like a blade of grass.



A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.



A flat-topped or convex, umbrella-shaped cluster of flowers or buds arising from more or less a single point.

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    swamp milkweed      

Wayne Rasmussen


Monarch on swamp milkweed

    monarch   monarch  
MinnesotaSeasons.com Photos


    swamp milkweed   swamp milkweed  
    swamp milkweed      


    swamp milkweed      


    swamp milkweed   swamp milkweed  


    swamp milkweed   swamp milkweed  
    swamp milkweed      


    swamp milkweed      


    swamp milkweed   swamp milkweed  


    swamp milkweed   swamp milkweed  
    swamp milkweed   swamp milkweed  


    swamp milkweed   swamp milkweed  



  Swamp Milkweed (Asclepias incarnata)
Andree Reno Sanborn
  Swamp Milkweed (Asclepias incarnata)  
  Asclepias incarnata SWAMP MILKWEED
Frank Mayfield
  Asclepias incarnata SWAMP MILKWEED  
  A. incarnata
Joshua Mayer
  A. incarnata  

Swamp Milkweed




Visitor Videos

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Other Videos
  Minnesota Native Plant - Swamp Milkweed (Asclepias Incarnata)

Published on Jul 15, 2013

Swamp Milkweed is the focus of this Minnesota Native Plant video. Common to swamps, streams and ponds around Minnesota, it's a beautiful plant for the native garden.

  Swamp Milkweed - Asclepias incarnata blooming at Ion Exchange

Uploaded on Aug 1, 2011

Earthyman views Swamp Milkweed (Asclepias incarnata) in full bloom at Ion Exchange in Northeast Iowa. http://www.ionxchange.com

  Swamp Milkweed
Chicagoland Gardening

Uploaded on Aug 7, 2008

Chicagoland Gardening Magazine editor Carolyn Ulrich discusses swamp milkweed, a native prairie plant.

Swamp Milkweed

Uploaded on Jul 29, 2011

What I believe to be Asclepias incarnata, Swamp Milkweed, growing out in a wetland field. I've never seen this species grow as a single stem before.

  Monarch larva eating Swamp Milkweed

Uploaded on Feb 2, 2011




Visitor Sightings

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Location: Lake Shore, Cass County

swamp milkweed  
  Wayne Rasmussen

Location: Joy Park

  Wayne Rasmussen

Location: Joy Park

MinnesotaSeasons.com Sightings

Anna Gronseth Prairie

Antelope Valley SNA

Avon Hills Forest SNA, North Unit

Bertram Chain of Lakes Regional Park

Blaine Preserve SNA

Blue Mounds State Park

Carver Park Reserve

Cedar Rock SNA

Charles A. Lindbergh State Park

Chippewa Prairie

Clifton E. French Regional Park

Crosby Farm Regional Park

Crow Wing State Park

Des Moines River SNA

Felton WMA

Foxhome Prairie

Frontenac State Park

Glacial Lakes State Park

Glendalough State Park

Glynn Prairie SNA

Greenleaf Lake SRA

Hole-in-the-Mountain Prairie

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Iron Springs Bog SNA

Joseph A. Tauer Prairie SNA

Kettledrummer Prairie

Kilen Woods State Park

Lake Alexander Woods SNA, South Unit

Lake Louise State Park

Lake Rebecca Park Reserve

Langhei Prairie SNA

Lebanon Hills Regional Park

Leif Mountain

Lester Lake SNA

Maplewood State Park

Margherita Preserve-Audubon Prairie

Mille Lacs Moraine SNA

Miller Prairie, West Unit

Minnesota Valley NWR, Long Meadow Lake Unit

Minnesota Valley NWR, Louisville Swamp Unit

Mississippi River County Park

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Mound Spring Prairie SNA, North Unit

Murphy-Hanrehan Park Reserve

Northern Tallgrass Prairie NWR, Hoffman Unit

Northern Tallgrass Prairie NWR, Touch the Sky Prairie Unit

Otter Tail Prairie SNA

P.N. and G.M. Nelson Wildlife Sanctuary

Pembina Trail Preserve SNA, Crookston Prairie Unit

Pembina Trail Preserve SNA, Pembina Trail Unit

Phelps Lake WMA

Pilot Knob

Pin Oak Prairie SNA

Plover Prairie, East Unit

Prairie Coteau SNA

Racine Prairie SNA

Regal Meadow

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Rice Lake State Park

Richard M. & Mathilde Rice Elliott SNA

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St. Croix State Park

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Savage Fen SNA

Savanna Portage State Park

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Split Rock Creek State Park

Spring Prairie Preserve

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Twin Valley Prairie Addition

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Uncas Dunes SNA

Verlyn Marth Memorial Prairie SNA

Vermillion River WMA

Western Prairie SNA

Whitetail Woods Regional Park

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Zimmerman Prairie







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