Summary ⁸

Asclepias incarnata, the swamp milkweed, rose milkweed, rose milkflower, swamp silkweed, or white Indian hemp, is a herbaceous perennial plant species native to North America. It grows in damp to wet soils and also is cultivated as a garden plant for its flowers, which attract butterflies and other pollinators with nectar. Like most other milkweeds, it has sap containing toxic chemicals, a characteristic that repels insects and other herbivorous an

Description ⁸

Swamp milkweed is an upright, 100 to 150 cm (39 to 59 in) tall plant, growing from thick, fleshy, white roots. Typically, its stems are branched and the clump forming plants emerge in late spring after most other plants have begun growth for the year. The oppositely arranged leaves are 7.5 to 15 cm (3 to 6 in) long and 1 to 4 cm (0.4 to 1.6 in) wide and are narrow and lance-shaped, with the ends tapering to a sharp point.

The plants bloom in early through mid-summer, producing small, fragrant, pink to mauve (sometimes white) colored flowers in rounded umbellate racemes. After blooming, green follicles, approximately 12 cm (4.7 in) long, are produced. When ripe, these pods split open releasing light to dark brown, flat seeds that are attached to silver-white, silky hairs which catch the wind. This natural mechanism for seed dispersal is similar to that used by other milkweed species.

Similar Species ⁹

Swamp milkweed is easily mistaken for the closely related and much more plentiful common milkweed. Swamp milkweed is a smaller, more slender plant overall, with smaller seedpods and narrower leaves.

Wildlife Interactions ⁹

Milkweeds are a required host plant for the monarch butterfly and many other species like milkweed bugs, milkweed beetles, and milkweed tussock moths. They provide ample nectar for bees, wasps, beetles, butterflies and moths. Because of their popularity among insects, milkweeds also serve as important hunting grounds for predators like spiders and praying mantids.

Habitat ⁸

Swamp milkweed prefers moisture retentive through damp soils in full sun or partial shade and is typically found growing wild near the edges of ponds, lakes, streams, and low areas—or along ditches. It is one of the best attractors of the monarch butterfly, which feeds on the flowers and lays her eggs on the plants. The emerging caterpillars feed on the leaves.

The plants have specialized roots which function in heavy, wet soils. The scented, thick, white roots are in environments low in oxygen. Blooming occurs in mid- through late summer and after blooming long, relatively thin, rounded follicles are produced that grow uprightly. They split open in late summer through late fall, releasing seeds attached to silky hairs, which act as parachutes that carry the seeds in wind currents.

Read More ¹⁰

• https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=g410
• https://www.wildflower.org/plants/result.php?id_plant=ASIN
• http://www.illinoiswildflowers.info/wetland/plants/sw_milkweed.htm

Sources and Credits

1. (c) Anita Gould, some rights reserved (CC BY-NC), uploaded by Anita Gould, http://www.flickr.com/photos/anitagould/30648177/
2. (c) aarongunnar, some rights reserved (CC BY), uploaded by aarongunnar
3. (c) yakfur, some rights reserved (CC BY-NC), uploaded by yakfur
4. (c) John, some rights reserved (CC BY-NC-SA), uploaded by John
5. (c) Ashley M Bradford, some rights reserved (CC BY-NC), uploaded by Ashley M Bradford
6. (c) Lena Struwe, some rights reserved (CC BY-SA), uploaded by Lena Struwe
7. anonymous, no known copyright restrictions (public domain), http://commons.wikimedia.org/wiki/File:Ascelpias_incarnata_seed.jpg
8. Adapted by Murfreesboro,TN, Natural Resource Division from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Asclepias_incarnata
9. Adapted by Murfreesboro,TN, Natural Resource Division from a work by (c) The Preserve at Shaker Village, some rights reserved (CC BY-SA), https://www.inaturalist.org/guide_taxa/523523
10. (c) Murfreesboro,TN, Natural Resource Division, some rights reserved (CC BY-SA)

More Info

• iNat taxon page
• Biodiversity Heritage Library
• BOLD Systems BIN search
• eFloras.org
• Flora of North America (beta)
• Global Biodiversity Information Facility (GBIF)
• Go Botany
• HOSTS - a Database of the World's Lepidopteran Hostplants
• IPNI (with links to POWO, WFO, and BHL)
• Maryland Biodiversity Project
• NatureServe Explorer 2.0
• OregonFlora.org
• SEINet Symbiota portals
• Tropicos
• USDA PLANTS database
• VASCAN by Canadensys
• World Flora Online

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