Prairie Milkweed
Asclepias sullivantii Engelm. ex A. Gray
Common milkweed’s refined cousin: the same big pink umbels and broad leaves, but smooth and hairless throughout, with an elegant red midrib and none of the coarseness. A tallgrass prairie plant that has declined sharply with the prairie itself.
Also called Sullivant’s Milkweed, Smooth Milkweed.
- Height
- 2 ft–4 ft
- Spread
- 1.5 ft–3 ft
- Flowers
- pink, rose
- Bloom
- June to July
- Light
- Full sun
- Soil moisture
- Average, Wet
- USDA zones
- 3–7
- Leaves
- Opposite, oblong
- Sap
- Milky latex
- Roots
- Rhizomatous, spreads by root
- Stratification
- 30 days cold-moist
- Range
- 14 states
When it flowers
Prairie Milkweed blooms June to July, peaking in June and July.
How to identify it
- Completely smooth and hairless, with no down on stems, leaves or pods.
- Leaf midrib is often flushed pink or red.
- Leaves have a small abrupt point at the tip and are held stiffly upright.
- Pods are smooth with only a few short blunt projections, unlike the warty pods of common milkweed.
Unfamiliar words are in the glossary, and the identification key will narrow a plant down from what you can see.
Ecology and wildlife value
A high-value monarch host with broad, soft leaves, now uncommon because it grows on exactly the deep moist prairie soils that were converted to row crops. Conservation-listed in several states.
Monarchs are not the only thing that will find it. Expect large milkweed bugs on ripening pods, oleander aphids on the stems, red milkweed beetles at the flowers and, in late summer, milkweed tussock moths. The flowers are a heavy nectar source, so bumble bees and large wasps work them hard, and they are the ones that actually move the pollen. Everything that lives on milkweed.
Growing prairie milkweed
A far better garden plant than common milkweed: similar looks, much slower spread. Prefers heavier, moister soil. Seed and plants are increasingly available from prairie nurseries.
Seed needs about 30 days of cold-moist stratification. Rhizomatous, spreads by root. See how to plant milkweed seed for the full method.
Cautions
Standard milkweed cautions. More on milkweed toxicity.
Where prairie milkweed grows
Recorded in 14 states: Iowa, Illinois, Indiana, Kansas, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Nebraska, Ohio, Oklahoma, South Dakota, Wisconsin.
County records from USDA PLANTS, public domain. Cross-check against BONAP and your regional flora before making management decisions.
Frequently asked questions
How is prairie milkweed different from common milkweed?
Prairie milkweed is completely hairless, has a reddish leaf midrib and nearly smooth pods, and spreads far less aggressively. Common milkweed is downy throughout with warty, spiny pods.
References and further reading
Names, ranges and conservation status here are drawn from the databases below. Where those disagree with a regional flora, trust the flora.
- Plants of the World Online 94678-1. Royal Botanic Gardens, Kew. Accepted name, authorship and global distribution.
- GBIF 3170265. Global Biodiversity Information Facility. Aggregated occurrence records.
- iNaturalist 158761. Community observations, photographs and phenology.
- Wikipedia. General-audience article on this species.
- BONAP county distribution map. Biota of North America Program. County-level range map.
- NatureServe Explorer. Conservation status ranks at global and state level.
- World Flora Online. Nomenclature and synonymy.
- Woodson, R. E. (1954). The North American species of Asclepias L.. Annals of the Missouri Botanical Garden 41(1): 1–211. The monograph the modern taxonomy of the genus still rests on. View
- Flora of North America Editorial Committee (eds.) (2026). Flora of North America North of Mexico. Oxford University Press, New York and Oxford. Accepted names, keys and descriptions for the North American flora. View
- Royal Botanic Gardens, Kew (2026). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Nomenclature and global distribution, keyed to IPNI name identifiers. View
- Kartesz, J. T. (Biota of North America Program) (2026). North American Plant Atlas. BONAP, Chapel Hill, North Carolina. County-level distribution maps, the basis for the ranges generalized here. View
- USDA, NRCS (2026). The PLANTS Database. National Plant Data Team, Greensboro, North Carolina. State-level distribution, wetland status and nomenclature. View
- Agrawal, A. A. (2017). Monarchs and Milkweed: A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution. Princeton University Press. The standard general account of the milkweed and monarch relationship. View
Cite this page
This page is licensed CC BY 4.0. Quote it, adapt it and reuse it, including commercially, as long as you credit Milkweed USA and link back.
Milkweed USA. (2026). Prairie Milkweed (Asclepias sullivantii). Retrieved DATE, from https://milkweedusa.com/species/prairie-milkweed/
"Prairie Milkweed (Asclepias sullivantii)." Milkweed USA, 2026, https://milkweedusa.com/species/prairie-milkweed/. Accessed DATE.
Milkweed USA. "Prairie Milkweed (Asclepias sullivantii)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/species/prairie-milkweed/.
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title = {Prairie Milkweed (Asclepias sullivantii)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/species/prairie-milkweed/},
note = {Accessed DATE}
}