Aquatic Milkweed
Asclepias perennis Walter
A small, soft, white-flowered milkweed of southern swamps and river floodplains that will grow in standing water and in shade, two things no other milkweed manages. Its seeds are unique in the genus: they have no silky floss.
Also called Swamp White Milkweed, Thin-leaved Milkweed.
- Height
- 1 ft–3 ft
- Spread
- 1 ft–2 ft
- Flowers
- white, pink
- Bloom
- May to September
- Light
- Part shade, Shade, Full sun
- Soil moisture
- Wet
- USDA zones
- 6–9
- Leaves
- Opposite, lanceolate
- Sap
- Milky latex
- Roots
- Fibrous, clump-forming and easy to move
- Stratification
- None needed
- Range
- 17 states
When it flowers
Aquatic Milkweed blooms May to September, peaking in June and July and August.
How to identify it
- Grows in genuinely wet ground, often with its feet in water.
- Small white flowers, sometimes pink-flushed, in delicate clusters.
- Thin, soft, pointed leaves; the whole plant is fine-textured.
- Seeds lack the parachute of silk found in every other milkweed.
Ecology and wildlife value
The key monarch host in southeastern floodplain forest and cypress swamp, and one of the few milkweeds that stays soft and edible through the humid southern summer.
Growing aquatic milkweed
Superb for rain gardens, pond edges and shaded wet spots in the Southeast. Needs no stratification: sow fresh seed and it germinates in days. Blooms the first year.
Seed needs no cold stratification and can be sown fresh. Fibrous, clump-forming and easy to move. See how to plant milkweed seed for the full method.
Cautions
Standard milkweed cautions. More on milkweed toxicity.
Where aquatic milkweed grows
Recorded in 17 states: Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Missouri, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia.
Distribution is generalized to state level. For county-level maps see USDA PLANTS and BONAP.
Frequently asked questions
What milkweed grows in Florida?
Aquatic milkweed (A. perennis) for wet and shaded sites, pinewoods milkweed (A. humistrata) and butterfly weed for dry sand, and swamp milkweed in the north of the state. Florida gardeners should avoid tropical milkweed, which breeds monarchs year-round and spreads OE parasites.
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 30270360-2. Royal Botanic Gardens, Kew. Accepted name, authorship and global distribution.
- GBIF 3170346. Global Biodiversity Information Facility. Aggregated occurrence records.
- iNaturalist 120152. 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
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Milkweed USA. (2026). Aquatic Milkweed (Asclepias perennis). Retrieved DATE, from https://milkweedusa.com/species/aquatic-milkweed/
"Aquatic Milkweed (Asclepias perennis)." Milkweed USA, 2026, https://milkweedusa.com/species/aquatic-milkweed/. Accessed DATE.
Milkweed USA. "Aquatic Milkweed (Asclepias perennis)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/species/aquatic-milkweed/.
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title = {Aquatic Milkweed (Asclepias perennis)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/species/aquatic-milkweed/},
note = {Accessed DATE}
}