Swamp Milkweed
Asclepias incarnata subsp. incarnata L.
The common swamp milkweed, found through most of the range and the only one usually seen in Florida. Nearly every swamp milkweed cultivar on sale descends from this subspecies.
How to tell it apart
Nearly hairless, or with a line of fine hairs down one side of the stem. Leaves are narrow and smooth, and the flowers are bright pink to white with a paler crown.
Compare with subsp. pulchra. Everything else about the plant, including how to grow it and what it is worth to monarchs, is on the swamp milkweed page.
Where it grows
Most common west of the Appalachians, with scattered populations in the Rocky Mountain and Intermountain states, notably along the Snake River in Idaho. Whether those western populations are relicts or introductions is an open question. It is rare in Arizona, Louisiana and Montana.
Distribution follows the Flora of North America treatment, United States only. Swamp Milkweed as a whole is recorded in 46 states.
Flowering
Swamp Milkweed blooms June to September, peaking in July and August. Plants reach 2.3 ft–4.9 ft.
References
The description, distribution and synonymy here follow Mark Fishbein’s treatment of Asclepias in Flora of North America vol. 14 (2023).
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). Swamp Milkweed (Asclepias incarnata subsp. incarnata). Retrieved DATE, from https://milkweedusa.com/species/swamp-milkweed/incarnata/
"Swamp Milkweed (Asclepias incarnata subsp. incarnata)." Milkweed USA, 2026, https://milkweedusa.com/species/swamp-milkweed/incarnata/. Accessed DATE.
Milkweed USA. "Swamp Milkweed (Asclepias incarnata subsp. incarnata)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/species/swamp-milkweed/incarnata/.
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title = {Swamp Milkweed (Asclepias incarnata subsp. incarnata)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/species/swamp-milkweed/incarnata/},
note = {Accessed DATE}
}