Whorled Milkweed
Asclepias verticillata L.
A wiry, fine-textured milkweed that looks more like a horsetail than an Asclepias, with needle-thin leaves in whorls up a slim stem and small greenish-white flowers late in the season. It slips into thin, poor, dry ground where nothing else will grow.
Also called Eastern Whorled Milkweed, Horsetail Milkweed.
- Height
- 1 ft–2.5 ft
- Spread
- 9 in–1.5 ft
- Flowers
- white, green
- Bloom
- June to September
- Light
- Full sun
- Soil moisture
- Dry, Average
- USDA zones
- 3–9
- Leaves
- Whorled, threadlike
- Sap
- Milky latex
- Roots
- Rhizomatous, spreads by root
- Stratification
- 30 days cold-moist
- Range
- 42 states
When it flowers
Whorled Milkweed blooms June to September, peaking in July and August.
How to identify it
- Leaves are thread-fine, one to two millimeters wide, arranged in whorls of three to six around the stem.
- The whole plant is slender and grass-like until it flowers.
- Small white to greenish flowers in several small clusters along the upper stem.
- Blooms notably late, often the last milkweed still in flower.
Ecology and wildlife value
A favorite of small native bees and predatory wasps, and a reliable late host for monarch larvae after the big species have gone tough and seedy. Its thin leaves dry quickly, so caterpillars often need several plants.
Growing whorled milkweed
Thrives on drought, gravel, thin soil and neglect. It spreads by slender rhizomes and self-sows freely, so treat it as a filler in a prairie planting rather than a specimen. Very easy from seed with a month of cold stratification.
Seed needs about 30 days of cold-moist stratification. Rhizomatous, spreads by root. See how to plant milkweed seed for the full method.
Cautions
Among the more toxic milkweeds to livestock relative to its size, because the whorled-leaved species concentrate cardenolides. Not a plant for a grazed paddock. More on milkweed toxicity.
Where whorled milkweed grows
Recorded in 42 states: Alabama, Arkansas, Arizona, Colorado, Connecticut, District of Columbia, Delaware, Florida, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Michigan, Minnesota, Missouri, Mississippi, Montana, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, Vermont, Wisconsin, West Virginia, Wyoming.
Distribution is generalized to state level. For county-level maps see USDA PLANTS and BONAP.
Frequently asked questions
Is whorled milkweed poisonous to livestock?
Yes. The narrow-leaved whorled milkweeds carry higher cardenolide concentrations by weight than broad-leaved species, and poisoning cases in sheep, cattle and horses are documented, usually from contaminated hay. Keep it out of pasture and hay ground.
Will whorled milkweed take over my garden?
It runs modestly by rhizome and seeds itself, but it is thin and easy to pull. In a dry prairie planting that is a feature, not a problem.
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 94722-1. Royal Botanic Gardens, Kew. Accepted name, authorship and global distribution.
- GBIF 3170235. Global Biodiversity Information Facility. Aggregated occurrence records.
- iNaturalist 125379. 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). Whorled Milkweed (Asclepias verticillata). Retrieved DATE, from https://milkweedusa.com/species/whorled-milkweed/
"Whorled Milkweed (Asclepias verticillata)." Milkweed USA, 2026, https://milkweedusa.com/species/whorled-milkweed/. Accessed DATE.
Milkweed USA. "Whorled Milkweed (Asclepias verticillata)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/species/whorled-milkweed/.
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title = {Whorled Milkweed (Asclepias verticillata)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/species/whorled-milkweed/},
note = {Accessed DATE}
}