Woollypod Milkweed
Asclepias eriocarpa Benth.
A stout, woolly, cream-flowered California milkweed of dry hillsides and roadsides, with thick whorled leaves and densely hairy pods. Historically the most important fiber plant of several California Indigenous nations.
Also called Indian Milkweed, Kotolo.
- Height
- 2 ft–4 ft
- Spread
- 1.5 ft–3 ft
- Flowers
- cream, white
- Bloom
- May to August
- Light
- Full sun
- Soil moisture
- Dry
- USDA zones
- 7–10
- Leaves
- Whorled, oblong
- Sap
- Milky latex
- Roots
- Rhizomatous, spreads by root
- Stratification
- 30 days cold-moist
- Range
- 2 states
When it flowers
Woollypod Milkweed blooms May to August, peaking in June and July.
How to identify it
- Thick, wavy-edged leaves usually in whorls of three or four.
- Dense clusters of cream-white flowers with a waxy look.
- Pods conspicuously covered in white wool.
Unfamiliar words are in the glossary, and the identification key will narrow a plant down from what you can see.
The parts that identify it
Ecology and wildlife value
A major western monarch host across California’s interior valleys and foothills, and unusually high in cardenolides, which gives its larvae strong chemical defense.
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. Everything that lives on milkweed.
Growing woollypod milkweed
Drought-tolerant and long-lived, but coarse. Best in wilder parts of a California garden.
Seed needs about 30 days of cold-moist stratification. Rhizomatous, spreads by root. See how to plant milkweed seed for the full method.
Cautions
One of the most toxic North American milkweeds to livestock. More on milkweed toxicity.
Where woollypod milkweed grows
Recorded in 2 states: California, Nevada.
County records from USDA PLANTS, public domain. Cross-check against BONAP and your regional flora before making management decisions.
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 94258-1. Royal Botanic Gardens, Kew. Accepted name, authorship and global distribution.
- GBIF 3170253. Global Biodiversity Information Facility. Aggregated occurrence records.
- iNaturalist 58796. 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). Woollypod Milkweed (Asclepias eriocarpa). Retrieved DATE, from https://milkweedusa.com/species/woollypod-milkweed/
"Woollypod Milkweed (Asclepias eriocarpa)." Milkweed USA, 2026, https://milkweedusa.com/species/woollypod-milkweed/. Accessed DATE.
Milkweed USA. "Woollypod Milkweed (Asclepias eriocarpa)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/species/woollypod-milkweed/.
@misc{milkweedusa_specieswoollypodmilkweed,
title = {Woollypod Milkweed (Asclepias eriocarpa)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/species/woollypod-milkweed/},
note = {Accessed DATE}
}