Skip Navigation

Species Search:
FieldGuidesthreatened and/or endangered search resultsthreatened and/or endangered

previous  | next

Poison Milkweed Asclepias subverticillata


enlarge +

Poison Milkweed
credit: Jerrry Oldenettel/CCSA

All Images


Get Our Newsletters


Advanced Search

Alternate name: Horsetail Milkweed

Family: Asclepiadaceae, Milkweed view all from this family

Description Native herbaceous perennial. Multiple slender erect stems on stout semi-woody semi-rhizomatous rootstock. To 3' H x 6" W. Leaves whorled, narrow, lanceolate. White to cream colored flowers produced in umbels along upper portion of the stems in summer. May form large stands.

Milky-white sap is toxic to livestock, but the plant attracts butterflies.

Other common names: Western whorled milkweed, horsetail milkweed.

Warning This unpalatable species is very poisonous to livestock, and when better forage is unavailable, animals may eat Poison Milkweed, often with fatal results. All plants in the genus Asclepias are probably somewhat
toxic to both humans and animals. The sap of some causes skin irritation in humans. Sensitivity to a toxin varies with a personís age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plantís different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.

Flower Summer, May - September.

Habitat Low to medium water, full sun, loamy soil, very hardy.

Range Kansas to Idaho, south to Arizona, New Mexico, Trans-Pecos Texas, and northern Mexico.