Taxon

Asclepias subverticillata

 
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Asclepias subverticillata - horsetail milkweed, poison milkweed, hierba lechosa, talayote
Image: Western New Mexico University Department of Natural Sciences and the Dale A. Zimmerman Herbarium
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Common name: horsetail milkweed, poison milkweed, hierba lechosa, talayote
Family: Apocynaceae (Dogbane)
Distribution: Central and Western United States, Northern Mexico
Habitat: Plains, deserts, roadsides, open woodlands
Hardiness: USDA Zone 5 (-20 to -10 °F)
Life form: Herbaceous perennial
Occurrence in New Mexico: New Mexico native plant
Growing Conditions: This important food source for the Monarch butterfly grows in many habitats in the Southwest, at elevations from 3,100-7,800 feet. The horsetail milkweed is widespread in New Mexico on plains and mesas, in piñon-juniper woodlands and ponderosa pine forests, and along streams and roadsides. It is frequently seen in the Chihuahuan Desert growing in low areas that collect water during the monsoon season. It grows in full sun or part shade. It often grows in dry, infertile soil, but may spread by rhizomes to form colonies in moist, fertile soil.
Description: Horsetail milkweed usually grows about 15 inches tall but sometimes reaches 4 feet. Stems may be unbranched or with multiple branches, and like other milkweeds, contain milky latex. It is easily recognized by narrow (less than ¼ inch across) lance-shaped or linear leaves with rolled margins. Three to four leaves emerge from each stem node, and are almost whorled (hence subverticillata) around the stems. Throughout summer, small clusters (umbels) of white, greenish or purple star-like flowers emerge from lateral and upper leaf axils. The fruit is a broad, smooth pod filled with many seeds that have long, silky hairs. This spreading milkweed is often seen in large patchy stands.
Links: SFBG Plant of the Month • Germplasm Resources Information Network (GRIN-Taxonomy) • NatureServe Explorer • SEINet • Wildflower Center - Native Plant Database

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