Asclepias asperula


Asclepias asperula, commonly called green-flowered milkweed or spider antelope horns, is a species of milkweed native to the Southwestern United States and northern Mexico.

Description

It is a perennial plant growing to 0.3–0.9 m tall, with clustered greenish-yellow flowers with maroon highlights. It blooms from April through June.

Taxonomy

Asclepias asperula is divided into two subspecies: asperula and capricornu, with the latter occurring in moister conditions and having wider leaves. Subspecies asperula occurs in drier and hotter habitat, thus its narrower leaves and lower maximum height.

Ecology

Like several other species of milkweed, A. asperula is a food for monarch butterfly caterpillars. Along with being a source of nutrition for monarchs, the plants also contain toxic cardiac glycosides that the monarchs retain, making them unpalatable and poisonous to predators. For the same reason, A. asperula can be poisonous to livestock and other animals, including humans.
In addition to the monarch, it is a larval host to the dogbane tiger moth, the queen butterfly, and the unexpected cycnia.

Cultivation

In cultivation, this species favors quickly-draining soil that is higher in inorganic matter, such as sand and rock chips. It can grow in loam and clay, if provided with adequate drainage and frequent-enough dryness. Moisture level demands and tolerance depend upon the subspecies and possibly ecotype. The plant has a deep taproot so it needs to have the deepest-possible pot if grown in a container and should not be waterlogged.