Asclepias asperula
antelopehorn milkweed
South-central and southwestern North America
Overview
Asclepias asperula is a clump-forming perennial milkweed native to the south-central and southwestern United States and northern Mexico. Several sprawling to upright stems rise 1-2 feet (30-60 cm) from a deep taproot, often leaning and curving along the ground. The narrow leaves are 4-8 inches (10-20 cm) long, irregularly folded and twisted, with a rough, hairy surface. From spring into summer the stems carry dense, rounded clusters 3-4 inches (8-10 cm) wide of greenish-yellow flowers tinged with maroon, each bloom showing the hooded, horned structure typical of milkweeds. Pollinated flowers form the paired, spindle-shaped pods that give the plant its common name antelope horns, splitting to release flat seeds carried on silky hairs. As with other milkweeds, the foliage is a larval food source for monarch butterflies and the flowers draw a range of bees and wasps. All parts contain milky latex with cardiac glycosides that are toxic to grazing livestock and to people if eaten. It grows in dry, open grassland and rocky ground, surviving heat and drought through its deep root but declining in wet or poorly drained soil.
Native Range
Native to the south-central and southwestern United States, from Kansas and Colorado south through Texas, New Mexico, and Arizona into northern Mexico. It grows in prairies, plains, rocky slopes, and open disturbed ground, usually in well-drained calcareous or sandy soil.Suggested Uses
Used in native plant, prairie, and pollinator gardens and in dry rock gardens and naturalized meadows. It suits hot, dry borders and restoration plantings aimed at supporting monarch butterflies.How to Identify
Appearance
Size & Dimensions
Height1' - 2'
Width/Spread1' - 2'
Reaches mature size in approximately 3 years
Bloom Information
Detailed Descriptions
Flower Description
Greenish-yellow with maroonFoliage Description
Gray-greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
