Asclepias asperula aka Antelope Horns

Asclepias asperula is a perennial in the dogbane family, Apocynaceae. Its common names include spider milkweed and antelope horns. Trailing milkweed is another name for this species. Its native range spans the western and central United States into northern Mexico. It grows in sandy or rocky soils that contain lime. Kew places it in the temperate climate group.

Plants reach about 2 feet (0.6 metres) tall and wide. Growth proceeds at a moderate rate. The plant has a loose, spreading or sprawling form. This low shape suits beds and the front of borders. PFAF also lists it for mass planting or single specimens. The supplied species evidence gives no clear leaf or stem details. It does not describe the shape of the fruit.

The flowers are white and draw bees and other insects. Butterflies and moths also help pollinate them. Each flower has both male and female organs. PFAF gives July to August as the flowering period. Its summary also mentions bloom from late spring into summer. Seed ripens from August to October. The plant offers value in gardens planned to attract wildlife. Its flowers also provide nectar, according to PFAF.

Choose a sunny site with soil that drains well. PFAF also reports that the plant can tolerate light shade. Sandy and loamy soils suit it, across a broad pH range. It accepts dry or moist soil. However, PFAF's growing notes also recommend rich or peaty, moist ground. These accounts suggest some variation in reported growing needs. PFAF lists USDA hardiness zones 5–9. Avoid disturbing the roots when planting or dividing established plants. Sow ripe seed in autumn, or sow in late winter. Stored seed may need two to three weeks of cold treatment. Germination can take one to three months at 18°C. PFAF advises protecting young plants from slugs as they establish.

PFAF reports cooked leaves, flowers and stalks as edible parts. It also records a traditional use for nasal congestion. These reports do not establish safe home use. The same source says this species can poison livestock. Its food rating should not obscure that warning. Much of its further material-use discussion concerns other milkweeds. Those uses cannot be assigned to this species from this evidence.