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Asclepias asperula

antelopehorn milkweed

Apocynaceae

South-central and southwestern North America

Attracts Pollinators Attracts Butterflies Deer Resistant Drought Tolerant

Native to North America

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 5–9

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

Recognized by low, often sprawling stems and narrow, folded leaves with a rough texture. The flower clusters are rounded and greenish-yellow with maroon centers, each floret carrying the five-horned crown of a milkweed. Curved, paired seed pods resembling antelope horns and milky sap confirm the identification.

Appearance

Size & Dimensions

Height1' - 2'

Width/Spread1' - 2'

Reaches mature size in approximately 3 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~12 weeks

Spring Summer

Flowers open from March to June, sometimes again after summer rain. The rounded clusters are 3-4 inches (8-10 cm) across in greenish-yellow with maroon highlights. Bloom is followed by paired, upward-curving pods that ripen and split in late summer.

Detailed Descriptions

Flower Description

Greenish-yellow with maroon

Foliage Description

Gray-green

Growing Conditions

Sun Requirements

SunFull Sun

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

Soil Requirements

pH Range6.5 - 8.0(Alkaline)

357912

Soil Types

sand rocky loam chalk

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

2-3 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Grows in full sun and sharply drained sandy, gravelly, or limestone soil. It withstands extreme heat and long drought once the deep taproot forms, while standing moisture causes crown and root rot. Plants are hardy in USDA zones 5-9 and are slow to establish, putting early energy into the root before topgrowth. Direct sowing or planting while young works well, since the taproot makes transplanting older plants difficult. Watering is light and infrequent after the first season. The milky sap stains and contains compounds that irritate skin and eyes on contact.

Pruning

No routine pruning is needed. Stems can be cut back to the ground after the foliage dies down in autumn or left standing to self-seed. Spent pods may be removed before they split to limit volunteer seedlings.

⚠️ Toxicity Warning

Toxic to pets and humans

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Perennial

Asclepias asperula

antelopehorn milkweed

Apocynaceae

South-central and southwestern North America

Attracts Pollinators Attracts Butterflies Deer Resistant Drought Tolerant

Native to North America

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 5–9

Overview

Native Range

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.