Lady Bird Johnson Wildflower Center - The University of Texas at Austin information

 Native Plant Database

Asclepias asperula

Antelope horns, Spider milkweed, Green-flowered milkweed, Spider antelope-horns

Asclepiadaceae (Milkweed Family)

Asclepias asperula (Antelope horns)
Marcus, Joseph A.
Asclepias asperula is a clump-forming, 1-2 ft. perennial with an upright or sprawling habit. Stems are densely covered with minute hairs. The leaves are 4Ė8 inches long, narrow, and irregularly grouped. The long, thick, narrow leaves are often folded lengthwise. As the green seed follicles grow in length and begin to curve, they are said to resemble antelope horns, thus one of its vernacular names.

Milkweed species are the food source for Monarch butterfly caterpillars.

Image Gallery:

45 photo(s) available

Plant Characteristics

Duration: Perennial
Habit: Herb
Root Type: Tap
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Leaf Shape: Lanceolate
Leaf Venation: Pinnate
Leaf Margin: Entire
Leaf Apex: Acute
Leaf Base: Truncate
Breeding System: Flowers Bisexual
Fruit Type: Follicle
Size Notes: Plant 1-2 ft tall. Follicles 4-13 cm long, 1-2.5 cm in diameter.
Leaf: Green
Size Class: 1-3 ft.

Bloom Information

Bloom Color: White , Green
Bloom Time: Mar , Apr , May , Jun , Jul , Aug , Sep , Oct


USA: AZ , CA , CO , ID , KS , NE , NV , NM , OK , TX , UT
Native Distribution: C. Kansas to Texas and Mexico, west to s. Idaho and se. California.
Native Habitat: Meadows, along roadsides, Blackland Prairie to Edwards Plateau. Well-drained caliche, loam, sand, clay.

Growing Conditions

Water Use: Medium
Light Requirement: Sun
Soil Moisture: Moist , Dry
Soil Description: Prefers rocky or sandy soils of prairies, pastures, plains, hillsides, brushlands, and woodlands.
Conditions Comments: The Antelope-horns have interesting and robust flower heads. The common name is derived from the curved form of the seed pods. Antelope-horns will inevitably have aphids. The insects are not a problem unless the plant looks sick; at that point an effective treatment is to spray the plant and aphids with soapy water. Another possible treatment is to support the plant part with your hand and blast it with high-pressure water.


Use Ornamental: Antelope-horns is a milkweed plant that spreads out along the ground and grows 8 to 24 inches in height.
Use Wildlife: This plant is attractive to bees, butterflies and/or birds. This species of milkweed attracts huge bees as pollinators.
Warning: This plant is reported to be toxic to animals, and like other plants in the genus Asclepias is probably also poisonous to humans. The sap of some causes skin irritation in humans. Sensitivity to a toxin varies with a personís age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plantís different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.
Conspicuous Flowers: yes
Attracts: Butterflies
Larval Host: Monarchs, Queens
Deer Resistant: High

Butterflies and Moths of North America (BAMONA)

Asclepias asperula is a larval host and/or nectar source for:
(Danaus plexippus)

Larval Host
Learn more at BAMONA
(Danaus gilippus)

Larval Host
Learn more at BAMONA

Last Update: 2015-07-29