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Native Plant Society of Texas

Antelope Horn Milkweed

Asclepias asperula

Other common name(s):

Antelope-horns, Spider Milkweed, Green-flowered Milkweed, Spider Antelope-horns, Antelope Horns

Family:

Apocynaceae (Dogbane Family)

Plant Ecoregion Distribution Map

This map uses data from the US EPA. EPA  servers have been offline frequently so maps may not display. We are working on a solution.

Chihuahuan Deserts, Cross Timbers, Edwards Plateau, High Plains, Southwestern Tablelands, Texas Blackland Prairies
Chihuahuan Basins and Playas, Chihuahuan Desert Grasslands, Chihuahuan Montane Woodlands, Low Mountains and Bajadas, Stockton Plateau
Carbonate Cross Timbers, Eastern Cross Timbers, Grand Prairie, Limestone Cut Plain, Western Cross Timbers
Balcones Canyonlands, Edwards Plateau Woodland, Llano Uplift, Semiarid Edwards Plateau
Llano Estacado
Canadian/Cimarron Breaks, Caprock Canyons Badlands Breaks, Flat Tablelands and Valleys, Semiarid Canadian Breaks
Floodplains and Low Terraces1, Northern Blackland Prairie, Southern Blackland Prairie

Plant Characteristics

Growth Form

Herbaceous

Height

1
to
2
ft.

Spread

1
to
2
ft.

Leaf Retention

Deciduous

Lifespan

Perennial

Habitat and Care Requirements

Soil Type(s)

Sand, Loam, Caliche, Well Drained, Moist, Dry

Light Requirement

Sun

Water Requirement

Medium

Native Habitat

Grassland

Bloom and Attraction

Bloom Color

White, Green

Bloom Season

Spring, Summer, Fall

Seasonal Interest

Nectar, Larval Host

Wildlife Benefit

Butterflies, Bees

Maintenance

Very little maintenance needed. Drought tolerant. Perfect for sunny borders, cottage gardens, butterfly gardens, and prairies or naturalized areas. Avoid rich, heavily fertilized soils. Flowers heavily in spring, and sporadically summer through fall. Will inevitably have aphids, but not a problem unless the plant looks sick. Treat aphids with soapy water not pesticides. WARNING: milky sap can irritate skin and eyes and are toxic to humans and pets. Propagation: cutting, seed, root division.

Comments

Blooms March-October. Clump forming, upright, or sprawling. Stems densely covered with hairs. The long, thick, narrow leaves are folded lengthwise. Flowers are clustered in balls at the end of branches. The green seed pods curve as they grow in length, and are said to resemble antelope horns, thus its common name. Produces abundant seeds attached to feathery tufts. Although still listed by some in the Asclepiadaceae Family, the majority of botanical organizations now list it in the Apocynaceae Family. Larval host: Queen and Monarch butterflies.

References

Learn about how to propagate Texas native plants.

Material Treatment Method Collection References
Seed Stratification Start indoors after cold stratifying the seeds in a refrigerator for 3-4 weeks. Some individuals may bloom the first year, but they often start blooming after their first winter. Also, seeds can be soaked overnight in water. Cold moist stratification involves chilling the seeds at 40 degrees for up to three months. Seeds can be collected in June from established plants or can be ordered online. 1) https://www.grandprismaticseed.com/natives/antelope-horns-milkweed#:~:text=Direct%20sow%20seeds%20in%20autumn,blooming%20after%20their%20first%20winter. 2) https://monarchbutterflygarden.net/milkweed-for-monarchs/asclepias-asperula-antelope-horns/ 3) https://txmn.org/goodwater/2017/04/19/antelope-horns-milkweed-for-monarchs/
Root Cutting, Division Carefully dig up the plant and separate into smaller sections. Each section should have several shoots and a portion of the root. Replant the sections in well draining soil. Keep the soil moist until the plants become well established. Root cuttings can be done in late fall or early spring. 1) https://txmn.org/goodwater/2017/04/19/antelope-horns-milkweed-for-monarchs/ 2) https://www.gardenia.net/guide/learn-how-to-plant-care-and-grow-milkweed
Seed No Treatment Sowing seeds in late fall also allows this exposure to moist cold conditions. Use plastic flats or seedling trays. Fill them 3/4 with potting soil. Scatter the seeds on the soil surface 1/2 inch apart. Cover with 1/4 inch of soil mix. Water thoroughly and place them in a sunny window or under grow lights. Most seeds will germinate in 7-10 days if the flats are maintained at 75 degrees Fahrenheit. After the seeds have germinated and are 3-6 inches tall, they are ready to be transplanted to your garden. Plant the seedlings 6-24 inches apart., depending on the species. 1) https://txmn.org/goodwater/2017/04/19/antelope-horns-milkweed-for-monarchs/ 2) https://www.gardenia.net/guide/learn-how-to-plant-care-and-grow-milkweed
Stem Cutting Cut a 4-6 inch section of stem and remove the lower leaves. Dip the cut end of the stem in rooting hormone and plant in a container with moist potting soil. Ensure the cuttings have adequate moisture and light to encourage root development. The transplant to your garden. Cuttings can be taken during in late fall or early spring.. 1) https://earthone.io/plant/asclepias%20asperula?srsltid=AfmBOoo9Kbmlw30nA5YMDjK97ITIPfCuPeabxzlOUjAgGysA5m4do9pL 2) https://www.gardenia.net/guide/learn-how-to-plant-care-and-grow-milkweed

About the Region

Fall Symposium 2025 Logo - Teach for the Future

Salado, the location of our Fall 2025 Symposium, lies at the intersection of two ecoregions: the Edwards Plateau (Limestone Cut Plain) and Blackland Prairie (Northern Blackland Prairie).

The Edwards Plateau area is also called the Hill Country; however, this general term covers a much larger area extending farther north. Spring-fed creeks are found throughout the region; deep limestone canyons, rivers, and lakes (reservoirs) are common. Ashe juniper is perhaps the most common woody species found throughout the region. Additional woody species include various species of oak, with live oak (Quercus fusiformis) being the most common. Sycamores (Platanus occidentalis) and bald cypress (Taxodium distichum) border waterways. This area is well known for its spring wildflower displays, though they may be viewed in spring, late summer, and fall, as well. According to Texas Parks and Wildlife, average annual rainfall in the Edwards Plateau ranges from 15 to 34 inches.

The Blackland Prairie extends from the Red River south to San Antonio, bordered on the west by the Edwards Plateau and the Cross Timbers, and on the east by the Post Oak Savannah. Annual rainfall averages 30 to 40 inches, with higher averages to the east. This region is dominated by prairie species. The most common grass species include little bluestem (Schizachyrium scoparium) and Indian grass (Sorghastrum nutans) in the uplands and switchgrass (Panicum virgatum) in the riparian areas and drainages. Common herbaceous flowering plants include salvias, penstemons, and silphiums. This area has suffered greatly from overgrazing and agricultural use. Few intact areas remain, though many of the plants can be found along county roadsides throughout the region.

Our fall Symposium host chapter, the Tonkawa Chapter, includes both of these ecoregions.

Source: Wildflowers of Texas by Michael Eason