Asclepias asperula (Decne.) Woodson
Antelope horns, Spider milkweed, Green-flowered milkweed, Spider antelope-horns
Asclepiadaceae (Milkweed Family)
USDA Symbol: asas
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 4–8 inches long, narrow, and irregularly grouped. The long, thick, narrow leaves are often folded lengthwise. As the green seed pods grow in length and begin to curve, they resemble antelope horns. Its pale, greenish-yellow flowers, tinged maroon, are crowded in round, terminal clusters 3–4 inches across at the end of the flower stem and are intricately arranged. Inside the partially divided petals is a crown, out of which extend 5 white stamens with large, ball-like anthers, all symmetrically arranged.
Milkweeds are the primary food source for Monarch caterpillars.
From the Image Gallery
Plant CharacteristicsDuration: Perennial
Root Type: Tap
Leaf Retention: Evergreen
Leaf Complexity: Simple
Leaf Shape: Lanceolate
Leaf Venation: Pinnate
Leaf Margin: Entire
Leaf Apex: Acute
Leaf Base: Truncate
Breeding System: Flowers Bisexual
Size Notes: Plant 1-2 ft tall. Follicles 4-13 cm long, 1-2.5 cm in diameter.
Size Class: 1-3 ft.
Bloom InformationBloom Color: White , Green
Bloom Time: Mar , Apr , May , Jun , Jul , Aug , Sep , Oct
DistributionUSA: AZ , CA , CO , ID , KS , NE , NM , NV , 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 ConditionsWater Use: Medium
Light Requirement: Sun
Soil Moisture: Dry , Moist
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.
BenefitUse 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 person’s 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 plant’s 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
Larval Host: Monarchs, Queens
Deer Resistant: High
Value to Beneficial InsectsSpecial Value to Native Bees
Special Value to Bumble Bees
Special Value to Honey Bees
Supports Conservation Biological Control
This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.
Butterflies and Moths of North America (BAMONA)
Learn more at BAMONA
Learn more at BAMONA
PropagationPropagation Material: Seeds
Description: Root cuttings can be taken in fall or early spring. Seeds may be sown outside in late fall or the following spring. Germination of spring-planted seeds is enhanced by moist stratification.
Seed Collection: Collect seed in June.
Seed Treatment: Stratify 3 months at 40 degrees. Germinates best in warmer half of the year.
Commercially Avail: yes
Find Seed or Plants
Order seed of this species from Native American Seed and help support the Wildflower Center.
Mr. Smarty Plants says
Medicinal plants at the Wildflower Center
April 19, 2006
What kinds of medicinal plants do you have at the Wildflower Center?
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Sources for seed of Utah native Asclepias labriformis
January 08, 2006
Hi there, I am looking for seeds of the plant "Asclepias labriformis" which is native to Utah. Can you help me to find seeds from this plant?
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From the National Suppliers DirectoryAccording to the inventory provided by Associate Suppliers, this plant is available at the following locations:
Wrights Nursery - Briggs, TX
From the National Organizations DirectoryAccording to the species list provided by Affiliate Organizations, this plant is on display at the following locations:
Fredericksburg Nature Center - Fredericksburg, TX
Lady Bird Johnson Wildflower Center - Austin, TX
NPSOT - Austin Chapter - Austin, TX
Jacob's Well Natural Area - Wimberley, TX
NPSOT - Williamson County Chapter - Georgetown, TX
Herbarium Specimen(s)NPSOT 0137 Collected Sept. 23, 1991 in Bexar County by Lottie Millsaps
BibliographyBibref 1186 - Field Guide to Moths of Eastern North America (2005) Covell, C.V., Jr.
Bibref 1185 - Field Guide to Western Butterflies (Peterson Field Guides) (1999) Opler, P.A. and A.B. Wright
Bibref 946 - Gardening with Prairie Plants: How to Create Beautiful Native Landscapes (2002) Wasowski, Sally
Bibref 765 - McMillen's Texas Gardening: Wildflowers (1998) Howard, D.
Bibref 281 - Shinners & Mahler's Illustrated Flora of North Central Texas (1999) Diggs, G. M.; B. L. Lipscomb; B. O'Kennon; W. F...
Bibref 248 - Texas Wildflowers: A Field Guide (1984) Loughmiller, C. & L. Loughmiller
Bibref 328 - Wildflowers of Texas (2003) Ajilvsgi, Geyata.
Bibref 286 - Wildflowers of the Texas Hill Country (1989) Enquist, M.
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Additional resourcesUSDA: Find Asclepias asperula in USDA Plants
FNA: Find Asclepias asperula in the Flora of North America (if available)
Google: Search Google for Asclepias asperula
MetadataRecord Modified: 2014-11-12
Research By: TWC Staff, RLU