Spider milkweed, Antelope horns, Green-flowered milkweed, Spider antelope-horns
Asclepiadaceae (Milkweed Family)
Marcus, Joseph A.
Spider antetope-horns 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.
Image Gallery: 47 photo(s) available
Plant CharacteristicsDuration: Perennial Habit: Herb 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. Leaf:
Fruit: Size Class:
Bloom InformationBloom Color: White , Green
Bloom Time: Mar , Apr , May , Jun , Jul , Aug , Sep , Oct
, 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:
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.
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.
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:
Butterflies Larval Host:
Monarchs, Queens Deer Resistant:
Butterflies and Moths of North America (BAMONA)
is a larval host and/or nectar source for: