Asclepias speciosa
Species Native to Missouri
Common Name: showy milkweed
Type: Herbaceous perennial
Family: Apocynaceae
Native Range: Western North America
Zone: 3 to 9
Height: 1.00 to 3.00 feet
Spread: 1.00 to 1.50 feet
Bloom Time: May to June
Bloom Description: Purplish rose
Sun: Full sun
Water: Dry to medium
Maintenance: Low
Suggested Use: Naturalize
Flower: Showy
Attracts: Hummingbirds, Butterflies
Tolerate: Deer, Drought
Culture
Easily grown in average, dry to medium, well-drained soils in full sun. Drought tolerant. Does well in poor, dryish, gravelly soils. Easily grown from seed, and may self-seed in the landscape if seed pods are not removed prior to splitting open. Once established, it is best to leave plants undisturbed because they develop deep taproots which make transplanting difficult.
Noteworthy Characteristics
Asclepias speciosa, commonly called showy milkweed, is a rough, weedy perennial which commonly occurs on dry slopes, open woodland areas, roadsides, waste areas and along streams in western North America. It typically grows 2-4' tall on stout, upright stems with velvety, broad-oblong to broad-ovate, gray-green leaves (to 8" long) with conspicuous veining. Globular clusters (umbels to 3" across) of fragrant, pinkish-white to pinkish-purple, star-like flowers appear mostly in the upper leaf axils over a long bloom period from late spring well into summer. Stems and leaves exude a milky sap when cut or bruised. Flowers give way to prominent, rough seed pods (2-3" long) which split open when ripe releasing their numerous silky-tailed seeds for dispersal by the wind. Seed pods are valued in dried flower arrangements. Flowers are a nectar source for many butterflies and leaves are a food source for monarch butterfly larvae (caterpillars).
The charismatic and imperiled monarch butterfly requires milkweed plants in order to survive. Monarchs migrate into the eastern U.S. from Mexico in spring to lay their eggs on milkweed species plants. Caterpillars hatch from the eggs and consume the milkweed plant foliage as food for growth and development. Mature caterpillars will search for a nearby, sheltered location to enter the pupal stage and form a chrysalis. Inside, they will complete metamorphosis and emerge as an adult butterfly in around 2 weeks. Flower nectar is consumed by adult butterflies as a valuable food source. The 4th or 5th generation of monarch butterflies that emerges in August-September will migrate into Mexico to overwinter as adults. Significant declines in monarch butterfly populations in North America over the course of the 21st century are believed by many experts to be caused by a reduction in milkweed due to widespread use of herbicide-tolerant row crops, climate change, and loss of overwinter sites due to habitat destruction.
To support monarch butterflies, plant species of milkweed that are native to your area.
Genus name honors the Greek god Asklepios the god of medicine.
Specific epithet means showy.
Problems
No serious insect or disease problems. Somewhat weedy in appearance, but less spreading and a more manageable garden plant than common milkweed (Asclepias syriaca). Aphids can be problematic but attempting to control them can result in inadvertent harm to monarch caterpillars and other beneficial insects.
Uses
Borders, rock gardens, butterfly gardens, prairies, meadows or naturalized/native plant areas.