Species Native to Missouri
Common Name: purple milkweed
Type: Herbaceous perennial
Family: Apocynaceae
Native Range: Central and eastern North America
Zone: 3 to 8
Height: 2.00 to 4.00 feet
Spread: 1.00 to 3.00 feet
Bloom Time: May to July
Bloom Description: Rose-pink to purple
Sun: Full sun
Water: Dry to medium
Maintenance: Low
Suggested Use: Naturalize
Flower: Showy
Attracts: Butterflies
Tolerate: Deer, Drought, Erosion, Dry Soil, Shallow-Rocky Soil
Culture
Easily grown in average, dry to medium moisture, well-drained soils in full sun. Does well in poor, dryish soils. Drought tolerant. Can be propagated from seed. Not an aggressive spreader but can form an extensive, rhizomatous root system that is best left undisturbed.
Noteworthy Characteristics
Asclepias purpurascens, commonly called purple milkweed, is a herbaceous perennial that commonly occurs in dry to moist open woods, dry ridge tops, thickets, glades, prairie openings, stream banks and wet meadows throughout Missouri and other parts of the Midwest and eastern United States. It is similar in appearance to common milkweed (A. syriaca), except its flowers are deep rose pink, its leaves are more pointed, and it is not as aggressive of a spreader in garden conditions. It typically grows 2-4’ tall on stout, upright stems with heavy, pointed, short-stalked, ovate to oblong-lanceolate, opposite leaves (to 8” long). Leaves are dark green above and slightly pubescent below. Stems and leaves exude a milky sap when cut or bruised. Tiny, deep rose-pink flowers appear in many-flowered umbels in May-July. Each tiny flower (to 3/4” long) has 5 reflexed petals and 5 purple heads. Flowers give way to smooth seed pods (to 6” 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 purple.
Problems
No serious insect or disease problems. Aphids can be problematic but attempting to control them can result in inadvertent harm to monarch caterpillars and other beneficial insects.
Uses
Butterfly gardens, meadows, prairies, or naturalized/native plant areas.