Asclepiadaceae: Asclepias syriaca

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Family Name

Asclepiadaceae

Common Name

Common milkweed

Native American Name

Lakota: pȟanúŋpala waȟčáȟča

Description

Asclepias syriaca is a perennial herb with milky white sap, growing from a deep rhizome with solitary stems that are simple or occasionally branched, growing 0.6 to 2 m in height and densely covered in hairs toward the top. The simple leaves are usually opposite with a short petiole 2-13 mm in length. The blades are broadly lanceolate to ovate. 6-30 cm long and 5-11 cm wide, margins entire, with a thick covering of hairs on the underside. The inflorescences are few to several in the upper leaf axils, each coming from a 1-14 cm peduncle 1.5-4.5 cm long that have 20 to130 flowers attached by 1-3 cm long pedicels that are covered with short hairs. The flowers are 11-17 mm long, the calyx is green to purple, covered with hairs and with 5 lobes that are 2.4-4 mm long. The purple to rose to rarely white colored corolla lobes are rounded, reflexed and 9-15 mm long the apex is attenuated looking like a crown. The fused stamens and pistil os pale rose to pinkish-cream colored, broadly obconic 1-1.9 mm tall and 1.5-2.5 mm wide. The fruit are erect follicles that are 7-11 cm long and 2-3.5 cm wide. The seeds are ovate 6-8 mm long with long white to brownish hairs. Common milkweed blooms from May through August on the banks of lakes, ponds and streams or moist areas on prairies and along roadsides throughout much of South Dakota. Showy milkweed and common milkweed are very similar. They can be distinguished by their flower petals, with A. speciosa having longer narrower petal lobes that give the flower the appearance of a crown.

Additional Notes

Common milkweed is an attractive addition to a native plant garden and an important food source for the monarch butterfly caterpillar. The flowers attract butterflies, bumblebees and hummingbirds to the garden. Young shoots, leaves and seed pods are all edible if cooked. Extracting the milky latex is accomplished by placing plant materials in cold water and bringing them to a boil. They can then be steamed, boiled or fried.

Horticulture Notes

Seed Collection: Seeds turn brown and are released from the pods over an extended period. The seeds in open pods often have milkweed buds and care should be taken or they will consume stored seeds. Unopened brownish pods that split when gently squeezed are the best source.

Germination: Seeds require 30 days of cold moist stratification before planting in the spring. Seeds planted in the fall will germinate in the following spring.

Vegetative propagation: Established plants can be divided in late spring and transplanted.

Light: Full sun.

Soil: Tolerate a wide range of soils but prefers a well-drained sandy loam.

Water: Medium to dry conditions.