Plant of the Week

Asclepias tuberosa range map.
Asclepias tuberosa range map. USDA PLANTS Database.

Asclepias tuberosa
Butterfly milkweed (Asclepias tuberosa). Photo by Larry Stritch.

Butterfly Milkweed (Asclepias tuberosa L.)

By Larry Stritch

Butterfly weed is a member of the milkweed family (Asclepiadaceae). The genus name Asclepias is named after the Greek god of medicine Asklepios. The species name tuberose refers to the tuberous (knobby and with swellings) roots.

Butterfly weed grows commonly in dry open habitats and is very common in the prairies and grasslands of the Midwest and Great Plains. This beautiful native wildflower is found from Maine to South Dakota to the desert southwest to Florida.

Native Americans harvested fibers from the dried stems that were made into ropes and used in weaving cloth. Many tribes used various parts of the butterfly weed as food. In colonial America, dried leaves of butterfly weed and skunk cabbage were made into a tea to treat chest inflammations thus giving butterfly weed an alternative name: pleurisy root. Pleurisy root was listed in the American Pharmacopoeia and the National Formulary until 1936.

Butterfly weed is a coarse perennial forb consisting of many stems. The stems are straight and very hairy. The leaves are alternate and simple. Unlike other species of milkweed butterfly weed does not contain the characteristic thick milky sap but instead has a watery translucent sap. The inflorescence is slightly rounded to flat and made up many individual flowers. The flower consists of five petals pointing down and topped by a crown of five erect hoods. The fruit is a pod containing numerous brown seed each with a tuft of silky white hairs. Many a child and adult have gleefully pulled the seeds from a ripened, opened pod and let them float gracefully on a gentle breeze.

Butterfly weed is commonly planted in formal garden borders and in meadow and prairie gardens. This wildflower does not transplant well as it has a deep woody taproot. It is easily propagated from seed. Collect the seed from the pods has they just begin to open. Butterfly weed seed need a three-month cold stratification. Therefore, it is best to plant the seed in autumn and they will easily germinate the following spring.

For More Information

Asclepias tuberosa.
Butterfly milkweed (Asclepias tuberosa). Photo by T.G. Barnes.

Asclepias tuberosa.
Butterfly milkweed (Asclepias tuberosa). Photo by Daniel Reed, courtesy of the University of Tennessee Herbarium.

Asclepias tuberosa.
Butterfly milkweed (Asclepias tuberosa). Photo by Elaine Haug, courtesy Smithsonian.

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Louisiana Trillium (Trillium ludovicianum).
Louisiana Trillium (Trillium ludovicianum)