Asclepias tuberosa Linnaeus, Apocynaceae

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Primarily a threat at high elevations?  no

Risk assessment results:  High risk; score: 7 (Hawaii-Pacific Weed Risk Assessment for Asclepias tuberosa)

Other Latin names:  Asclepias decumbens L.

Common name(s): [more details]

English: butterfly milkweed, butterfly-weed, chieger-flower, pleurisy-root

Habit:  herb

Description:  "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." (USDA Forest Service)

Habitat/ecology:  "Butterfly weed [PIER ed.: Asclepias tuberosa&nbsb;L.] grows commonly in dry open habitats and is very common in the prairies and grasslands of the Midwest and Great Plains. . . .does not transplant well as it has a deep woody taproot. It is easily propagated from seed. . . . Butterfly weed seed need a three-month cold stratification." (USDA Forest Service)

Propagation:  "It [PIER ed.: Asclepias tuberosa&nbsb;L.] 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." (USDA Forest Service)

Native range:  Eastern Canada, eastern and southern U.S., northern Mexico (GRIN)

Impacts and invaded habitats:  (no invaded habitats or impacts known by PIER; please let us know if you know of such information we should add here)

Presence:

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Mexico Mexico	Mexico (United Mexican States)	native	GRIN (year unknown)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	native	GRIN (year unknown)
United States of America United States	United States	invasive	Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (X)=present as a weed (but importance rank unknown)
United States (continental except west coast) United States (other states)	United States (other states)	native	GRIN (year unknown)

Control:  If you know of control methods for Asclepias tuberosa, please let us know.