Asclepias tuberosa L.
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Authority
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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Family
Apocynaceae
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Scientific Name
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Description
Species Description - Ascending or erect, 3–7 dm, rather coarsely hairy, simple to much branched above; lvs numerous, alternate or on the branches opposite, linear to lanceolate or oblanceolate, 5–10 cm, cuneate to subcordate at base; juice not milky; umbels solitary and terminal to numerous; fls bright yellow to orange-red; cor-lobes 7–10 mm, the hoods 5–7 mm, greatly exceeding the gynostegium, nearly straight, erect, the lateral margins bearing an obscure tooth below the middle; fr 8–12 cm, erect; 2n=22. Prairies and upland woods, especially in sandy soil; s. N.H. to Fla., w. to Minn., S.D., Ariz., and Mex. June–Aug. Var. tuberosa, with the lvs typically widest above the middle, hence abruptly pointed, is the eastern phase of the sp., chiefly in and e. of the Appalachian Mts. in our range. Var. interior (Woodson) Shinners, with the lvs typically widest below the middle, hence tapering gradually to the tip, is more western, chiefly w. of the mts. in our range. Intermediates are abundant.
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Common Names
butterfly-weed