Silphium laciniatum 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
Asteraceae
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Scientific Name
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Description
Species Description - Coarse, taprooted, rough-hairy, 1–3 m; lvs alternate, deeply pinnatifid or bipinnatifid, the lower very large, to 5 dm, progressively reduced upwards, the uppermost entire and well under 1 dm; heads in a narrow, sometimes racemiform infl, large, the disk 2–3 cm wide; invol 2–4 cm, exceeding the disk, its bracts ovate, acuminate, squarrose, not much imbricate; rays (13–)17–25(–34), 2–5 cm; 2n=14. Prairies; O. to Minn. and S.D., s. to Ala. and Tex.; locally intr. e. along railroads to N.Y. July–Sept. The basal lvs tend to align themselves in a north-south direction.
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Common Names
Compass plant