Grindelia squarrosa (Pursh) Dunal
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Glabrous biennial or short-lived perennial 1–10 dm, branched at least above; lvs abundantly punctate; heads several or many, the disk 1–2 cm wide; invol bracts strongly resinous, imbricate in several series, the green tips (especially of the outer) squarrose-reflexed; rays 25–40, 7–15 mm, rarely absent; achenes 2–3 mm; pappus-awns 2–8, finely serrulate to subentire; 2n=12, 24. Open or waste places; Man. and Minn. to B.C., Nev., and Tex., and widely intr. elsewhere. July–Sept. The southwestern var. nuda (A. W. Wood) A. Gray, with discoid heads, is not a regular member of our flora.