Grindelia squarrosa, curlycup gumweed

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Intermountain Flora
Biennial or short-lived perennial, 1-10 dm tall; leaves regularly callous-serrulate to sometimes (var. quasiperennis) more coarsely toothed or even entire, the middle or upper ones mostly clasping; involucre strongly resinous, regularly imbricate, the slender green tips of all but the innermost bracts squarrose-reflexed; rays mostly 25-40, occasionally fewer on some heads of small plants, commonly 7-15 mm long; achenes generally truncate at the summit; 2n = 12.

Cronquist, A., Holmgren, A.H., Holmgren, N.H., Reveal, J.L., and Holmgren, P.K. (1994) "Intermountain Flora" pg.256, vol. 5, The New York Botanical Garden New York.