Helianthella uniflora, one-headed sunflower

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Intermountain Flora Stems clustered on a branching caudex, 2-10 dm tall, harshly puberulent to spreading-hirsute, or glabrous below; leaves scabrous, lanceolate or elliptic, generally more or less triplinerved, up to 15 cm long and 5 cm wide, the lowermost ones oblanceolate and a little smaller than those above; heads erect, mostly solitary, sometimes 2 or 3, rarely more, the yellow disk mostly 1.5-3 cm wide; involucral bracts lance-linear or linear-oblong, acuminate to obtuse, scabrous-puberulent to hirsute and ciliate; rays sunflower-yellow, mostly about 13, sometimes up to 21, mostly 2-4.5 cm long and 5-10 mm wide; receptacular bracts firm; achenes strigose; 2n = 30.

Cronquist, A., Holmgren, A.H., Holmgren, N.H., Reveal, J.L., and Holmgren, P.K. (1994) "Intermountain Flora" pg.34, vol. 5, The New York Botanical Garden New York.