Mentzelia albicaulis, whitestem blazing star



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Intermountain Flora
Annual or (in the s. part of its range) winter annual, (0.2) 1-3.5 (5) dm tall; herbage sparsely or evidently spreading-hirtellous with retrorsely barbed hairs, the stems sometimes glabrous, silvery-white or greenish-white; stem erect, brittle, freely branched, mostly from the base in well-developed plants, sometimes simple in smaller plants; leaves basal and cauline, the basal ones forming a rosette, petiolate, 3-15 cm long, up to 30 mm wide, usually deeply pinnatisect into slender, well-spaced segments, the cauline leaves often less cleft or the upper ones even entire and with a shorter (or no) petiole; flowers solitary in the axils of the leaves or in small clusters terminating the stem and branches, each flower individually subtended by 1 to few bracts, the bracts small, linear to narrowly lanceolate, entire or some with short lateral lobes, wholly green or rarely with a small white area at the base; calyx segments 1.7-3 mm long, lanceolate, divaricately spreading; petals 5, yellow or golden, often with a darker, orange or red-orange to salmon or red-brown area at the base, (3) 4-6 (7) mm long, obovate, often emarginate; stamens numerous, the filaments filiform; stlye 2-3 (4) mm long, persistent; capsule more or less erect, occasionally some of them curved near the base to about 90°, narrowly cylindrical but usually slightly expanded upwards, 8-22 mm long, 2-3 mm thick; seeds in more than one row, 1-1.5 mm long, irregularly ridged-angled, the ridges not grooved, or grooved on one of the ridges, evidentally papillate or tuberculate at 10x; 2n = 18, 36, 54, 72.

Cronquist, A., Holmgren, N.H., and Holmgren, P.K. (2005) "Intermountain Flora" pg. 108, vol. 2 part B, The New York Botanical Garden New York.