Uintah blazingstar Uintah blazingstar

Mentzelia multicaulis (Osterhout) J. Darlington var. uintahensis N. H. Holmgren & P. K. Holmgren, Syst. Bot. 27: 758, fig. 5. 2002

Plants perennial, bushlike, with subterranean caudices or rhizomes. Stems multiple, erect, zigzag or straight; branches distal or along entire stem, distal longest or all ± equal, antrorse, upcurved; hairy. Leaves: blade 17–56 × 5.8–28 mm, widest intersinus distance 1–4.9(–6) mm; proximal oblanceolate to elliptic, margins pinnate to pinnatisect, lobes 4–12, antrorse, 1.9–7.7 mm; distal elliptic to lanceolate, base not clasping, margins pinnate to pinnatisect, lobes 4–12, antrorse, 2.6–13.3 mm; abaxial surface with simple grappling-hook and occasionally complex grappling-hook and needlelike trichomes, adaxial surface with simple grappling-hook and needlelike trichomes. Bracts: margins entire. Flowers: petals golden yellow, 8.5–15.2 × 3.8–7.9 mm, apex acute to rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments broadly spatulate, strongly clawed, 5–10.4 × 2.8–6 mm, with anthers, second whorl with anthers; anthers usually twisted after dehiscence, epidermis smooth; styles 5.8–8.5 mm. Capsules cup-shaped, 4.2–8.8 × 3.6–5.8 mm, base tapering to rounded, not longitudinally ridged. Seeds: coat anticlinal cell walls straight, papillae 4–7 per cell. 2n = 22.

Flowering May–Sep. Sparsely vegetated steep talus slopes and roadcuts; 1500–2800 m; Colo., Utah.

Mentzelia uintahensis is known from northwestern Colorado (Rio Blanco, Mesa, and Moffat counties) and northeastern Utah (Carbon, Duchesne, and Uintah counties).