Sunset Crater blazingstar Sunset Crater blazingstar

Plants biennial, candelabra-form. Stems solitary, erect, straight; branches distal, distal longest, antrorse, straight; hairy. Leaves: blade 17.8–55.2 × 3–16.6(–26.3) mm, widest intersinus distance 1.4–4.9 mm; proximal oblanceolate, lanceolate, or elliptic, margins dentate to pinnate, teeth or lobes 8–18, perpendicular to leaf axis, 0.6–5.3 mm; distal elliptic to lanceolate, base not clasping, margins dentate to pinnate, teeth or lobes 4–12, perpendicular to leaf axis, 0.7–6.8 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, adaxial surface with simple grappling-hook and needlelike trichomes. Bracts: margins usually entire, occasionally toothed. Flowers: petals golden yellow, 8.5–16.2 × 2.6–6.4 mm, apex acute to rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, strongly clawed, (6–)9.9–13.8 × (1–)2.4–4.3 mm, without anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles (5–)7.8–11 mm. Capsules cylindric, 9.3–16.1 × 3.6–5.9 mm, base tapering, not longitudinally ridged. Seeds: coat anticlinal cell walls sinuous, papillae 51–59 per cell. 2n = 22.

Flowering Jun–Aug. Sparsely vegetated level ground, slopes, black (to sometimes reddish) volcanic cinder cone soils; of conservation concern; 1300–2500 m; Ariz.

Mentzelia collomiae is known only from the San Francisco Volcanic Field of Coconino County.