Ann. Missouri Bot. Gard. 21: 176. 1934.
Plants biennial or perennial, bushlike or candelabra-form, perennials with ground-level caudices. Stems solitary, erect, straight; branches distal or along entire stem, distal or proximal longest, antrorse, upcurved; hairy. Leaves: blade 35–112 × 4.3–27.1 mm, widest intersinus distance 2.3–15.3 mm, always on some leaves 4+ mm; proximal oblanceolate to elliptic, margins dentate to pinnate, teeth or lobes 12–30 (–50), perpendicular to leaf axis or antrorse, 1–9 mm; distal lanceolate, base not clasping, margins serrate to pinnate, teeth or lobes 8–28, perpendicular to slightly antrorse, 0.8–7.5 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and generally needlelike trichomes, adaxial surface with simple grappling-hook and needlelike trichomes. Bracts: margins entire or toothed to pinnate. Flowers: petals golden yellow, 11.3–20.4 × 2.9–7.2 [–8.9] mm, apex acute to rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 10.4–17.8 × 1.9–5.2 [–5.6] mm, with or without anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles (5.4–) 8.5–10.9 (–13) mm. Capsules cupshaped to cylindric, [7.6–] 9.1–16.4 × 5.7–9.2 mm, length usually to 2 times diam., sometimes a few more, base tapering to rounded, not longitudinally ridged. Seeds: coat anticlinal cell-walls straight or sinuous, papillae 4–106 per cell.
Ariz., Calif., Colo., N.Mex., Tex., Utah, n Mexico
Varieties 4 (3 in the flora).
Variety pinacatensis J. J. Schenk & L. Hufford is known from the Mexican state of Sonora.
|1||Seed coat anticlinal cell walls straight, papillae 4–6 per cell; margins of proximal leaf blades dentate.||Mentzelia longiloba var. chihuahuaensis|
|1||Seed coat anticlinal cell walls sinuous, papillae 10–106 per cell; margins of proximal leaf blades pinnate.||> 2|
|2||5 outermost stamens without anthers; leaf blade margin teeth or lobes perpendicular to leaf axis; seed coat cell papillae 67–106 per cell.||Mentzelia longiloba var. longiloba|
|2||5 outermost stamens with anthers; leaf blade margin teeth or lobes slightly antrorse; seed coat cell papillae 10–21 per cell.||Mentzelia longiloba var. yavapaiensis|
No values specified.