Contr. U.S. Natl. Herb. 25: 363. 1925.
Plants winter-annual or biennial, candelabra-form. Stems solitary, erect, straight; branches distal or along entire stem, distal or proximal longest, antrorse, straight, proximal not decumbent; hairy or glabrescent. Leaves: blade (23–) 29–78.4 × 3–14.6 mm, widest intersinus distance 1.6–8.5 mm; proximal oblanceolate or elliptic, margins dentate to serrate, teeth 4–12, proximal sides slightly antrorse, distal sides perpendicular to leaf axis, 0.8–5.3 mm; distal oblanceolate, elliptic, lanceolate, or linear, base not clasping, tapered, margins usually dentate to serrate, rarely entire, teeth (0–) 2–10, proximal sides antrorse, distal sides perpendicular to leaf axis, 0.4–5.3 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, largest trichomes with pearly white bases, adaxial surface with needlelike trichomes. Bracts: margins entire. Flowers: petals golden yellow, 8.6–13.9 (–17.4) × 2.9–4.7 (–6.1) mm, apex rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 6.7–13.2 (–15.4) × 1.7–4.3 mm, usually without, rarely with, anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles 4.8–11.3 mm. Capsules cupshaped, 6.2–11.4 (–13) × 6–8.4 mm, base rounded, not longitudinally ridged. Seeds: coat anticlinal cell-walls wavy, papillae 5–13 per cell. 2n = 20.
Phenology: Flowering May–Sep.
Habitat: Roadsides, outcrops, hillsides, washes, dunes, sandy, gravelly, or volcanic soils.
Elevation: 800–1800 m.
Ariz., Nev., Utah.
Mentzelia integra is found in northwestern Arizona, southeastern Nevada, and southwestern Utah.