W. C. Hodgson & L. Hufford, Brittonia 65: 410, figs. 1,2. 2013.
Plants perennial, bushlike, with subterranean caudices or rhizomes. Stems multiple, erect or decumbent, zigzag; branches along entire stem, all ± equal, antrorse, upcurved; hairy. Leaves: blade 16–31 × 3.9–9.2 mm, widest intersinus distance 3–-8.3 mm; proximal oblanceolate to elliptic, margins entire or dentate, teeth 0–4(–6), perpendicular to leaf axis, 0.2–1.3 mm; distal oblanceolate to elliptic, base not clasping, margins entire or dentate, teeth 0–4, perpendicular to leaf axis, 0.4–2 mm; abaxial surface with simple grappling-hook (occasionally absent) and complex grappling-hook trichomes, adaxial surface with complex grappling-hook and needlelike trichomes. Bracts: margins entire. Flowers: petals white, 9–15 × 1.8–2.4 mm, apex rounded to acute, glabrous abaxially; stamens white, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 7.1–13 × 0.5–1.4 mm, with anthers, second whorl with anthers; anthers twisted or straight after dehiscence, epidermis papillate; styles 4.8–-7.3 mm. Capsules cup-shaped, 4.5–8(–13) × 4.5–7 mm, base rounded, not longitudinally ridged. Seeds: coat anticlinal cell walls straight, papillae usually 6–9 per cell.
Phenology: Flowering May–Nov.
Habitat: Loose, rocky soils primarily on steep, degraded slopes, less frequently on stream bottoms, Muav limestones and Bright Angel shales.
Elevation: 800–1600 m.
Mentzelia canyonensis is known only from the Grand Canyon and Little Colorado River canyon in Coconino County.