Madroño 57: 253, fig. 4A. 2010.
Plants biennial, bushlike or candelabra-form. Stems solitary, erect, straight; branches distal or along entire stem, distal or proximal longest, antrorse, straight; hairy. Leaves: blade 32.8–112.2 × 2.9–11.4 mm, widest intersinus distance 1–2.9 mm; proximal oblanceolate to elliptic, margins pinnate, lobes 18–24, perpendicular to leaf axis, 0.8–4 mm; distal elliptic to lanceolate, base not clasping, margins pinnate, lobes 6–16, perpendicular to leaf axis, 1–5.1 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, adaxial surface with needlelike and occasionally simple grappling-hook trichomes. Bracts: margins entire. Flowers: petals light to golden yellow, 9–14.7 × 3.1–6.4 mm, apex rounded, glabrous abaxially; stamens light to golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 6.3–11.5 × 2.4–4.9 mm, with anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles 4.6–9.9 mm. Capsules cupshaped, 8.2–12.7 × 5.1–7.7 mm, base tapering to rounded, not longitudinally ridged. Seeds: coat anticlinal cell-walls sinuous, papillae 12–21 per cell. 2n = 18.
Phenology: Flowering Jun–Aug.
Habitat: Knolls, slopes, and grassland roadsides, gypsum or brown clayey soils.
Elevation: 1500–1900 m.
Mentzelia sivinskii is known from La Plata County, Colorado, and Rio Arriba and San Juan counties, New Mexico.