Mentzelia rusbyi

Plants biennial or perennial, candelabra-form, perennials with ground-level caudices. Stems solitary, erect, straight; branches distal, distal longest, antrorse, straight; hairy. Leaves: blade 41–123 × 6.4–26.4 mm, widest intersinus distance 4.8–18 mm; proximal spatulate, elliptic, or lanceolate, margins dentate, teeth 10–24, perpendicular to leaf axis, 0.6–3.6 mm; distal lanceolate, base not clasping, margins dentate, teeth 10–22, perpendicular to leaf axis, 1.2–6 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, adaxial surface with simple grappling-hook and needlelike trichomes. Bracts: margins pinnate. Flowers: petals light yellow, 11.8–23.8 × 3–6.9 mm, apex acute, glabrous abaxially; stamens light yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 9.2–19.5 × 1.5–4.5 mm, usually without, rarely with, anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles 9–14 mm. Capsules cylindric, (13–) 18.8–29 × 7–10.5 mm, base tapering to rounded, longitudinally ridged. Seeds: coat anticlinal cell-walls sinuous, papillae 23–54 per cell. 2n = 20.

Phenology: Flowering Jul–Aug(–Sep).
Habitat: Mesic habitats, moist washes, roadsides, roadcuts, steep to gentle slopes, disturbed sites, rocky soils composed of sand and loam.
Elevation: 1800–3100 m.

Ariz., Colo., N.Mex., Utah, Wyo.

Discussion

Selected References

None.

Lower Taxa