Mentzelia monoensis

Plants candelabra-form, 10–30 cm. Basal leaves persisting; petiole present or absent; blade linear-lanceolate to linear, margins usually moderately to shallowly lobed, rarely entire. Cauline leaves: petiole present or absent (proximal leaves), absent (distal leaves); blade linear-lanceolate to linear (proximal leaves), ovate to linear (distal leaves), to 13 cm, margins usually moderately to shallowly lobed, rarely entire. Bracts green, sometimes with white base, ovate, 3–4.1 × 1.1–1.7 mm, width 1/4–1/2 length, not concealing capsule, margins entire. Flowers: sepals 2–3 mm; petals orange proximally, yellow distally, 2–4 mm, apex retuse or rounded; stamens 10–30, 2–3 mm, filaments monomorphic, filiform, unlobed; styles 2–3 mm. Capsules cylindric or clavate, 6–15 × 2–3 mm, axillary curved to 20° at maturity, usually inconspicuously longitudinally ribbed. Seeds 15–30, in 2+ rows distal to mid fruit, tan, not dark-mottled, usually irregularly polygonal, occasionally triangular prisms proximal to mid fruit, surface colliculate under 10× magnification; recurved flap over hilum absent; seed-coat cell outer periclinal wall domed, domes on seed edges less than 1/2 as tall as wide at maturity. 2n = 54.

Phenology: Flowering May–Aug.
Habitat: Coarse pumice soils on open slopes, sagebrush or bitterbrush scrub, pine forests.
Elevation: 2000–2500 m.

Calif.

Discussion

Mentzelia monoensis is narrowly distributed predominantly south of Mono Lake and north of Lake Crowley in Mono County, California, and is most commonly found in soils derived from the eruptions of the Mono Craters (J. M. Brokaw et al. 2015). Phylogenetic studies suggest that this hexaploid is the only allopolyploid derived from representatives of both the “Affines” and “Trachyphyta” clades (Brokaw and L. Hufford 2010b). Mentzelia monoensis is morphologically similar to sympatric populations of M. montana. However, the bracts of M. monoensis are more often unlobed and green throughout. Furthermore, seeds of M. monoensis have tan, unmottled coats that are always composed of cells that are rounded, appearing as shallow domes. In contrast, seeds of M. montana have mottled coats with cells that stand out as rough, pointed knobs along the seed edges.

Selected References

None.

Lower Taxa