Mentzelia humilis
Mentzelia monoensis
gypsum blazingstar
Mono craters blazing star
solitary or multiple, erect, straight;
branches distal or along entire stem, distal longest or all ± equal, antrorse; straight to upcurved; hairy.
blade 25–95 × 5.5–28(–36.2) mm, widest intersinus distance 0.8–9.1 mm;
proximal spatulate to oblanceolate or elliptic, margins pinnate to pinnatisect, lobes 4–16(–20), slightly antrorse or perpendicular to leaf axis, 2.3–11.8(–16.4) mm;
distal elliptic, lanceolate, spatulate, or linear, base not clasping, margins entire or dentate to pinnatisect, teeth or lobes (0–)4–16, slightly antrorse or perpendicular to leaf axis, 2.3–13.8(–16.9) mm;
abaxial surface with simple grappling-hook, needlelike, and sometimes complex grappling-hook trichomes, adaxial surface with simple grappling-hook and needlelike trichomes.
persisting;
petiole present or absent;
blade linear-lanceolate to linear, margins usually moderately to shallowly lobed, rarely entire.
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.
margins usually entire, rarely pinnate.
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.
petals white, 10.3–13(–28.6) × 1.4–4 mm, apex acute, glabrous abaxially;
stamens white, 5 outermost petaloid, filaments linear to narrowly spatulate, slightly clawed, 8.8–19(–22.3) × 0.7–3.3 mm, without anthers, second whorl without anthers;
anthers straight after dehiscence, epidermis papillate;
styles 6.5–11.3 mm.
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.
cup-shaped, 5.3–10.2 × (4.2–)5.2–8.6 mm, base rounded, not longitudinally ridged.
cylindric or clavate, 6–15 × 2–3 mm, axillary curved to 20° at maturity, usually inconspicuously longitudinally ribbed.
coat anticlinal cell walls wavy, papillae 6–12 per cell.
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 10x 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.
= 54.
Mentzelia humilis
Mentzelia monoensis
Varieties 2 (2 in the flora).
The basionym of Mentzelia humilis is often cited as M. multiflora var. humilis A. Gray (1852). However, in that publication Gray indicated accepted names in Roman capitals (see ipni.org), whereas the varietal name is in lower case, indicating that he was using it as a descriptive term rather than a scientific name. Valid publication of the basionym thus must be attributed to Urban and Gilg.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blade widest intersinus distances 0.8–2.6(–3.3) mm; lobes of proximal leaves 1–2.9 mm wide. | var. humilis |
1. Leaf blade widest intersinus distances 1.6–9.1 mm (always on some leaves greater than 2.6 mm); lobes of proximal leaves (1.1–)2.9–5.1 mm wide. | var. guadalupensis |
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USDA Plants Database
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