Mentzelia humilis
Mentzelia torreyi
gypsum blazingstar
Torrey's blazing star
solitary or multiple, erect, straight;
branches distal or along entire stem, distal longest or all ± equal, antrorse; straight to upcurved; hairy.
5–25 cm.
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.
petiole absent;
blade ovate or obovate, to 45 × 35 mm, intersinus distance 2–4 mm.
margins usually entire, rarely pinnate.
0(–1.5) mm.
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.
petals yellow to orange, narrowly spatulate to obovate, 4.5–17 × 1.2–5 mm, apex rounded;
stamens 25–45, 7–21 mm;
styles 7–18 mm.
cup-shaped, 5.3–10.2 × (4.2–)5.2–8.6 mm, base rounded, not longitudinally ridged.
3–7 × 3–4.5 mm.
coat anticlinal cell walls wavy, papillae 6–12 per cell.
3–9 per capsule, edges prominently to inconspicuously ridged.
= 28.
Mentzelia humilis
Mentzelia torreyi
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.)
Varieties 2 (2 in flora).
In the phylogenetic study by L. Hufford et al. (2003), Mentzelia torreyi was recovered as the sister to the rest of the genus.
(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 |
1. Petals 8–17 mm, yellow; longest stamens to 1 mm longer than petals. | var. torreyi |
1. Petals 4.5–8 mm, orangish yellow, orange, or burnt orange; longest stamens usually much more than 1 mm longer than petals. | var. acerosa |
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