Mentzelia humilis
Mentzelia sivinskii
gypsum blazingstar
Sivinski's blazingstar
solitary or multiple, erect, straight;
branches distal or along entire stem, distal longest or all ± equal, antrorse; straight to upcurved; hairy.
solitary, erect, straight;
branches distal or along entire stem, distal or proximal longest, antrorse, straight; 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.
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.
margins usually entire, rarely pinnate.
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.
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.
cup-shaped, 5.3–10.2 × (4.2–)5.2–8.6 mm, base rounded, not longitudinally ridged.
cup-shaped, 8.2–12.7 × 5.1–7.7 mm, base tapering to rounded, not longitudinally ridged.
coat anticlinal cell walls wavy, papillae 6–12 per cell.
coat anticlinal cell walls sinuous, papillae 12–21 per cell.
= 18.
Mentzelia humilis
Mentzelia sivinskii
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 sivinskii is known from La Plata County, Colorado, and Rio Arriba and San Juan counties, New Mexico.
(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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