Mentzelia nitens
Mentzelia holmgreniorum
shining blazing star, Venus blazingstar
Holmgrens' blazingstar
solitary, erect, straight;
branches distal or along entire stem, distal or proximal longest, antrorse, upcurved; hairy.
blade 42–89 × 11–31.9 mm, widest intersinus distance 2.3–3.6 mm;
proximal oblanceolate to elliptic, margins pinnatisect, lobes 14–20, strongly antrorse, 4.9–14.4 mm;
distal lanceolate, base not clasping, margins pinnatisect, lobes 12–18, strongly antrorse, 4.2–12.4 mm;
abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, adaxial surface with simple grappling-hook and needlelike trichomes.
persisting;
petiole present or absent;
blade lanceolate to linear, margins usually deeply to shallowly lobed, rarely entire.
petiole absent;
blade ovate-lanceolate to linear, to 15 cm, margins deeply to shallowly lobed or entire.
green, lanceolate, 4.5–8.3 × 1.2–3.6 mm, width 1/5–1/2 length, not concealing capsule, margins entire.
margins pinnate.
sepals 3–8 mm;
petals yellow to orange proximally, yellow distally, (7–)8–18 mm, apex rounded or acute apex;
stamens 20+, 3–8 mm, filaments monomorphic, filiform, unlobed;
styles 4–8 mm.
petals golden yellow, 13.5–18.8 × 5.2–6.6 mm, apex rounded, glabrous abaxially;
stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 11.1–16 × 2.7–5 mm, without anthers, second whorl with anthers;
anthers straight after dehiscence, epidermis smooth;
styles 8.4–10.6 mm.
clavate, 13–26 × 2–3.5 mm, axillary curved to 180° at maturity, usually inconspicuously longitudinally ribbed.
cylindric, 13.1–14.6 × 5.8–6.9 mm, base tapering, not longitudinally ridged.
15–40, in 2+ rows distal to mid fruit, tan, usually dark-mottled, usually irregularly polygonal, occasionally triangular prisms proximal to mid fruit, surface colliculate under 10x magnification; recurved flap over hilum usually present;
seed coat cell outer periclinal wall domed, domes on seed edges less than 1/2 as tall as wide at maturity.
coat anticlinal cell walls sinuous, papillae 26–51 per cell.
= 18.
= 20.
Mentzelia nitens
Mentzelia holmgreniorum
Mentzelia nitens is similar to both M. eremophila and M. jonesii but exhibits little distributional overlap with either species. See 71. M. eremophila and 73. M. jonesii for discussion of similarities. Reports of M. nitens from Arizona are based on specimens treated here as M. jonesii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Mentzelia holmgreniorum is known from Apache, Coconino, and Navajo counties, Arizona, and Catron County, New Mexico. It is allopatric from the species most similar to it (M. filifolia, M. laciniata, and M. lagarosa), occurring south and west of all three; it differs from all these species in having upcurved rather than straight branches, and from M. filifolia and M. laciniata in having both simple grappling-hook and needlelike trichomes (versus only needlelike trichomes) on its adaxial leaf surfaces. In addition, M. holmgreniorum differs from M. filifolia in having leaf blades with greater intersinus distances (2.3–3.6 mm versus 1–2.4 mm) and wider lobes (1.6–2.5 mm versus 0.8–1.4 mm), from M. laciniata in having pinnate bracts (versus usually entire, rarely pinnate), and from M. lagarosa in having leaf blade lobes that are strongly antrorsely oriented (versus slightly antrorsely or perpendicular to the leaf axis) and flowers with larger petals (13.5–18.8 × 5.2–6.6 mm versus 8.3–13 × 2.2–5.4 mm) and longer outermost stamens (11.1–16 mm versus 6.5–10.7 mm).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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