Mentzelia pectinata
Mentzelia tricuspis
San Joaquin blazing star
desert blazingstar, spiny-hair blazing star, spinyhair stickleaf, three point blazing star
persisting;
petiole present or absent;
blade lanceolate to linear, margins deeply to shallowly lobed.
petioles present;
blade lanceolate, to 12 cm;
margins shallowly lobed, lobes rounded.
petiole absent;
blade ovate to linear, to 12 cm, margins deeply lobed to dentate.
petioles usually present, rarely absent;
blade broadly ovate to lanceolate, to 12 cm, base not cordate-clasping, margins dentate to serrate.
green, ovate to lanceolate, 6.6–12.8 × 1.9–6.8 mm, width 1/5–2/3 length, not concealing capsule, margins 3–7-lobed.
green, inconspicuous, not concealing pedicel, ovary, or capsule.
sepals 3–13 mm;
petals red to orange proximally, orange to yellow distally, 8–22 mm, apex mucronate, rounded, or retuse;
stamens 20+, 4–11 mm, filaments monomorphic, filiform, unlobed;
styles 5–13 mm.
petals white to pale yellow, obovate, 10–30(–50) mm, apex mucronate;
stamens 7–17 mm, less than 1/2 petal length, all fertile, none petaloid (flowers appearing to have 5 petals);
filaments ± monomorphic, linear, distally 2-lobed, lobes 0.6–2.5 mm;
anther stalk usually shorter than filament lobes;
style 10–15 mm.
clavate, 12–35 × 2–4 mm, axillary curved to 90° at maturity, usually inconspicuously longitudinally ribbed.
cylindric to ovoid, 9–18(–23) × 5–8 mm, proximal nodding, distal erect.
20–40, in 2+ rows distal to mid fruit, tan, dark-mottled or not, usually irregularly polygonal, occasionally triangular prisms proximal to mid fruit, surface tuberculate under 10x magnification; recurved flap over hilum absent;
seed coat cell outer periclinal wall domed, domes on seed edges more than 1/2 as tall as wide at maturity.
constricted and grooved at middle;
seed coat anticlinal cell walls straight to slightly wavy, conspicuous.
= 18.
= 20.
Mentzelia pectinata
Mentzelia tricuspis
Mentzelia pectinata occurs in Kern, San Luis Obispo, Santa Barbara, and Tulare counties, around the southern rim of the San Joaquin Valley, extending into the Inner Coast Ranges and the southern foothills of the Sierra Nevada. Petal color varies from orange to yellow, and fully fertile artificial hybrids have been obtained between populations representing the extreme phenotypes (J. E. Zavortink 1966). Phylogenetic studies suggest that M. pectinata and M. congesta have hybridized to form several allopolyploid species (J. M. Brokaw and L. Hufford 2010b) despite their current allopatric distributions.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Mentzelia tricuspis is morphologically most similar to M. tridentata with differences largely limited to the lengths of the stamen filament lobes (and thus relative lengths of the anther stalks) and shapes of the seeds. However, the species are also distinct geographically, with M. tricuspis found in the southeastern Mojave Desert and northwestern Sonoran Desert and M. tridentata in the central to western Mojave Desert.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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