Mentzelia affinis
Mentzelia dispersa
yellow comet
bushy blazing-star, bushy mentzelia, Nada stickleaf, Nevada blazingstar, scattered blazing star
persisting;
petiole present or absent;
blade linear-lanceolate to linear, margins usually deeply to moderately lobed, sinuses extending 1/4+ to midvein, rarely entire.
persisting;
petiole present or absent;
blade elliptic to linear, margins usually dentate, sinuses extending less than 1/4 to midvein, or entire, rarely deeply lobed.
petiole absent;
blade ovate-lanceolate to lanceolate, to 17 cm, margins usually dentate or entire, rarely deeply lobed.
petiole present or absent (proximal leaves), absent (distal leaves);
blade elliptic to linear (proximal leaves), orbiculate to linear (distal leaves), to 10 cm, margins usually dentate, sinuses extending less than 1/4 to midvein, or entire, rarely deeply lobed.
green, ovate to lanceolate, 2.7–6.6 × 0.9–2.1 mm, width 1/5–1/3 length, not concealing capsule, margins 3-lobed or entire.
green, orbiculate to ovate, 2.1–6.5 × 1.1–3 mm, width 1/3–7/8 length, not concealing capsule, margins 3-lobed or entire.
sepals 1–7 mm;
petals yellow to orange proximally, yellow distally, 4–12 mm, apex acute;
stamens 20+, 3–6.5 mm, filaments monomorphic, filiform, unlobed;
styles 3–6.5 mm.
sepals 1–3.5 mm;
petals usually yellow, rarely orange, proximally, yellow distally, 2–6(–8) mm, apex rounded;
stamens 20–40, 2–4.5 mm, filaments monomorphic, filiform, unlobed;
styles 2–3.5(–5) mm.
narrowly cylindric, 7–32 × 1–3 mm, axillary curved to 90° at maturity, often prominently longitudinally ribbed.
narrow-cylindric, 7–30 × 1–2.5 mm, axillary curved to 30° at maturity, usually inconspicuously longitudinally ribbed.
10–20, in 1 row distal to mid fruit, tan, dark-mottled or not, triangular prisms, surface ±smooth under 10x magnification; recurved flap over hilum absent;
seed coat cell outer periclinal wall flat.
10–20, in 1 row distal to mid fruit, tan, dark-mottled or not, triangular prisms, surface ± smooth under 10x magnification; recurved flap over hilum absent;
seed coat cell outer periclinal wall flat.
= 18.
= 18, 36, 72.
Mentzelia affinis
Mentzelia dispersa
Herbarium specimens of Mentzelia affinis are often difficult to distinguish from those of M. dispersa despite distinct evolutionary histories (J. M. Brokaw and L. Hufford 2010). Several characters, including flower size, leaf margins, and capsule surfaces, differ substantially between these species, but habitat is the most dependable diagnostic character. Verified populations of M. affinis have not been found above 1200 meters in desert habitats, and grassland populations are usually restricted to much lower elevations. Sympatric populations of M. affinis and M. dispersa have not been found, and, in areas of range overlap in southern California, M. dispersa has not been found below 1200 meters or in desert vegetation.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Mentzelia dispersa is the only polyploid species solely derived from the “Affines” clade and may be an autopolyploid complex (J. M. Brokaw and L. Hufford 2010, 2010b). Morphological characters that consistently distinguish cytotypes within M. dispersa have not been found. Mentzelia dispersa is most easily confused with M. affinis (see discussion under 65. M. affinis) but is phylogenetically distinct (Brokaw and Hufford 2010, 2010b).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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