Mentzelia nuda
Mentzelia dispersa
bractless blazingstar, goodmother, naked blazingstar or western star, stickleaf mentzelia
bushy blazing-star, bushy mentzelia, Nada stickleaf, Nevada blazingstar, scattered blazing star
solitary (or multiple as wound response), erect, straight;
branches distal, distal longest, antrorse, straight; hairy.
blade 37–120 × 5–24.4 mm, widest intersinus distance 4.8–19.6 mm;
proximal oblanceolate to elliptic, margins serrate, teeth 14–30, slightly antrorse, 0.6–4.9 mm;
distal elliptic to lanceolate, base not clasping, margins serrate, teeth 12–30, slightly antrorse, 0.7–4.7 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 elliptic to linear, margins usually dentate, sinuses extending less than 1/4 to midvein, 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.
margins pinnate.
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.
petals white, 22.6–49 × 3.6–10.3 mm, apex acute, glabrous abaxially, stamens white, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 20–47 × 3–10.2 mm, without anthers, second whorl without anthers;
anthers straight after dehiscence, epidermis smooth;
styles 11.5–18.5 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.
cylindric, 14.5–29 × 6.9–12.3 mm, base tapering or rounded, not longitudinally ridged.
narrow-cylindric, 7–30 × 1–2.5 mm, axillary curved to 30° at maturity, usually inconspicuously longitudinally ribbed.
coat anticlinal cell walls wavy, papillae 4–8 per cell.
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.
= 20.
= 18, 36, 72.
Mentzelia nuda
Mentzelia dispersa
Mentzelia nuda is morphologically similar to, and phylogenetically near, M. strictissima (J. J. Schenk 2009), but it can be distinguished from the latter by its much larger flowers and capsules. The two species have adjacent ranges in New Mexico and Texas but do not overlap despite apparently similar habitat requirements. Mentzelia strictissima occurs west and south of M. nuda and abuts against the southernmost portion of the Rocky Mountains. In the northern portion of its range, M. nuda too approaches the foothills of the southern Rocky Mountains and extends eastward into the plains. Mentzelia nuda was collected once in northeastern Illinois in 1901 but apparently did not become established there. Reports of M. nuda from Arizona are based on misidentified material of M. laevicaulis and M. rusbyi.
(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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