Mentzelia nuda
Mentzelia micrantha
bractless blazingstar, goodmother, naked blazingstar or western star, stickleaf mentzelia
San Luis blazingstar, San Luis or chaparral blazingstar, San Luis stick leaf, small flower stickleaf
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 lanceolate to linear, margins irregularly deeply lobed to dentate.
petiole present or absent (proximal leaves), absent (distal leaves);
blade lanceolate to linear (proximal leaves), orbiculate to lanceolate (distal leaves), to 18 cm, margins irregularly deeply lobed to dentate proximally, dentate or entire distally.
margins pinnate.
green, orbiculate to ovate, 3.4–6.6 × 2.5–5.9 mm, width 3/4 to ± equal length, often concealing capsule, margins sinuate 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 mm;
petals yellow, 2-5 mm, apex acute;
stamens 10–20, 1.5–4 mm, filaments heteromorphic, 5 outermost elliptic, distally 2-lobed, inner filiform, unlobed;
styles 2–3(–5) mm.
cylindric, 14.5–29 × 6.9–12.3 mm, base tapering or rounded, not longitudinally ridged.
cylindric, 6–13 × 1.5–2.5 mm, axillary curved to 20° at maturity, usually inconspicuously, occasionally prominently, longitudinally ribbed.
coat anticlinal cell walls wavy, papillae 4–8 per cell.
4–10, in 1 row distal to mid fruit, dark brown or tan, dark-mottled, triangular prisms, surface ±smooth to minutely tessellate under 10x magnification; recurved flap over hilum absent;
seed coat cell outer periclinal wall flat.
= 20.
= 18.
Mentzelia nuda
Mentzelia micrantha
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 micrantha is easily distinguished from other species in sect. Trachyphytum by the presence of two lateral lobes on the filaments of the five outermost stamens. This characteristic is distinct from the filament lobes of some species in sect. Bicuspidaria, which occur on all or most stamens. Phylogenetic studies have found that M. micrantha is not closely related to species in sect. Bicuspidaria (L. Hufford et al. 2003; J. M. Brokaw and Hufford 2010).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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