Mentzelia multiflora
Mentzelia involucrata
Adonis blazingstar, Adonis stickleaf, desert stickleaf, many-flower western star
sand blazing star, white-bract blazing star
solitary, erect, straight;
branches distal, distal longest, antrorse, upcurved; hairy.
blade 35.9–125(–146) × 2.2–26.2 mm, widest intersinus distance 2.1–11.9(–14) mm, always on some leaves 4+ mm;
proximal oblanceolate, lanceolate, or elliptic, margins pinnate, lobes 14–30, slightly antrorse or perpendicular to leaf axis, 1.5–4.6(–8.9) mm;
distal lanceolate, base not clasping, margins pinnate, lobes 10–26, slightly antrorse or perpendicular to leaf axis, 1.3–9.5 mm;
abaxial surface with simple grappling-hook, complex grappling-hook, and generally needlelike trichomes, adaxial surface with simple grappling-hook or needlelike trichomes.
petioles present or absent;
blade lanceolate, to 10(–16) cm;
margins shallowly to deeply lobed, lobes acute.
petioles absent;
blade ovate to lanceolate, to 10(–16) cm, base often cordate-clasping, margins deeply to shallowly lobed, lobes acute.
margins entire or toothed to pinnate.
white with green margins, conspicuous, concealing pedicel, ovary, and capsule.
petals light to golden yellow, (11.4–)13.8–24.4(–26.9) × 4–7.5 mm, apex rounded, glabrous abaxially;
stamens light to golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, (10.6–)12–21.7 × 2.1–5.1 mm, without anthers, second whorl with anthers;
anthers straight after dehiscence, epidermis smooth;
styles 7.7–15.8 mm.
petals white to pale yellow, usually with orange veins, obovate, 13–65 mm, apex mucronate;
stamens 4–26 mm, less than 1/2 petal length, all fertile, none petaloid (flowers appearing to have 5 petals);
filaments ± monomorphic, linear, distally 2-lobed, lobes 0.5–2 mm;
anther stalk shorter or longer than filament lobes;
style 8–30 mm.
cylindric, 11.2–24.7 × 5.6–8.7 mm, base tapering to rounded, not longitudinally ridged.
cylindric to cup-shaped, 14–25(–30) × 5–10 mm, erect.
coat anticlinal cell walls sinuous, papillae 34–48 per cell.
usually constricted proximal to middle;
seed coat anticlinal cell walls wavy.
= 18.
= 18.
Mentzelia multiflora
Mentzelia involucrata
Mentzelia multiflora has been considered one of the most widespread species in sect. Bartonia, a result of treating the species as a "garbage bin" for populations that lack features characteristic of more specialized species. The phylogenetic study by J. J. Schenk and L. Hufford (2011) showed that populations consistent with the type of M. multiflora are centered in the southern Rocky Mountains, especially along their eastern front, and the species notably does not occur in Arizona, California, Nevada, or Utah, in which it regularly has been described in regional floras. In the intermountain region, many specimens previously determined as M. multiflora are M. longiloba. In southeastern New Mexico and Texas, many specimens previously determined as M. multiflora are likely to be M. procera or M. longiloba var. chihuahuaensis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Mentzelia involucrata is easily distinguished from other species in sect. Bicuspidaria by its large white bracts, which are strikingly similar to those of M. congesta in sect. Trachyphytum. Phylogenetic studies show that these species are not closely related, suggesting a homoplasious origin of the characteristic (J. M. Brokaw and L. Hufford, 2010). Populations exhibiting petals longer than 3 cm have previously been called var. megalantha. However, a study by G. S. Daniels (1970) suggested that insufficient geographic and morphological discontinuities exist for recognition of varieties.
P. A. Munz (1974) mistakenly cited var. megalantha as Mentzelia involucrata subsp. megalantha I. M. Johnston, a name never validly published.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
SW CO Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
CA
