Mentzelia humilis |
Mentzelia eremophila |
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gypsum blazingstar |
pinyon blazing star, solitary blazing star |
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Habit | Plants perennial, bushlike, with ground-level caudices. | Plants candelabra-form, (7–)30–50(–60) cm. | ||||
Stems | solitary or multiple, erect, straight; branches distal or along entire stem, distal longest or all ± equal, antrorse; straight to upcurved; hairy. |
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Leaves | blade 25–95 × 5.5–28(–36.2) mm, widest intersinus distance 0.8–9.1 mm; proximal spatulate to oblanceolate or elliptic, margins pinnate to pinnatisect, lobes 4–16(–20), slightly antrorse or perpendicular to leaf axis, 2.3–11.8(–16.4) mm; distal elliptic, lanceolate, spatulate, or linear, base not clasping, margins entire or dentate to pinnatisect, teeth or lobes (0–)4–16, slightly antrorse or perpendicular to leaf axis, 2.3–13.8(–16.9) mm; abaxial surface with simple grappling-hook, needlelike, and sometimes complex grappling-hook trichomes, adaxial surface with simple grappling-hook and needlelike trichomes. |
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Basal leaves | persisting; petiole present or absent; blade linear-lanceolate to linear, margins very deeply lobed, lobes slender. |
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Cauline leaves | petiole absent; blade ovate-lanceolate to linear, to 15 cm, margins deeply to shallowly lobed or entire. |
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Bracts | margins usually entire, rarely pinnate. |
green, ovate to lanceolate, 4.8–12.4 × 0.9–3.5 mm, width 1/8–1/2 length, not concealing capsule, margins usually entire, rarely 2-lobed. |
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Flowers | petals white, 10.3–13(–28.6) × 1.4–4 mm, apex acute, glabrous abaxially; stamens white, 5 outermost petaloid, filaments linear to narrowly spatulate, slightly clawed, 8.8–19(–22.3) × 0.7–3.3 mm, without anthers, second whorl without anthers; anthers straight after dehiscence, epidermis papillate; styles 6.5–11.3 mm. |
sepals (7–)9–16 mm; petals yellow, 12–25 mm, apex acute or mucronate; stamens 20+, 3–10 mm, filaments monomorphic, filiform, unlobed; styles 7–15 mm. |
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Capsules | cup-shaped, 5.3–10.2 × (4.2–)5.2–8.6 mm, base rounded, not longitudinally ridged. |
clavate, 19–40 × 2–3.5 mm, axillary curved to 270° at maturity, usually inconspicuously longitudinally ribbed. |
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Seeds | coat anticlinal cell walls wavy, papillae 6–12 per cell. |
30–60, in 2+ rows distal to mid fruit, tan, usually dark-mottled, usually irregularly polygonal, occasionally triangular prisms proximal to mid fruit, surface colliculate under 10x magnification; recurved flap over hilum usually present; seed coat cell outer periclinal wall domed, domes on seed edges less than 1/2 as tall as wide at maturity. |
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2n | = 18. |
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Mentzelia humilis |
Mentzelia eremophila |
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Phenology | Flowering Mar–May. | |||||
Habitat | Rocky slopes, washes, canyons, creosote-bush scrub. | |||||
Elevation | 600–1300 m. (2000–4300 ft.) | |||||
Distribution |
NM; TX
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CA
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Discussion | Varieties 2 (2 in the flora). The basionym of Mentzelia humilis is often cited as M. multiflora var. humilis A. Gray (1852). However, in that publication Gray indicated accepted names in Roman capitals (see ipni.org), whereas the varietal name is in lower case, indicating that he was using it as a descriptive term rather than a scientific name. Valid publication of the basionym thus must be attributed to Urban and Gilg. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Mentzelia eremophila is narrowly distributed in eastern Kern and northwestern San Bernardino counties. It is morphologically similar and closely related to M. nitens (J. M. Brokaw and L. Hufford 2010). However, M. eremophila generally has longer sepals, petals, and styles, and populations of M. nitens have not been found south of Inyo County in California. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 503. | FNA vol. 12, p. 537. | ||||
Parent taxa | Loasaceae > Mentzelia > sect. Bartonia | Loasaceae > Mentzelia > sect. Trachyphytum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | M. pumila var. humilis, Nuttallia humilis, Touterea humilis | M. lindleyi var. eremophila | ||||
Name authority | (Urban & Gilg) J. Darlington: Ann. Missouri Bot. Gard. 21: 155. (1934) | (Jepson) H. J. Thompson & J. E. Roberts: Phytologia 21: 281. (1971) | ||||
Web links |