Mentzelia humilis |
Mentzelia paradoxensis |
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gypsum blazingstar |
Paradox Valley blazingstar |
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Habit | Plants perennial, bushlike, with ground-level caudices. | Plants biennial, usually cylindric, rarely candelabra-form. | ||||
Stems | solitary or multiple, erect, straight; branches distal or along entire stem, distal longest or all ± equal, antrorse; straight to upcurved; hairy. |
solitary, erect, straight; branches distal or along entire stem, ± equal, perpendicular to stem, especially proximal and mid-stem, or slightly antrorse, especially distal, straight; 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. |
blade 38.1–95 × 6–17(–26) mm, widest intersinus distance 1.6–4.7 mm; proximal oblanceolate, lanceolate, or elliptic, margins dentate to serrate or pinnate, teeth or lobes 10–22, slightly antrorse or perpendicular to leaf axis, 2–6.8 mm; distal elliptic to lanceolate, base not clasping, margins dentate to serrate or pinnate, teeth or lobes 8–16, slightly antrorse or perpendicular to leaf axis, 2.4–8.5 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, adaxial surface with needlelike and occasionally simple grappling-hook trichomes. |
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Bracts | margins usually entire, rarely pinnate. |
margins entire. |
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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. |
petals golden yellow, 8.3–14.5(–17.2) × 1.7–5.3 mm, apex acute to rounded, hairy abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 4.9–12.5 × 1.2–3.8 mm, with or without anthers, second whorl with anthers; anthers occasionally twisted or straight after dehiscence, epidermis papillate or not; styles 5.4–10.4 mm. |
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Capsules | cup-shaped, 5.3–10.2 × (4.2–)5.2–8.6 mm, base rounded, not longitudinally ridged. |
cup-shaped, 5–9 × 3.7–6.5 mm, base rounded, not longitudinally ridged. |
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Seeds | coat anticlinal cell walls wavy, papillae 6–12 per cell. |
coat anticlinal cell walls straight to slightly wavy, papillae 6–11 per cell. |
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2n | = 20. |
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Mentzelia humilis |
Mentzelia paradoxensis |
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Phenology | Flowering Jun–Sep. | |||||
Habitat | Sparsely vegetated gypsum knolls. | |||||
Elevation | 1500–2000 m. (4900–6600 ft.) | |||||
Distribution |
NM; TX
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CO |
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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 paradoxensis is known only from white gypsum hills in Paradox Valley, Montrose County. (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. 505. | ||||
Parent taxa | Loasaceae > Mentzelia > sect. Bartonia | Loasaceae > Mentzelia > sect. Bartonia | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | M. pumila var. humilis, Nuttallia humilis, Touterea humilis | |||||
Name authority | (Urban & Gilg) J. Darlington: Ann. Missouri Bot. Gard. 21: 155. (1934) | J. J. Schenk & L. Hufford: Madroño 57: 249, fig. 2A. (2010) | ||||
Web links |