Mentzelia obscura |
Mentzelia longiloba |
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Pacific blazing star |
Adonis blazingstar, Adonis stickleaf, many flower mentzelia |
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Habit | Plants candelabra-form, 8–45 cm. | Plants biennial or perennial, bushlike or candelabra-form, perennials with ground-level caudices. | ||||||||
Stems | solitary, erect, straight; branches distal or along entire stem, distal or proximal longest, antrorse, upcurved; hairy. |
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Leaves | blade 35–112 × 4.3–27.1 mm, widest intersinus distance 2.3–15.3 mm, always on some leaves 4+ mm; proximal oblanceolate to elliptic, margins dentate to pinnate, teeth or lobes 12–30(–50), perpendicular to leaf axis or antrorse, 1–9 mm; distal lanceolate, base not clasping, margins serrate to pinnate, teeth or lobes 8–28, perpendicular to slightly antrorse, 0.8–7.5 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and generally needlelike 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 usually irregularly deeply lobed, lobes pointed. |
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Cauline leaves | petiole absent; blade ovate-lanceolate to linear, to 15(–22) cm, margins few-lobed or entire. |
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Bracts | green, ovate to ovate-lanceolate, 2.9–8.2 × 1.1–1.9 mm, width 1/8–1/2 length, not concealing capsule, margins entire. |
margins entire or toothed to pinnate. |
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Flowers | sepals 2–6 mm; petals yellow to orange proximally, yellow distally, 3–8 mm, apex rounded or acute apex; stamens 20–40, 2–7 mm, filaments monomorphic, filiform, unlobed; styles 2–6 mm. |
petals golden yellow, 11.3–20.4 × 2.9–7.2[–8.9] mm, apex acute to rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 10.4–17.8 × 1.9–5.2[–5.6] mm, with or without anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles (5.4–)8.5–10.9(–13) mm. |
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Capsules | clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
cup-shaped to cylindric, [7.6–]9.1–16.4 × 5.7–9.2 mm, length usually to 2 times diam., sometimes a few more, base tapering to rounded, not longitudinally ridged. |
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Seeds | 15–50, in 2+ rows distal to mid fruit, tan, usually not, occasionally sparsely, dark-mottled, usually irregularly polygonal, occasionally triangular prisms proximal to mid fruit, surface colliculate under 10x magnification; recurved flap over hilum absent; seed coat cell outer periclinal wall domed, domes on seed edges less than 1/2 as tall as wide at maturity. |
coat anticlinal cell walls straight or sinuous, papillae 4–106 per cell. |
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2n | = 36. |
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Mentzelia obscura |
Mentzelia longiloba |
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Phenology | Flowering Feb–May. | |||||||||
Habitat | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. | |||||||||
Elevation | 200–1700 m. (700–5600 ft.) | |||||||||
Distribution |
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
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AZ; CA; CO; NM; TX; UT; n Mexico
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Discussion | Mentzelia obscura is morphologically intermediate to M. desertorum and M. albicaulis and is known to occur in mixed populations with both species. Reliable discrimination among these species usually requires mature seeds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 4 (3 in the flora). Variety pinacatensis J. J. Schenk & L. Hufford is known from the Mexican state of Sonora. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 540. | FNA vol. 12, p. 520. | ||||||||
Parent taxa | Loasaceae > Mentzelia > sect. Trachyphytum | Loasaceae > Mentzelia > sect. Bartonia | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | M. multiflora subsp. longiloba | |||||||||
Name authority | H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) | J. Darlington: Ann. Missouri Bot. Gard. 21: 176. (1934) | ||||||||
Web links |