Mentzelia obscura |
Mentzelia multicaulis |
|
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Pacific blazing star |
manystem blazingstar, multiple-branch blazingstar |
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Habit | Plants candelabra-form, 8–45 cm. | Plants perennial, bushlike, with subterranean caudices or sometimes rhizomes. |
Stems | multiple, erect or decumbent, zigzag or straight; branches distal or along entire stem, distal longest or all ± equal, antrorse, straight to upcurved; hairy. |
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Leaves | blade 20–49(–57) × 4.2–19 mm, widest intersinus distance 1.1–5.3 mm; proximal oblanceolate to elliptic, margins pinnate to pinnatisect, lobes 4–10, slightly antrorse, 0.7–7.6 mm; distal linear to lanceolate, base not clasping, margins entire or pinnate, lobes 0–10, slightly antrorse, 1.9–7.8 mm; abaxial surface with simple grappling-hook trichomes, adaxial surface with 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. |
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, 10.6–17.9 × 5.1–9 mm, apex obtuse, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments oblanceolate, slightly clawed, 6.5–10.5 × 2–4.5 mm, with anthers, second whorl with anthers; anthers twisted or straight after dehiscence, epidermis smooth; styles 6–11.5 mm. |
Capsules | clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
cup-shaped to cylindric, 6–13.6 × 3.4–6 mm, base tapering to rounded, not longitudinally ridged. |
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, papillae 4–9 per cell. |
2n | = 36. |
= 22. |
Mentzelia obscura |
Mentzelia multicaulis |
|
Phenology | Flowering Feb–May. | Flowering Jun–Aug. |
Habitat | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. | Sparsely vegetated steep slopes, drainage gullies, roadcuts. |
Elevation | 200–1700 m. (700–5600 ft.) | 2000–2500 m. (6600–8200 ft.) |
Distribution |
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
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CO
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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.) |
Mentzelia multicaulis is known to occur in Eagle, Grand, and Summit counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 540. | FNA vol. 12, p. 511. |
Parent taxa | Loasaceae > Mentzelia > sect. Trachyphytum | Loasaceae > Mentzelia > sect. Bartonia |
Sibling taxa | ||
Synonyms | Touterea multicaulis | |
Name authority | H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) | (Osterhout) J. Darlington: Ann. Missouri Bot. Gard. 21: 156. (1934) |
Web links |