Mentzelia obscura |
Mentzelia memorabilis |
|
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Pacific blazing star |
nine-eleven blazingstar, september 11 stickleaf |
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Habit | Plants candelabra-form, 8–45 cm. | Plants perennial, bushlike, with subterranean caudices. |
Stems | multiple, erect, straight; branches distal, distal longest, antrorse, straight; hairy. |
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Leaves | blade 17–36.6 × 1.1–4.8 mm, widest intersinus distance 1.1–4.8 mm; proximal linear to oblanceolate, margins entire; distal linear, base not clasping, margins entire; abaxial surface with simple grappling-hook, complex grappling-hook, and 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. |
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, 7.4–11 × 2.6–3.4 mm, apex rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 5.5–9.1 × 1.4–2.7 mm, with anthers, second whorl with anthers; anthers twisted or straight after dehiscence, epidermis smooth; styles 4.8–8 mm. |
Capsules | clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
cup-shaped, 3.6–5.3 × 3.1–4.2 mm, base 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 6–10 per cell. |
2n | = 36. |
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Mentzelia obscura |
Mentzelia memorabilis |
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Phenology | Flowering Feb–May. | Flowering Jun–Sep. |
Habitat | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. | Barren gypsum-clay outcrops and hilltops. |
Elevation | 200–1700 m. (700–5600 ft.) | 1400–1700 m. (4600–5600 ft.) |
Distribution |
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
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AZ |
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 memorabilis occurs on the Uinkaret Plateau in Mohave County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 540. | FNA vol. 12, p. 512. |
Parent taxa | Loasaceae > Mentzelia > sect. Trachyphytum | Loasaceae > Mentzelia > sect. Bartonia |
Sibling taxa | ||
Name authority | H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) | N. H. Holmgren & P. K. Holmgren: Syst. Bot. 27: 753, fig. 4. (2002) — (as memorabalis) |
Web links |