Mentzelia obscura |
Mentzelia todiltoensis |
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Pacific blazing star |
Jemez Mountains blazingstar |
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Habit | Plants candelabra-form, 8–45 cm. | Plants biennial or perennial, bushlike, with ground-level caudices. |
Stems | solitary or multiple, erect, straight; branches distal, distal longest, antrorse, straight; hairy. |
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Leaves | blade 41–121 × 1.5–40 mm, widest intersinus distance 1.1–3.3 mm; proximal oblanceolate, elliptic, or linear, margins entire or serrate to pinnatisect, teeth or lobes 0–26, slightly antrorse, (0.9–)2.4–18.6 mm; distal oblanceolate, elliptic, lanceolate, or linear, base not clasping, margins entire, serrate, or pinnatisect, teeth or lobes 0–22, slightly antrorse, 0.8–18 mm; abaxial surface with needlelike and occasionally simple grappling-hook and/or complex grappling-hook trichomes, adaxial surface with 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 pinnate. |
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 light to golden yellow, (10.4–)11.7–24.6 × 1.8–5.1 mm, apex acute to rounded, glabrous abaxially; stamens light to golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 10–21 × 1.4–4 mm, without anthers, second whorl with anthers; anthers twisted or occasionally straight after dehiscence, epidermis papillate; styles 5.5–12.7 mm. |
Capsules | clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
cup-shaped to cylindric, 6.7–20.2 × 4.5–8.5 mm, base tapering or 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 sinuous, papillae 6–12 per cell. |
2n | = 36. |
= 20. |
Mentzelia obscura |
Mentzelia todiltoensis |
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Phenology | Flowering Feb–May. | Flowering Jul–Oct. |
Habitat | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. | Hillside slopes, hilltops, hard gypsum-rich clayey soils. |
Elevation | 200–1700 m. (700–5600 ft.) | 1600–2200 m. (5200–7200 ft.) |
Distribution |
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
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NM |
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 todiltoensis occurs in northcentral New Mexico. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 540. | FNA vol. 12, p. 508. |
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. D. Atwood & S. L. Welsh: W. N. Amer. Naturalist 65: 365, fig. 1. (2005) |
Web links |