Mentzelia integra |
Mentzelia obscura |
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virgin blazingstar |
Pacific blazing star |
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Habit | Plants winter annual or biennial, candelabra-form. | Plants candelabra-form, 8–45 cm. |
Stems | solitary, erect, straight; branches distal or along entire stem, distal or proximal longest, antrorse, straight, proximal not decumbent; hairy or glabrescent. |
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Leaves | blade (23–)29–78.4 × 3–14.6 mm, widest intersinus distance 1.6–8.5 mm; proximal oblanceolate or elliptic, margins dentate to serrate, teeth 4–12, proximal sides slightly antrorse, distal sides perpendicular to leaf axis, 0.8–5.3 mm; distal oblanceolate, elliptic, lanceolate, or linear, base not clasping, tapered, margins usually dentate to serrate, rarely entire, teeth (0–)2–10, proximal sides antrorse, distal sides perpendicular to leaf axis, 0.4–5.3 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, largest trichomes with pearly white bases, 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 | margins entire. |
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. |
Flowers | petals golden yellow, 8.6–13.9(–17.4) × 2.9–4.7(–6.1) mm, apex rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 6.7–13.2(–15.4) × 1.7–4.3 mm, usually without, rarely with, anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles 4.8–11.3 mm. |
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. |
Capsules | cup-shaped, 6.2–11.4(–13) × 6–8.4 mm, base rounded, not longitudinally ridged. |
clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
Seeds | coat anticlinal cell walls wavy, papillae 5–13 per cell. |
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. |
2n | = 20. |
= 36. |
Mentzelia integra |
Mentzelia obscura |
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Phenology | Flowering May–Sep. | Flowering Feb–May. |
Habitat | Roadsides, outcrops, hillsides, washes, dunes, sandy, gravelly, or volcanic soils. | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. |
Elevation | 800–1800 m. (2600–5900 ft.) | 200–1700 m. (700–5600 ft.) |
Distribution |
AZ; NV; UT
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AZ; CA; NV; UT; Mexico (Baja California, Sonora)
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Discussion | Mentzelia integra is found in northwestern Arizona, southeastern Nevada, and southwestern Utah. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 12, p. 521. | FNA vol. 12, p. 540. |
Parent taxa | Loasaceae > Mentzelia > sect. Bartonia | Loasaceae > Mentzelia > sect. Trachyphytum |
Sibling taxa | ||
Synonyms | M. multiflora var. integra, Nuttallia lobata | |
Name authority | (M. E. Jones) Tidestrom: Contr. U.S. Natl. Herb. 25: 363. (1925) | H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) |
Web links |