Mentzelia obscura |
Mentzelia polita |
|
---|---|---|
Pacific blazing star |
elegant blazing star, polished blazing star |
|
Habit | Plants candelabra-form, 8–45 cm. | Plants perennial, bushlike, with subterranean caudices. |
Stems | multiple, erect, zigzag or straight; branches along entire stem, distal longest, antrorse, straight to upcurved; glabrescent, smooth to touch. |
|
Leaves | blade 16–84 × 2.2–10.6 mm, widest intersinus distance 2.2–7 mm; proximal oblanceolate, margins usually entire, occasionally dentate, teeth 0–6(–14), perpendicular to leaf axis, 1–2 mm; distal elliptic, lanceolate, or linear, base not clasping, margins usually entire, rarely dentate, teeth 0(–6), perpendicular to leaf axis, 0.6–2 mm; abaxial surface with complex grappling-hook and infrequently needlelike trichomes, adaxial surface with needlelike trichomes. |
|
Basal leaves | persisting; petiole present or absent; blade linear-lanceolate to linear, margins usually irregularly deeply lobed, lobes pointed. |
|
Cauline leaves | petiole absent; blade ovate-lanceolate to linear, to 15(–22) cm, margins few-lobed or entire. |
|
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 light to golden yellow, 7.8–11(–14.2) × 1.9–2.8(–4.2) mm, apex rounded, glabrous abaxially; stamens white to light yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 5.9–9.2(–10.1) × 1.2–2.7 mm, with anthers, second whorl with anthers; anthers twisted after dehiscence, epidermis smooth; styles 5.2–7.6 mm. |
Capsules | clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
cup-shaped, 4.5–8.8 × 5.8–8.8 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 15–24 per cell. |
2n | = 36. |
= 22. |
Mentzelia obscura |
Mentzelia polita |
|
Phenology | Flowering Feb–May. | Flowering Apr–Aug. |
Habitat | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. | Dry washes, arroyos, steep slopes. |
Elevation | 200–1700 m. (700–5600 ft.) | 500–1500 m. (1600–4900 ft.) |
Distribution |
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
|
CA; NV |
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 polita is known only from the Clark Mountains of San Bernardino County, California, and the Spring Mountains of Clark County, Nevada. (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) | A. Nelson: Bot. Gaz. 47: 427. (1909) |
Web links |