Mentzelia obscura |
Mentzelia uintahensis |
|
---|---|---|
Pacific blazing star |
Uintah blazingstar |
|
Habit | Plants candelabra-form, 8–45 cm. | Plants perennial, bushlike, with subterranean caudices or rhizomes. |
Stems | multiple, erect, zigzag or straight; branches distal or along entire stem, distal longest or all ± equal, antrorse, upcurved; hairy. |
|
Leaves | blade 17–56 × 5.8–28 mm, widest intersinus distance 1–4.9(–6) mm; proximal oblanceolate to elliptic, margins pinnate to pinnatisect, lobes 4–12, antrorse, 1.9–7.7 mm; distal elliptic to lanceolate, base not clasping, margins pinnate to pinnatisect, lobes 4–12, antrorse, 2.6–13.3 mm; abaxial surface with simple grappling-hook and occasionally complex grappling-hook and needlelike trichomes, adaxial surface with simple grappling-hook and 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 golden yellow, 8.5–15.2 × 3.8–7.9 mm, apex acute to rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments broadly spatulate, strongly clawed, 5–10.4 × 2.8–6 mm, with anthers, second whorl with anthers; anthers usually twisted after dehiscence, epidermis smooth; styles 5.8–8.5 mm. |
Capsules | clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
cup-shaped, 4.2–8.8 × 3.6–5.8 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 4–7 per cell. |
2n | = 36. |
= 22. |
Mentzelia obscura |
Mentzelia uintahensis |
|
Phenology | Flowering Feb–May. | Flowering May–Sep. |
Habitat | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. | Sparsely vegetated steep talus slopes and roadcuts. |
Elevation | 200–1700 m. (700–5600 ft.) | 1500–2800 m. (4900–9200 ft.) |
Distribution |
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
|
CO; UT |
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 uintahensis is known from northwestern Colorado (Rio Blanco, Mesa, and Moffat counties) and northeastern Utah (Carbon, Duchesne, and Uintah counties). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 540. | FNA vol. 12, p. 510. |
Parent taxa | Loasaceae > Mentzelia > sect. Trachyphytum | Loasaceae > Mentzelia > sect. Bartonia |
Sibling taxa | ||
Synonyms | M. multicaulis var. uintahensis | |
Name authority | H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) | (N. H. Holmgren & P. K. Holmgren) J. J. Schenk & L. Hufford: Novon 19: 120. (2009) |
Web links |