Mentzelia pectinata |
Mentzelia densa |
|
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San Joaquin blazing star |
Arkansas Canyon stickleaf, royal Gorge blazingstar |
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Habit | Plants candelabra-form, (8–)20–50(–60) cm. | Plants biennial, bushlike. |
Stems | solitary, decumbent to erect, straight; branches along entire stem, distal or proximal longest, antrorse, straight or upcurved, proximal decumbent; hairy. |
|
Leaves | blade 32–86 × 5.8–15 mm, widest intersinus distance 1.7–5.2(–7.1) mm; proximal oblanceolate to elliptic, margins dentate to pinnate, teeth or lobes 6–12, perpendicular to leaf axis, 1.2–6.3 mm; distal elliptic to lanceolate, base not clasping, margins dentate to pinnate, teeth or lobes 4–10, perpendicular to leaf axis, 1.8–5.2 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and occasionally needlelike trichomes, largest trichomes without pearly white bases, adaxial surface with simple grappling-hook and needlelike trichomes. |
|
Basal leaves | persisting; petiole present or absent; blade lanceolate to linear, margins deeply to shallowly lobed. |
|
Cauline leaves | petiole absent; blade ovate to linear, to 12 cm, margins deeply lobed to dentate. |
|
Bracts | green, ovate to lanceolate, 6.6–12.8 × 1.9–6.8 mm, width 1/5–2/3 length, not concealing capsule, margins 3–7-lobed. |
margins entire or toothed. |
Flowers | sepals 3–13 mm; petals red to orange proximally, orange to yellow distally, 8–22 mm, apex mucronate, rounded, or retuse; stamens 20+, 4–11 mm, filaments monomorphic, filiform, unlobed; styles 5–13 mm. |
petals golden yellow, 14.2–19.8 × 3.8–6.5 mm, apex acute to rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 12–18.1 × 2.7–4.8 mm, with or without anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles 8.3–11.1 mm. |
Capsules | clavate, 12–35 × 2–4 mm, axillary curved to 90° at maturity, usually inconspicuously longitudinally ribbed. |
cylindric, 12.2–18 × 4.3–8.3 mm, base tapering, not longitudinally ridged. |
Seeds | 20–40, in 2+ rows distal to mid fruit, tan, dark-mottled or not, usually irregularly polygonal, occasionally triangular prisms proximal to mid fruit, surface tuberculate under 10x magnification; recurved flap over hilum absent; seed coat cell outer periclinal wall domed, domes on seed edges more than 1/2 as tall as wide at maturity. |
coat anticlinal cell walls wavy, papillae 7–17 per cell. |
2n | = 18. |
= 20. |
Mentzelia pectinata |
Mentzelia densa |
|
Phenology | Flowering Mar–May. | Flowering Jun–Aug. |
Habitat | Slopes of sandy or gray-white silty soils, grasslands, oak savannas, uncommonly juniper woodlands. | Moist canyon walls, lower talus slopes, gravelly and sandy soils. |
Elevation | 200–1400 m. (700–4600 ft.) | 1600–2400 m. (5200–7900 ft.) |
Distribution |
CA
|
CO |
Discussion | Mentzelia pectinata occurs in Kern, San Luis Obispo, Santa Barbara, and Tulare counties, around the southern rim of the San Joaquin Valley, extending into the Inner Coast Ranges and the southern foothills of the Sierra Nevada. Petal color varies from orange to yellow, and fully fertile artificial hybrids have been obtained between populations representing the extreme phenotypes (J. E. Zavortink 1966). Phylogenetic studies suggest that M. pectinata and M. congesta have hybridized to form several allopolyploid species (J. M. Brokaw and L. Hufford 2010b) despite their current allopatric distributions. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Mentzelia densa is known only from Chaffee and Fremont counties. It is in the Center for Plant Conservation’s National Collection of Endangered Plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 541. | FNA vol. 12, p. 522. |
Parent taxa | Loasaceae > Mentzelia > sect. Trachyphytum | Loasaceae > Mentzelia > sect. Bartonia |
Sibling taxa | ||
Synonyms | Nuttallia densa | |
Name authority | Kellogg: Proc. Calif. Acad. Sci. 3: 40, fig. 9. (1863) | Greene: Pittonia 3: 99. (1896) |
Web links |