Mentzelia pectinata |
Mentzelia involucrata |
|
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San Joaquin blazing star |
sand blazing star, white-bract blazing star |
|
Habit | Plants candelabra-form, (8–)20–50(–60) cm. | Plants 7–35(–45) cm. |
Basal leaves | persisting; petiole present or absent; blade lanceolate to linear, margins deeply to shallowly lobed. |
petioles present or absent; blade lanceolate, to 10(–16) cm; margins shallowly to deeply lobed, lobes acute. |
Cauline leaves | petiole absent; blade ovate to linear, to 12 cm, margins deeply lobed to dentate. |
petioles absent; blade ovate to lanceolate, to 10(–16) cm, base often cordate-clasping, margins deeply to shallowly lobed, lobes acute. |
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. |
white with green margins, conspicuous, concealing pedicel, ovary, and capsule. |
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 white to pale yellow, usually with orange veins, obovate, 13–65 mm, apex mucronate; stamens 4–26 mm, less than 1/2 petal length, all fertile, none petaloid (flowers appearing to have 5 petals); filaments ± monomorphic, linear, distally 2-lobed, lobes 0.5–2 mm; anther stalk shorter or longer than filament lobes; style 8–30 mm. |
Capsules | clavate, 12–35 × 2–4 mm, axillary curved to 90° at maturity, usually inconspicuously longitudinally ribbed. |
cylindric to cup-shaped, 14–25(–30) × 5–10 mm, erect. |
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. |
usually constricted proximal to middle; seed coat anticlinal cell walls wavy. |
2n | = 18. |
= 18. |
Mentzelia pectinata |
Mentzelia involucrata |
|
Phenology | Flowering Mar–May. | Flowering Jan–May. |
Habitat | Slopes of sandy or gray-white silty soils, grasslands, oak savannas, uncommonly juniper woodlands. | Washes, fans, slopes, desert scrub. |
Elevation | 200–1400 m. (700–4600 ft.) | 50–900 m. (200–3000 ft.) |
Distribution |
CA
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AZ; CA; Mexico (Baja California, Sonora)
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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 involucrata is easily distinguished from other species in sect. Bicuspidaria by its large white bracts, which are strikingly similar to those of M. congesta in sect. Trachyphytum. Phylogenetic studies show that these species are not closely related, suggesting a homoplasious origin of the characteristic (J. M. Brokaw and L. Hufford, 2010). Populations exhibiting petals longer than 3 cm have previously been called var. megalantha. However, a study by G. S. Daniels (1970) suggested that insufficient geographic and morphological discontinuities exist for recognition of varieties. P. A. Munz (1974) mistakenly cited var. megalantha as Mentzelia involucrata subsp. megalantha I. M. Johnston, a name never validly published. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 541. | FNA vol. 12, p. 525. |
Parent taxa | Loasaceae > Mentzelia > sect. Trachyphytum | Loasaceae > Mentzelia > sect. Bicuspidaria |
Sibling taxa | ||
Synonyms | M. involucrata var. megalantha | |
Name authority | Kellogg: Proc. Calif. Acad. Sci. 3: 40, fig. 9. (1863) | S. Watson: Proc. Amer. Acad. Arts 20: 367. (1885) |
Web links |