Mentzelia jonesii |
Mentzelia congesta |
|
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Jones stickleaf, Jones' blazing star |
cluster blazing star, congested blazingstar, flower baskets, united blazingstar |
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Habit | Plants candelabra-form, 20–40(–50) cm. | Plants wandlike or candelabra-form, 7–40(–50) cm. |
Basal leaves | persisting; petiole present or absent; blade linear-lanceolate to linear, margins deeply lobed to dentate. |
persisting; petiole present or absent; blade linear-lanceolate to linear, margins usually deeply to shallowly lobed, rarely entire. |
Cauline leaves | petiole absent; blade ovate-lanceolate to linear, to 15 cm, margins deeply to shallowly lobed or entire. |
petiole present or absent (proximal leaves), absent (distal leaves); blade linear-lanceolate to linear (proximal leaves), ovate-lanceolate (distal leaves), to 9 cm, margins deeply to shallowly lobed or entire. |
Bracts | green, ovate to lanceolate, 3.7–5.9 × 0.8–3.9 mm, width 1/8–2/3 length, not concealing capsule, margins entire. |
mostly white with green margins, conspicuous and showy, outer broadly ovate, inner obovate, outer 7–14.7 × 4.2–10.4 mm, inner 4.1–5.8 × 2.7–3.5 mm, width 1/2–7/8 length, concealing capsule, margins usually deeply 3–9-lobed to toothed, rarely entire. |
Flowers | sepals (2–)4–8(–10) mm; petals yellow to orange proximally, yellow distally, (6–)8–22 mm, apex acute to rounded; stamens 20+, 3–10 mm, filaments monomorphic, filiform, unlobed; styles 4–10 mm. |
sepals 1–4 mm; petals orange proximally, pale yellow to yellow distally, 2–8(–10) mm, apex retuse; stamens 20–40, 1.5–5 mm, filaments monomorphic, filiform, unlobed; styles 1.5–5 mm. |
Capsules | clavate, 15–38 × 2–4 mm, axillary curved to 180° or S-shaped at maturity, usually inconspicuously longitudinally ribbed. |
cylindric or clavate, 5–12 × 2–3 mm, axillary curved to 10° at maturity, usually inconspicuously longitudinally ribbed. |
Seeds | 15–30, in 2+ rows distal to mid fruit, tan, dark-mottled, 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. |
10–25, in 2+ rows distal to mid fruit, tan, dark-mottled or not, irregularly polygonal, surface tessellate 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 | = 36, 54. |
= 18. |
Mentzelia jonesii |
Mentzelia congesta |
|
Phenology | Flowering Mar–May. | Flowering May–Jul. |
Habitat | Sandy to rocky washes, fans, or flats, creosote-bush scrub, Joshua-tree or saguaro woodlands. | Disturbed slopes, sagebrush scrub, pinyon/juniper woodlands, pine forests. |
Elevation | 200–1500 m. (700–4900 ft.) | 1200–2700 m. (3900–8900 ft.) |
Distribution |
AZ; CA; NV; UT
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CA; ID; NV; OR
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Discussion | Mentzelia jonesii is widespread throughout southeastern California and western and southern Arizona. However, tetraploid populations have been found only in California and far northwestern Arizona. Hexaploids in California have previously been called M. californica. The ranges of M. jonesii and the diploid, M. nitens, overlap in southern Inyo County, California, and these species are difficult to distinguish morphologically without mature seeds; sepal and petal lengths, which have sometimes been used to distinguish them, overlap completely. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Mentzelia congesta is easily distinguished from other species in sect. Trachyphytum by its large, mostly white bracts. However, the bracts of M. congesta are strikingly similar to those of M. involucrata in sect. Bicuspidaria (see discussion under 53. M. involucrata). Phylogenetic studies suggest that the genome of M. congesta is present in more than half of the polyploid taxa in sect. Trachyphytum, including all species that exhibit bracts with partially white bases (J. M. Brokaw and L. Hufford 2010b). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 537. | FNA vol. 12, p. 535. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | M. albicaulis var. jonesii, M. californica, M. nitens var. jonesii | Acrolasia davidsoniana, M. congesta var. davidsoniana |
Name authority | (Urban & Gilg) H. J. Thompson & J. E. Roberts: Phytologia 21: 282. (1971) | Torrey & A. Gray: Fl. N. Amer. 1: 534. (1840) |
Web links |