Mentzelia veatchiana |
Mentzelia pachyrhiza |
|
---|---|---|
Veatch's blazing star, white-stem blazingstar, white-stem stick-leaf |
big-root stickleaf, Coahuila blazingstar |
|
Habit | Plants candelabra-form, (5–)20–50 cm. | Plants perennial, with tubers. |
Stems | erect, to 50 cm. |
|
Leaves | petiole mostly 3–20 mm, less than 3 mm only on smallest, distalmost leaves; blade ovate to hastate, basally lobed or unlobed, to 4 × 3 cm, base usually acute to obtuse, sometimes attenuate or hastate, margins usually serrate, sometimes crenate, apex acute. |
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Basal leaves | persisting; petiole present or absent; blade linear-lanceolate, margins deeply to shallowly lobed. |
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Cauline leaves | petiole absent; blade ovate-lanceolate to lanceolate, to 17 cm, margins usually deeply lobed to dentate, rarely entire. |
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Bracts | usually green with prominent white base usually conspicuously extending outwards from midvein, rarely green, usually ovate, rarely lanceolate, 3.3–6.2 × 1.5–3.2 mm, width 1/4–7/8 length, not concealing capsule, margins usually 3–7-lobed, rarely entire. |
|
Pedicels | (fruiting) (0–)2 × 2 mm. |
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Flowers | sepals 2–5 mm; petals red to orange proximally, orange to yellow distally, 4–7(–10) mm, apex retuse; stamens 20+, 3–7 mm, filaments monomorphic, filiform, unlobed; styles (3–)3.5–6 mm. |
petals orange, 5–11.5 × 3–5 mm, apex acute to rounded, hairy abaxially on distal 1/2; stamens 15–45, 4–8 mm, filaments usually monomorphic, filiform, rarely heteromorphic, outermost slightly spatulate, inner filiform; style 3–7.5 mm. |
Capsules | clavate, 8–28 × 2–4 mm, axillary curved to 70° at maturity, usually inconspicuously longitudinally ribbed. |
subcylindric to clavate, 6–10 × 1.5–2.3 mm, base tapering gradually, capsule and pedicel not well-differentiated, walls thin, brittle. |
Seeds | 15–35, 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 or equal to 1/2 as tall as wide at maturity. |
2–3 per capsule, oblong, with transverse folds. |
2n | = 54. |
= 22. |
Mentzelia veatchiana |
Mentzelia pachyrhiza |
|
Phenology | Flowering Mar–Jun. | Flowering May–Nov. |
Habitat | Loamy to sandy soils, grasslands, desert scrub, oak-pine woodlands. | Steep limestone cliffs, gravelly slopes of gypseous clayey soils, desert scrub and Larrea communities. |
Elevation | 200–2500 m. [700–8200 ft.] | 900–2000 m. [3000–6600 ft.] |
Distribution |
AZ; CA; NV; OR
|
TX; Mexico (Chihuahua, Coahuila, Durango, Nuevo León) |
Discussion | Mentzelia veatchiana is the most common and widely distributed hexaploid species in sect. Trachyphytum. It exhibits considerable morphological variation and can be difficult to distinguish from M. montana in northern California. Like the larger-flowered M. pectinata, M. veatchiana has interfertile populations with petal colors ranging from orange to yellow (J. E. Zavortink 1966). When bearing orange petals, M. veatchiana is easily distinguished from other species. Reports of M. veatchiana from Utah are based on specimens treated here as M. montana. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Mentzelia pachyrhiza, native to the Chihuahuan Desert, reaches the flora area only in southern Brewster and Presidio counties. In southwestern Texas and northeastern Chihuahua, where M. pachyrhiza and M. oligosperma have overlapping ranges, H. J. Thompson and A. M. Powell (1981) reported that the former was found at elevations usually below 1100 meters in the Larrea zone, below the elevation of junipers and M. oligosperma. Thompson and Powell allied M. pachyrhiza with M. oligosperma and the South American M. grisebachii Urban & Gilg, now treated as a synonym of M. parvifolia Urban & Gilg ex Kurtz (M. Weigend 2007b). This placement is consistent with phylogenetic studies (J. Grissom and L. Hufford, unpubl.), which show that M. pachyrhiza is the sister species of M. parvifolia; they together are the sister of M. oligosperma and the Mexican M. pattersonii B. L. Turner. I. M. Johnston’s (1940) assertion that the large tuber of M. pachyrhiza is unique in sect. Mentzelia is incorrect. Tubers, often carrot-shaped, are common among the perennial species of the section. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 543. | FNA vol. 12, p. 529. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | M. albicaulis var. veatchiana | |
Name authority | Kellogg: Proc. Calif. Acad. Sci. 2: 99, fig. 28. (1863) | I. M. Johnston: J. Arnold Arbor. 21: 71. (1940) |
Web links |