Mentzelia obscura |
Mentzelia filifolia |
|
---|---|---|
Pacific blazing star |
narrow-leaf blazingstar |
|
Habit | Plants candelabra-form, 8–45 cm. | Plants biennial, candelabra-form. |
Stems | solitary, erect, straight; branches distal, distal longest, antrorse, straight; hairy. |
|
Leaves | blade 43–94(–115) × (4.3–)7.5–36 mm, widest intersinus distance 1–2.4 mm; proximal oblanceolate to elliptic, margins pinnatisect, lobes 8–20, perpendicular to leaf axis, 3.2–12(–15.7) mm; distal oblanceolate to elliptic, base not clasping, margins pinnatisect, lobes 8–20, perpendicular to leaf axis, 5.6–17.1 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and occasionally needlelike trichomes, adaxial surface with 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 or pinnate. |
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, 13–18.5 × 3.7–6.1 mm, apex acute, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 10.2–14.7(–18) × (1.3–)2.5–4.4 mm, without anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles 10–12.5(–14) mm. |
Capsules | clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
cylindric, 11–19 × 5–7.5 mm, base tapering, not or diminutively 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 sinuous, papillae 42–48 per cell. |
2n | = 36. |
= 20. |
Mentzelia obscura |
Mentzelia filifolia |
|
Phenology | Flowering Feb–May. | Flowering Jul–Aug. |
Habitat | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. | Roadcuts, slopes, dark loam, rocky soils. |
Elevation | 200–1700 m. (700–5600 ft.) | 2100–2200 m. (6900–7200 ft.) |
Distribution |
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
|
AZ; NM |
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 filifolia is known from the Chuska Mountains of Apache County, Arizona, and McKinley and San Juan counties, New Mexico. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 540. | FNA vol. 12, p. 517. |
Parent taxa | Loasaceae > Mentzelia > sect. Trachyphytum | Loasaceae > Mentzelia > sect. Bartonia |
Sibling taxa | ||
Name authority | H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) | J. J. Schenk & L. Hufford: Madroño 57: 251, figs. 1D, 2B. (2010) |
Web links |