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Pacific blazing star

upright blazingstar

Habit Plants candelabra-form, 8–45 cm. Plants biennial, usually candelabra-form, rarely bushlike.
Stems

solitary, erect, straight;

branches distal or occasionally along entire stem, distal or proximal longest, antrorse, straight or upcurved; hairy.

Leaves

blade 38.3–108 × 5.3–14.9 mm, widest intersinus distance 1.7–3.9 mm;

proximal oblanceolate to elliptic, margins pinnate, lobes 14–22(–26), perpendicular to leaf axis, 1.8–4.5 mm;

distal elliptic to lanceolate, base not clasping, margins pinnate, lobes 6–18, perpendicular to leaf axis, 1.3–4.5 mm;

abaxial surface with simple grappling-hook, complex grappling-hook, and occasionally needlelike trichomes, adaxial surface with simple grappling-hook and 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 toothed to 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 light yellow, 9.5–16.8 × 3.4–5.6 mm, apex usually rounded, rarely acute, glabrous abaxially;

stamens light yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 8.2–14.6 × 2.3–3.4 mm, without anthers, second whorl with anthers;

anthers straight after dehiscence, epidermis smooth;

styles 7.1–12.6 mm.

Capsules

clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed.

cup-shaped to cylindric, 9.8–18.8 × 5.2–7.3 mm, base tapering, not 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 28–68 per cell.

2n

= 36.

Mentzelia obscura

Mentzelia procera

Phenology Flowering Feb–May. Flowering Jul–Aug.
Habitat Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. Dry hillsides, roadcuts, roadsides, sandy, clayey, or silty soils.
Elevation 200–1700 m. (700–5600 ft.) 1400–2500 m. (4600–8200 ft.)
Distribution
from FNA
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; NM; n Mexico
[BONAP county map]
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.)

Source FNA vol. 12, p. 540. FNA vol. 12, p. 523.
Parent taxa Loasaceae > Mentzelia > sect. Trachyphytum Loasaceae > Mentzelia > sect. Bartonia
Sibling taxa
M. affinis, M. albescens, M. albicaulis, M. argillicola, M. argillosa, M. aspera, M. asperula, M. candelariae, M. canyonensis, M. chrysantha, M. collomiae, M. congesta, M. conspicua, M. crocea, M. cronquistii, M. decapetala, M. densa, M. desertorum, M. dispersa, M. eremophila, M. filifolia, M. floridana, M. flumensevera, M. goodrichii, M. gracilenta, M. hirsutissima, M. holmgreniorum, M. hualapaiensis, M. humilis, M. integra, M. involucrata, M. inyoensis, M. isolata, M. jonesii, M. laciniata, M. laevicaulis, M. lagarosa, M. leucophylla, M. librina, M. lindheimeri, M. lindleyi, M. longiloba, M. marginata, M. memorabilis, M. mexicana, M. micrantha, M. mollis, M. monoensis, M. montana, M. multicaulis, M. multiflora, M. nitens, M. nuda, M. oligosperma, M. oreophila, M. pachyrhiza, M. packardiae, M. paradoxensis, M. pectinata, M. perennis, M. polita, M. procera, M. pterosperma, M. puberula, M. pumila, M. ravenii, M. reflexa, M. reverchonii, M. rhizomata, M. rusbyi, M. saxicola, M. shultziorum, M. sivinskii, M. speciosa, M. springeri, M. strictissima, M. thompsonii, M. tiehmii, M. todiltoensis, M. torreyi, M. tricuspis, M. tridentata, M. uintahensis, M. veatchiana
M. affinis, M. albescens, M. albicaulis, M. argillicola, M. argillosa, M. aspera, M. asperula, M. candelariae, M. canyonensis, M. chrysantha, M. collomiae, M. congesta, M. conspicua, M. crocea, M. cronquistii, M. decapetala, M. densa, M. desertorum, M. dispersa, M. eremophila, M. filifolia, M. floridana, M. flumensevera, M. goodrichii, M. gracilenta, M. hirsutissima, M. holmgreniorum, M. hualapaiensis, M. humilis, M. integra, M. involucrata, M. inyoensis, M. isolata, M. jonesii, M. laciniata, M. laevicaulis, M. lagarosa, M. leucophylla, M. librina, M. lindheimeri, M. lindleyi, M. longiloba, M. marginata, M. memorabilis, M. mexicana, M. micrantha, M. mollis, M. monoensis, M. montana, M. multicaulis, M. multiflora, M. nitens, M. nuda, M. obscura, M. oligosperma, M. oreophila, M. pachyrhiza, M. packardiae, M. paradoxensis, M. pectinata, M. perennis, M. polita, M. pterosperma, M. puberula, M. pumila, M. ravenii, M. reflexa, M. reverchonii, M. rhizomata, M. rusbyi, M. saxicola, M. shultziorum, M. sivinskii, M. speciosa, M. springeri, M. strictissima, M. thompsonii, M. tiehmii, M. todiltoensis, M. torreyi, M. tricuspis, M. tridentata, M. uintahensis, M. veatchiana
Synonyms Nuttallia procera, M. pumila var. procera
Name authority H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) (Wooton & Standley) J. J. Schenk & L. Hufford: Madroño 57: 247. (2010)
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