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Pacific blazing star

Jerry's blazingstar, Tiehm's blazing star

Habit Plants candelabra-form, 8–45 cm. Plants perennial, bushlike, with subterranean caudices.
Stems

multiple, erect, straight;

branches along entire stem, all ± equal, antrorse, upcurved; hairy.

Leaves

blade 19–47.5 × 5.8–9.1 mm, widest intersinus distance 4.6–7.1 mm;

proximal oblanceolate to elliptic, margins dentate, teeth 6–20, perpendicular to leaf axis, 0.5–1.9 mm;

distal lanceolate, deltate, or cordate, base clasping, margins entire or dentate, teeth 0–6, perpendicular to leaf axis, 0.4–1.4 mm;

abaxial surface with complex grappling-hook trichomes, adaxial surface with complex grappling-hook and needlelike trichomes, both surfaces green, moderately hairy.

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.

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, 7.7–10.8 × 1.8–4.8 mm, apex rounded, glabrous abaxially;

stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 7–7.3 × 1.2–2 mm, with anthers, second whorl with anthers;

anthers twisted after dehiscence, epidermis smooth;

styles 5.8–8 mm.

Capsules

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

cup-shaped, 4–6.6 × 4–7.4 mm, base rounded, 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 straight, papillae 15–46 per cell.

2n

= 36.

Mentzelia obscura

Mentzelia tiehmii

Phenology Flowering Feb–May. Flowering Jun–Aug.
Habitat Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. White, sparsely vegetated clay knolls rich in gypsum.
Elevation 200–1700 m. (700–5600 ft.) 1500–1600 m. (4900–5200 ft.)
Distribution
from FNA
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
NV
[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.)

Mentzelia tiehmii occurs in Lincoln and Nye counties.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 12, p. 540. FNA vol. 12, p. 510.
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. 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. todiltoensis, M. torreyi, M. tricuspis, M. tridentata, M. uintahensis, M. veatchiana
Name authority H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) N. H. Holmgren & P. K. Holmgren: Syst. Bot. 27: 748, fig. 1. (2002)
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