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Pacific blazing star

cluster blazing star, congested blazingstar, flower baskets, united blazingstar

Habit Plants candelabra-form, 8–45 cm. Plants wandlike or candelabra-form, 7–40(–50) cm.
Basal leaves

persisting;

petiole present or absent;

blade linear-lanceolate to linear, margins usually irregularly deeply lobed, lobes pointed.

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(–22) cm, margins few-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 ovate-lanceolate, 2.9–8.2 × 1.1–1.9 mm, width 1/8–1/2 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 2–6 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.

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, 11–31 × 1.5–3 mm, axillary curved to 250° 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

15–50, 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.

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.

= 18.

Mentzelia obscura

Mentzelia congesta

Phenology Flowering Feb–May. Flowering May–Jul.
Habitat Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. Disturbed slopes, sagebrush scrub, pinyon/juniper woodlands, pine forests.
Elevation 200–1700 m. (700–5600 ft.) 1200–2700 m. (3900–8900 ft.)
Distribution
from FNA
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
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[BONAP county map]
from FNA
CA; ID; NV; OR
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[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 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. 540. FNA vol. 12, p. 535.
Parent taxa Loasaceae > Mentzelia > sect. Trachyphytum Loasaceae > Mentzelia > sect. Trachyphytum
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. 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. tiehmii, M. todiltoensis, M. torreyi, M. tricuspis, M. tridentata, M. uintahensis, M. veatchiana
Synonyms Acrolasia davidsoniana, M. congesta var. davidsoniana
Name authority H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) Torrey & A. Gray: Fl. N. Amer. 1: 534. (1840)
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