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10-petal western star, evening starflower, gumbo-lily, tenpetal blazingstar

Arapien blazingstar

Habit Plants biennial or perennial, bushlike, perennials with ground-level caudices. Plants perennial, bushlike, with subterranean caudices.
Stems

solitary, erect, straight;

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

multiple, erect, zigzag or straight;

branches distal or along entire stem, distal longest or all ± equal, antrorse, straight; hairy.

Leaves

blade 72–295 × 14–45 mm, widest intersinus distance 10.1–23.3 mm;

proximal oblanceolate or elliptic, margins serrate to pinnate, teeth or lobes 16–26, slightly antrorse, 1–16.5 mm;

distal elliptic to lanceolate, base clasping or not, margins serrate to pinnate, teeth or lobes 9–20, slightly antrorse, 5.3–13.7 mm;

surfaces with needlelike trichomes.

blade 15.4–40(–86) × 4–12.2 mm, always some more than 10 mm wide, widest intersinus distance 4–12.2 mm;

proximal oblanceolate to spatulate, margins usually entire, rarely dentate, teeth 0(–4), perpendicular to leaf axis, 0.1–1 mm;

distal oblanceolate, spatulate, or elliptic, base not clasping, margins usually entire, rarely dentate, teeth 0(–4), perpendicular to leaf axis, 0.3–1.4 mm;

abaxial surface with simple grappling-hook, complex grappling-hook, and needlelike trichomes, adaxial surface with simple grappling-hook and needlelike trichomes.

Bracts

margins pinnate.

margins entire.

Flowers

petals white, 47–75 × 13–22.7 mm, apex acute to attenuate, glabrous abaxially;

stamens white to yellow, 5 outermost petaloid, filaments spatulate, strongly clawed, 48–75 × 12–23 mm, without anthers, second whorl with anthers;

anthers straight after dehiscence, epidermis smooth;

styles 36–53 mm.

petals golden yellow, 8.2–12.2(–15.2) × 2.4–5 mm, apex acute, glabrous abaxially;

stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 5.6–11(–13.5) × 1.4–3 mm, with anthers, second whorl with anthers;

anthers usually twisted after dehiscence, epidermis papillate;

styles 5.5–9.4 mm.

Capsules

cylindric, 30–43 × 12–17 mm, base tapering, not longitudinally ridged.

cup-shaped, 5–8.4 × 3.1–6 mm, base tapering to rounded, not longitudinally ridged.

Seeds

2.3–4 mm;

coat anticlinal cell walls straight, papillae 4–10 per cell.

coat anticlinal cell walls straight, papillae 3–5 per cell.

2n

= 22.

= 22.

Mentzelia decapetala

Mentzelia argillosa

Phenology Flowering Jun–Aug(–Oct). Flowering Jun–Aug.
Habitat Rock outcrops, slopes, dry short-grass prairies, riverbanks, roadsides, loam, limestone, sandy, silty, clayey, and gravelly soils. Sparsely vegetated steep cliffs or slopes composed of gypsum-rich clayey and gravelly soils.
Elevation 300–2400 m. (1000–7900 ft.) 1600–1900 m. (5200–6200 ft.)
Distribution
from FNA
CO; IA; IL; KS; MN; MT; NE; NM; OK; SD; TX; UT; WY; AB; MB; SK
[WildflowerSearch map]
[BONAP county map]
from FNA
UT
[BONAP county map]
Discussion

Mentzelia decapetala is introduced in Grundy County, Illinois. It appears to be native throughout the rest of its distribution.

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

Mentzelia argillosa is endemic to the Arapien Shale formation in Sevier and Sanpete counties.

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

Source FNA vol. 12, p. 504. FNA vol. 12, p. 507.
Parent taxa Loasaceae > Mentzelia > sect. Bartonia 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. 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
M. affinis, M. albescens, M. albicaulis, M. argillicola, 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. tiehmii, M. todiltoensis, M. torreyi, M. tricuspis, M. tridentata, M. uintahensis, M. veatchiana
Synonyms Bartonia decapetala Nuttallia argillosa
Name authority (Pursh) Urban: Ber. Deutsch. Bot. Ges. 10: 263. (1892) J. Darlington: Ann. Missouri Bot. Gard. 21: 153. (1934)
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