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

Adonis blazingstar, Adonis stickleaf, many flower mentzelia

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

solitary, erect, straight;

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

solitary, erect, straight;

branches distal or along entire stem, distal or proximal longest, antrorse, upcurved; 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 35–112 × 4.3–27.1 mm, widest intersinus distance 2.3–15.3 mm, always on some leaves 4+ mm;

proximal oblanceolate to elliptic, margins dentate to pinnate, teeth or lobes 12–30(–50), perpendicular to leaf axis or antrorse, 1–9 mm;

distal lanceolate, base not clasping, margins serrate to pinnate, teeth or lobes 8–28, perpendicular to slightly antrorse, 0.8–7.5 mm;

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

Bracts

margins pinnate.

margins entire or toothed to pinnate.

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, 11.3–20.4 × 2.9–7.2[–8.9] mm, apex acute to rounded, glabrous abaxially;

stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 10.4–17.8 × 1.9–5.2[–5.6] mm, with or without anthers, second whorl with anthers;

anthers straight after dehiscence, epidermis smooth;

styles (5.4–)8.5–10.9(–13) mm.

Capsules

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

cup-shaped to cylindric, [7.6–]9.1–16.4 × 5.7–9.2 mm, length usually to 2 times diam., sometimes a few more, 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 or sinuous, papillae 4–106 per cell.

2n

= 22.

Mentzelia decapetala

Mentzelia longiloba

Phenology Flowering Jun–Aug(–Oct).
Habitat Rock outcrops, slopes, dry short-grass prairies, riverbanks, roadsides, loam, limestone, sandy, silty, clayey, and gravelly soils.
Elevation 300–2400 m. (1000–7900 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
AZ; CA; CO; NM; TX; UT; n Mexico
[WildflowerSearch map]
[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.)

Varieties 4 (3 in the flora).

Variety pinacatensis J. J. Schenk & L. Hufford is known from the Mexican state of Sonora.

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

Key
1. Seed coat anticlinal cell walls straight, papillae 4–6 per cell; margins of proximal leaf blades dentate.
var. chihuahuaensis
1. Seed coat anticlinal cell walls sinuous, papillae 10–106 per cell; margins of proximal leaf blades pinnate.
→ 2
2. 5 outermost stamens without anthers; leaf blade margin teeth or lobes perpendicular to leaf axis; seed coat cell papillae 67–106 per cell.
var. longiloba
2. 5 outermost stamens with anthers; leaf blade margin teeth or lobes slightly antrorse; seed coat cell papillae 10–21 per cell.
var. yavapaiensis
Source FNA vol. 12, p. 504. FNA vol. 12, p. 520.
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. 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. 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
Subordinate taxa
M. longiloba var. chihuahuaensis, M. longiloba var. longiloba, M. longiloba var. yavapaiensis
Synonyms Bartonia decapetala M. multiflora subsp. longiloba
Name authority (Pursh) Urban: Ber. Deutsch. Bot. Ges. 10: 263. (1892) J. Darlington: Ann. Missouri Bot. Gard. 21: 176. (1934)
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