Flora of North America species comparison

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Mentzelia decapetala

Mentzelia sect. Bartonia

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

western star
Habit Plants biennial or perennial, bushlike, perennials with ground-level caudices. Herbs, winter annual, biennial, or short-lived perennial.
Stems

solitary, erect, straight;

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

basal rosette present, not persistent, proximalmost internodes to 10+ mm;

blade without broad basal lobes, margins entire, toothed, pinnate, or pinnatisect, flat.
Bracts

margins 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.

stamens all fertile or 5+ outer sterile;

filaments heteromorphic, outer dorsiventrally flattened, linear, elliptic, spatulate, or oblanceolate, usually petaloid, sometimes not, inner filiform, unlobed;

ovules (and seeds) oriented perpendicular to long axis of ovary.
Capsules

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

cup-shaped to lingulate or cylindric, straight.
Seeds

2.3–4 mm;

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

ovoid, flattened dorsiventrally, winged;

seed coat cells polygonal, ± isodiametric, anticlinal walls straight, wavy, or sinuous.
2n

= 22.

Mentzelia decapetala

Mentzelia sect. Bartonia
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]
w North America; n Mexico; c North America; s South America; arid to mesic regions
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.)

Species 51 (51 in the flora).

In the following keys and descriptions, three trichome types are defined as follows. Simple grappling-hook trichomes have a cylindric stalk that is unbarbed except at the apex, which terminates with four (or sometimes fewer) retrorse barbs. Complex grappling-hook trichomes have a tapered stalk that is retrorsely barbed along its length and capped usually by four retrorse barbs. Needlelike trichomes have swollen bases resting on a pedestal formed by a ring of epidermal cells, are relatively long and pointed, and bear antrorse barbs or knobs along their length.

Leaf blade intersinus distance is measured across the leaf blade between opposite sinuses; for leaves with entire margins, it is the width of the leaf blade. Anther papillae and seed coat anticlinal wall shape can be observed at 10/x magnification; greater magnification (30–40/x) is needed to see seed coat cell papillae in species with numerous small papillae.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Petals white.
→ 2
2. Anther epidermis papillate.
→ 3
3. Leaf blade widest intersinus distances 9.5–29 mm.
M. hualapaiensis
3. Leaf blade widest intersinus distances 0.8–9.1 mm.
→ 4
4. 5 outermost stamens without anthers; New Mexico, Texas.
M. humilis
4. 5 outermost stamens with anthers; Arizona.
M. canyonensis
2. Anther epidermis smooth.
→ 5
5. Petals 13–22.7 mm wide; stamens white to yellow.
M. decapetala
5. Petals 1.9–10.3 mm wide; stamens white.
→ 6
6. Petals 22.6–49 × 3.6–10.3 mm; bracts pinnate.
M. nuda
6. Petals 14.7–22(–24.4) × 1.9–4.4 mm; bracts entire or dentate.
M. strictissima
1. Petals light to golden yellow.
→ 7
7. Petals hairy abaxially.
→ 8
8. Branches perpendicular to stem, especially proximal and mid-stem, or slightly antrorse, especially distal, ± equal; Montrose County, Colorado.
M. paradoxensis
8. Branches antrorse, proximal longer than distal, all usually extending to near the distal end of plant; Arizona, Colorado (including Montrose County), New Mexico, Utah.
→ 9
9. 5 outermost stamens with anthers; margins of proximal leaf blades with teeth 0.5–4 mm; Colorado.
M. marginata
9. 5 outermost stamens usually without anthers; margins of proximal leaf blades with teeth or lobes 1.2–6(–9) mm, always some more than 4 mm; Arizona, Colorado, New Mexico, Utah.
M. cronquistii
7. Petals glabrous abaxially.
→ 10
10. Anther epidermis papillate.
→ 11
11. 5 outermost stamens with anthers.
→ 12
12. Leaf blades 4–12.2 mm wide, always some more than 10 mm wide, margins usually entire, rarely dentate, teeth 0(–4), 0.1–1.4 mm; seed coat cell papillae 3–5 per cell; Utah.
M. argillosa
12. Leaf blades 1.5–8.8 mm wide, margins entire, dentate, or pinnate, teeth or lobes 0–8 (always some leaves with 5+ teeth or lobes), 0.1–2 mm (always some more than 1.4 mm); seed coat cell papillae 5–8 per cell; Nevada.
M. argillicola
11. 5 outermost stamens without anthers.
→ 13
13. Leaf blade widest intersinus distances 9.5–29 mm.
M. hualapaiensis
13. Leaf blade widest intersinus distances 1–4.2 mm.
→ 14
14. Second whorl of stamens without anthers.
M. perennis
14. Second whorl of stamens with anthers.
→ 15
15. Seed coat anticlinal cell walls straight, papillae 38–45 per cell; Texas.
M. saxicola
15. Seed coat anticlinal cell walls sinuous, papillae 6–12 per cell; New Mexico.
M. todiltoensis
10. Anther epidermis smooth.
→ 16
16. Capsules longitudinally ridged.
M. rusbyi
16. Capsules not longitudinally ridged.
→ 17
17. Stems multiple, from subterranean branching caudices.
→ 18
18. 5 outermost stamens without anthers.
M. springeri
18. 5 outermost stamens with anthers.
→ 19
19. Bases of distal leaf blades clasping.
→ 20
20. Leaf blade surfaces densely hairy, whitish, abaxial surfaces with complex grappling-hook and needlelike trichomes; Ash Meadows, Nye County, Nevada.
M. leucophylla
20. Leaf blade surfaces moderately hairy, green, abaxial surfaces with complex grappling-hook trichomes only; se California and s Nevada (including Nye County).
→ 21
21. Leaf blades 5.8–9.1 mm wide, widest intersinus distances 4.6–7.1 mm; margins of distal leaf blades with 0–6 teeth; seed coat cell papillae 15–46 per cell.
M. tiehmii
21. Leaf blades 7.6–41.2 mm wide, widest intersinus distances 5.1–35.3 mm; margins of distal leaves with 6–16 teeth; seed coat cell papillae 6–17 per cell.
M. oreophila
19. Bases of distal leaf blades not clasping.
→ 22
22. Margins of proximal leaf blades 3-fid or pinnate to pinnatisect (rarely entire in M. librina).
→ 23
23. Filaments of 5 outermost stamens broadly spatulate, strongly clawed.
→ 24
24. Margins of proximal leaf blades pinnate to pinnatisect, lobes 4–12.
M. uintahensis
24. Margins of proximal leaf blades usually 3-fid, rarely entire or pinnate, teeth or lobes usually 2, rarely 0 or 4.
M. librina
23. Filaments of 5 outermost stamens narrowly spatulate or oblanceolate, slightly clawed.
→ 25
25. Petals 2.9–3.8 mm wide; filaments of 5 outermost stamens less than 1.3–1.9 mm wide; Utah.
M. flumensevera
25. Petals 5.1–9 mm wide; filaments of 5 outermost stamens 2–4.5 mm wide; Colorado.
M. multicaulis
22. Margins of proximal leaf blades entire or dentate to serrate.
→ 26
26. Stems glabrescent, smooth to the touch.
M. polita
26. Stems hairy.
→ 27
27. Margins of proximal leaves entire.
→ 28
28. Petals 7.4–11 × 2.6–3.4 mm; margins of distal leaf blades entire; filaments of 5 outermost stamens slightly clawed; Arizona.
M. memorabilis
28. Petals 12.5–17.2 × 6.1–11.2 mm; margins of distal leaf blades entire or dentate; filaments of 5 outermost stamens strongly clawed; Colorado.
M. rhizomata
27. Margins of proximal leaf blades dentate or serrate, with 4–12 teeth.
→ 29
29. Petals 6.7–9.2 mm wide; seed coat cell papillae 11–15 per cell.
M. goodrichii
29. Petals 2.3–5.9 mm wide; seed coat cell papillae 3–6 per cell.
→ 30
30. Stems zigzag; margins of proximal leaf blades with 4–6 teeth, each 0.5–0.6 × 1.2–1.5 mm.
M. shultziorum
30. Stems straight; margins of proximal leaf blades with 8–12 teeth, each 1–4 × 1.7–6 mm.
M. puberula
17. Stems solitary or, if multiple, from ground-level caudices.
→ 31
31. 5 outermost stamens not petaloid, with anthers, filaments linear to narrowly elliptic or narrowly spatulate, 0.5–2(–2.5) mm wide, if narrowly spatulate, to 1.5 mm wide.
→ 32
32. Petals 23.5–70 mm; styles 20.4–57 mm; 5 outermost stamens 17.7–55 mm.
M. laevicaulis
32. Petals (6.1–)7.3–15.8(–18) mm; styles 3.7–13 mm; 5 outermost stamens 4–13.2 mm.
→ 33
33. Petals 11.7–15.8(–18) mm; 5 outermost stamens 10.2–13.2 mm.
M. inyoensis
33. Petals (6.1–)7.3–10 mm; 5 outermost stamens 4–8 mm.
M. candelariae
31. 5 outermost stamens petaloid, with or without anthers, filaments narrowly spatulate to elliptic or oblanceolate, 1–9.7 mm wide, if narrowly spatulate and less than 1.5 mm wide, then without anthers.
→ 34
34. Margins of distal leaf blades pinnatisect (sometimes pinnate in M. laciniata).
→ 35
35. Petals 30–42.2 mm; 5 outermost stamens 27–37.4 mm; styles 24–32.4 mm.
M. conspicua
35. Petals 8.3–23.8(–26) mm; 5 outermost stamens 6.5–20.4 mm; styles 6.1–12.5(–14) mm.
→ 36
36. Petals 8.3–13 mm; 5 outermost stamens 6.5–10.7 mm; Colorado, Nevada, Utah.
M. lagarosa
36. Petals 13–23.8(–26) mm; 5 outermost stamens 10.2–20.4 mm; Arizona, Colorado, New Mexico.
→ 37
37. Lobes of distal leaf blades strongly antrorse; branches upcurved; Arizona, New Mexico.
M. holmgreniorum
37. Lobes of distal leaf blades slightly antrorse or perpendicular to leaf axis; branches straight; Arizona, Colorado, New Mexico.
→ 38
38. Seed coat cell papillae 42–48 per cell; Chuska Mountains of Arizona and New Mexico.
M. filifolia
38. Seed coat cell papillae 5–14 per cell; Colorado, New Mexico (not Chuska Mountains).
M. laciniata
34. Margins of distal leaf blades entire, dentate, serrate, or pinnate.
→ 39
39. Bases of distal leaf blades clasping (rarely a few not clasping in M. pterosperma).
→ 40
40. Capsules cup-shaped; Arizona, California, Colorado, Nevada, Utah.
M. pterosperma
40. Capsules cylindric; Kansas, Missouri, Oklahoma, Texas.
M. albescens
39. Bases of distal leaf blades not clasping (sometimes a few clasping in M. mexicana).
→ 41
41. Filaments of 5 outermost stamens strongly clawed; on black (to sometimes reddish) volcanic cinder cone soils in San Francisco Volcanic Field, Coconino County, Arizona.
M. collomiae
41. Filaments of 5 outermost stamens slightly clawed; not on black (to sometimes reddish) volcanic cinder cone soils in San Francisco Volcanic Field, Coconino County, Arizona.
→ 42
42. Seed coat cell anticlinal walls straight.
→ 43
43. Capsule length more than 2 times diam. (occasionally a few slightly less in M. reverchonii).
→ 44
44. Styles 8.7–11.4(–13) mm; Colorado, New Mexico, Oklahoma, Texas.
M. reverchonii
44. Styles 5.6–7.8 mm; Montana, Utah, Wyoming.
M. pumila
43. Capsule length to 2 times diam. (sometimes a few more in M. longiloba).
→ 45
45. Capsule bases tapering; seed coat cell papillae 4–6 per cell.
M. longiloba
45. Capsule bases rounded; seed coat cell papillae 8–45 per cell.
→ 46
46. Seed coat cell papillae 8–12 per cell; leaf blade widest intersinus distances 3.4–19 mm.
M. mexicana
46. Seed coat cell papillae 38–45 per cell; leaf blade widest intersinus distances 1.6–3.4 mm.
M. saxicola
42. Seed coat cell anticlinal walls wavy to sinuous.
→ 47
47. Margins of proximal leaves with 4–12 teeth or lobes.
→ 48
48. Plants candelabra-form; proximal branches not decumbent; largest leaf trichomes with pearly white bases; leaf blade margin teeth with proximal side antrorse, distal side perpendicular to leaf axis; Arizona, Nevada, Utah.
M. integra
48. Plants bushlike; proximal branches decumbent; largest leaf trichomes without pearly white bases; leaf blade margin teeth or lobes perpendicular to leaf axis; c Colorado.
M. densa
47. Margins of proximal leaves with 14–38 teeth or lobes (occasionally 10–38 in M. speciosa).
→ 49
49. Seed coat cell anticlinal walls wavy; petals golden yellow; leaf blades 43.6–233 mm, always some 146+ mm.
M. speciosa
49. Seed coat cell anticlinal walls sinuous; petals light to golden yellow; leaf blades 32.8–125(–146) mm.
→ 50
50. 5 outermost stamens with anthers.
→ 51
51. Leaf blade widest intersinus distances 2.3–7.1 mm, always some leaves 4+ mm; branches upcurved.
M. longiloba
51. Leaf blade widest intersinus distances 1–2.9 mm; branches straight.
M. sivinskii
50. 5 outermost stamens without anthers.
→ 52
52. Leaf blade widest intersinus distances 1–3.9 mm; petals light yellow.
M. procera
52. Leaf blade widest intersinus distances 2.1–13.7(–14) mm, always some leaves 4+ mm; petals light to golden yellow.
→ 53
53. Seed coat cell papillae 10–21 or 67–106 per cell; Arizona, California, Colorado, New Mexico, Utah.
M. longiloba
53. Seed coat cell papillae 29–48 per cell; Colorado, Nebraska, New Mexico, Wyoming.
→ 54
54. Branches distal or along entire stem, straight.
M. chrysantha
54. Branches distal, upcurved.
M. multiflora
Source FNA vol. 12, p. 504. FNA vol. 12, p. 498. Authors: John J. Schenk, Larry Hufford.
Parent taxa Loasaceae > Mentzelia > sect. Bartonia Loasaceae > Mentzelia
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
Subordinate taxa
M. albescens, M. argillicola, M. argillosa, M. candelariae, M. canyonensis, M. chrysantha, M. collomiae, M. conspicua, M. cronquistii, M. decapetala, M. densa, M. filifolia, M. flumensevera, M. goodrichii, M. holmgreniorum, M. hualapaiensis, M. humilis, M. integra, M. inyoensis, M. laciniata, M. laevicaulis, M. lagarosa, M. leucophylla, M. librina, M. longiloba, M. marginata, M. memorabilis, M. mexicana, M. multicaulis, M. multiflora, M. nuda, M. oreophila, M. paradoxensis, M. perennis, M. polita, M. procera, M. pterosperma, M. puberula, M. pumila, M. reverchonii, M. rhizomata, M. rusbyi, M. saxicola, M. shultziorum, M. sivinskii, M. speciosa, M. springeri, M. strictissima, M. tiehmii, M. todiltoensis, M. uintahensis
Synonyms Bartonia decapetala M.
Name authority (Pursh) Urban: Ber. Deutsch. Bot. Ges. 10: 263. (1892) (Torrey & A. Gray) Bentham & Hooker f.: Gen. Pl. 1 : 804. (1867)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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