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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

MENTZELIA BLAZING STAR

Joshua M. Brokaw, John J. Schenk & Barry Prigge


Annual to perennial herb; hairs barbed to needle-like, not stinging; stems pale pink or generally ± white, branched or not. Leaf: linear to ovate, entire to pinnate-lobed; basal in rosettes, generally petioled; cauline generally sessile, ± reduced distally on stem. Inflorescence: generally cyme (or flower 1); bracts green to white, margin green. Flower: sepals lanceolate to deltate, persistent; petals generally 5, free, white to yellow or orange; stamens generally many, ± free, generally unequal, inner filaments generally thread-like; outermost stamens opposite sepal lobes generally modified, ± widened, or petal-like with anther or not; ovary generally cylindric, placentas generally 3, style thread-like, stigma 3-furrowed or -lobed. Fruit: capsule, cup-, barrel-, or urn-shaped to narrowly cylindric, occasionally curved. Seed: generally many, shape variable.
± 100 species: western North America, ± tropical America. [Darlington 1934 Ann Missouri Bot Gard 21:103–226]

Key to Mentzelia

1. Fruit > 4 mm wide, cup-shaped to cylindric or barrel-shaped, or fruit 3–6 mm wide and urn-shaped; seeds transverse-folded or ridged at middle with beak-like end, fusiform and ribbed lengthwise, or lenticular and winged; annual, biennial, or perennial herb

2. Filament distal lobes 2, anther generally on thin stalk between lobes

3. Flower bract white-scarious, margin ± green ..... M. involucrata

3' Flower bract ± all green

4. Anther stalk between filament lobes generally < lobes; seeds narrowed at middle ..... M. tricuspis

4' Anther stalk generally >= filament lobes; seeds widest at middle

5. Upper leaves sessile; fruit erect, 13–25 mm; w Sonoran Desert ..... M. hirsutissima

5' Upper leaves petioled; fruit erect to reflexed, 9–18 mm; c Mojave Desert ..... M. tridentata

2' Filament distal lobes 0

6. Petals 8; annual ..... M. reflexa

6' Petals 5 or petals and petal-like staminodes 10; biennial or perennial herb

7. Fruit urn-shaped and gradually narrowing; seeds not winged, all filaments thread-like ..... M. torreyi

7' Fruit cup-shaped to cylindric; seeds winged; 5 outer stamens with filaments wider than thread-like

8. 5 outermost stamens with linear filaments, <= 2 mm wide, with anthers; petal tips acute; fruit 11–44 mm

9. Petals < 3 cm ..... M. inyoensis

9' Petals > 3 cm ..... M. laevicaulis

8' 5 outermost stamens with spoon-shaped to oblanceolate filaments, >= 1 mm wide, with anthers or not; petal tips acute to round or obtuse; fruit 8–18 mm

10. 5 outermost stamens without anther; petal tips acute to long-tapered ..... M. pterosperma

10' 5 outermost stamens with or without anthers; petal tips rounded to obtuse

11. Fruit generally cylindric, >= 1 cm; anthers not spiral-twisted in age ..... M. longiloba

11' Fruit cup-shaped, generally <= 1 cm; anthers spiral-twisted in age

12. Lower leaves generally entire, linear to narrowly elliptic or oblanceolate ..... M. polita

12' Lower leaves lobed to toothed, obovate to ovate, elliptic, or oblanceolate

13. Upper leaves deltate to cordate, base clasping stem ..... M. oreophila

13' Upper leaves ovate to broadly elliptic, base not clasping stem ..... M. puberula

1' Fruit < 4(5) mm wide, cylindric to obconic, if 4–5 mm wide, then obconic only; seeds irregular-rounded to irregular-angular or prism-shaped; annual

14. Seed rows 1 above mid-fruit; seeds ± prism-shaped, ×-section generally triangular with grooves along longitudinal edges

15. Outer 5 filaments widened and distally 2-lobed ..... M. micrantha

15' Outer filaments ± thread-like, not lobed

16. Lower leaves generally lobed (toothed); style 3–6.5 mm; < 1200 m ..... M. affinis

16' Lower leaves generally entire or toothed; style generally 1–3.5 mm; > 900 m ..... M. dispersa

14' Seed rows ± 3 above mid-fruit; seeds irregular-rounded to -angular (winged) above mid-fruit, below mid-fruit ×-section occasionally triangular with grooves along longitudinal edges

17. Flower bracts generally entire, green only

18. Petals generally < 8 mm

19. Seeds tan and moderately to densely mottled brown to black in age; seed coat cells pointed or domed, in age > 1/2 tall as wide on seed surface edges ..... M. albicaulis (4)

19' Seeds tan, not or sparsely mottled in age; seed coat cells flat-surfaced to domed, in age < 1/2 tall as wide on seed surface edges

20. Seed coat cells generally flat-surfaced in age ..... M. desertorum

20' Seed coat cells domed in age ..... M. obscura

18' Petals generally >= 8 mm

21. Sepals generally > 8 mm; style 7–15 mm ..... M. eremophila (2)

21' Sepals generally <= 8 mm; style 4–10 mm

22. Seeds without conspicuous recurved flap over attachment scar; seed coat cells pointed or domed, in age > 1/2 tall as wide on seed surface edges ..... M. jonesii

22' Seeds with conspicuous recurved flap over attachment scar; seed coat cells domed, in age < 1/2 tall as wide on seed surface edges ..... M. nitens

17' Flower bracts toothed to lobed or flower bracts entire with ± white base and green margin

23. Flower bracts green only

24. Styles > 15 mm

25. Petals generally 8–17 mm wide; c&s Sierra Nevada Foothills, s High Sierra Nevada ..... M. crocea

25' Petals generally 16–33 mm wide; San Joaquin Valley, e San Francisco Bay Area, n Inner South Coast Ranges ..... M. lindleyi

24' Styles < 15 mm

26. Petals generally < 8 mm

27. Petals orange to orange-yellow, base generally red to orange; flower bracts 3–7-toothed to lobed (entire); fruit generally curved < 40° ..... M. veatchiana (3)

27' Petals yellow, base generally orange; flower bracts 3-toothed to entire; fruit generally curved < 180° ..... M. albicaulis (4)

26' Petals generally >= 8 mm

28. Petals yellow only; w Mojave Desert ..... M. eremophila (2)

28' Petals orange to yellow, base red to orange; s Sierra Nevada Foothills, s San Joaquin Valley, s Outer South Coast Ranges, n Western Transverse Ranges ..... M. pectinata

23' Flower bracts ± white at base, margin green

29. Flower bracts ± concealing fruits, mostly white-scarious; inflorescence dense ..... M. congesta

29' Flower bracts not concealing fruits, ± white below middle; inflorescence open to ± dense

30. Petals generally > 8 mm, yellow, base generally orange; seed coat cells domed, in age ± 1/2 tall as wide on seed surface edges

31. Pine/oak woodland; s San Francisco Bay Area, South Coast Ranges, Western Transverse Ranges, w San Gabriel Mountains ..... M. gracilenta

31' Desert scrub, Joshua-tree woodland; San Gabriel Mountains, e Peninsular Ranges, sw Mojave Desert, w Sonoran Desert ..... M. ravenii (2)

30' Petals generally < 8 mm, orange to yellow, base generally red to orange; seed coat cells generally pointed or domed, in age > 1/2 tall as wide on seed surface edges

32. Styles generally < 3.5 mm; longest mature fruit generally > 10 mm

33. Flower bracts 3-toothed to entire; ± white base of bracts faint, small; longest mature fruit generally > 15 mm, generally curved < 180°; below 2300 m ..... M. albicaulis (4)

33' Flower bracts 3–7-toothed; ± white base of bracts prominent, generally conspicuously extending outwards from midvein; longest mature fruit generally < 17 mm, curved < 45°; 600–3400 m ..... M. montana

32' Styles generally >= 3.5 mm; longest mature fruit generally > 15 mm

34. Petals orange to orange-yellow, base generally red to orange; flower bracts 3–7-toothed to lobed (entire) ..... M. veatchiana (3)

34' Petals yellow, base generally orange; flower bracts 7-toothed to entire

35. Flower bracts 3-toothed to entire, width < 2/3 length; ± white base of bracts faint, small; fruit generally curved < 180° ..... M. albicaulis (4)

35' Flower bracts 3–7-toothed, width > 1/3 length; ± white base of bracts prominent, generally conspicuously extending outwards from midvein; fruit generally curved < 40°

36. Stem generally spreading; desert scrub, Joshua-tree woodland ..... M. ravenii (2)

36' Stem generally erect; pine/oak woodland, grassland ..... M. veatchiana (3)

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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