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Leaf: generally deciduous.
Flower: sepals ± equal, entire; petals unequal, lowest generally largest, with spur generally < 3 [20] mm, lateral 2 equal, generally spreading, upper 2 equal, erect or reflexed, overlapped or not, lateral 2 generally, others sometimes with beard of variously shaped hairs basally; cleistogamous flowers generally present, petals 0.
Fruit: ovoid to oblong, hairy or not.
Seed: 8–75.
± 500 species: temperate, worldwide, HI, Andes. (Latin: classical name) Important orns including Viola odorata, Viola tricolor L. (Johnny-jump-up, wild pansy), Viola ×wittrockiana Gams (garden pansy).
Unabridged references: [Baker, M.S. 1949a. Studies in western violets. IV. Leafl. West. Bot. 5: 141–147; Baker, M.S. 1949b. Studies in western violets. VI; Madroño 10: 110–128; Baker, M.S. 1957. Brittonia 9: 217–230; Ballard, H.E. 1992. Systematics of Viola Section Viola in North Am north of Mexico. M.S. thesis, Central Michigan University, Mt. Pleasant, Michigan; Ballard, H.E. 1994. Violets of Michigan. Michigan Botanist 33: 131–199; Davidse, G. 1976. A study of some Intermountain violets (Viola Sect. Chamaemelanium). Madroño 23: 274–283; Fabijan et al. 1987. The taxonomy of the Viola nuttallii complex. Can. J. Bot. 65: 2562–2580; Gil-Ad, N.L. 1995. Systematics and evolution of Viola L. subsection Boreali Americanae (W. Becker) Brizicky. Ph.D. dissertation, Univ of Michigan, Ann Arbor, Michigan; Gil-Ad, N.L. 1997. Systematics of Viola subsection Boreali-Americanae. Boissiera 53: 1–130; Hitchcock, C.L. 1961. Vasc. Plant. Pacific NorthW. Vol. 3; McKinney, L.E. 1992. A taxonomic revision of the acaulescent blue violets (Viola) of North Am. Sida Botanical Miscellany, 7: 1–59; McKinney, L.E. and N. Russell. 2002. Violaceae of the Southeastern United States. Castanea 4: 369–379; Russell, N.H. 1965. Violets (Viola) of the central and eastern United States: an introductory survey. Sida 1: 1–113]

Key to Viola

1. St 0, internodes 0

2. Rhizomes thick, fleshy; plants without stolons ..... V. nephrophylla

2' Rhizomes thin, not fleshy; plants with stolons, at least in summer

3. Fr puberulent; leaf blade crenate; stolons green, leafy ..... V. odorata

3' Fr glabrous; leaf blade crenate to serrate; stolons pale, not leafy

4. Lf blade lanceolate, narrowly ovate, or elliptic; petals white ..... V. primulifolia subsp. occidentalis

4' Lf blade reniform, ovate, or round; petals white or lilac to pale blue or ± white, with purple lines

5. Lf blade glabrous to coarsely hairy; petals white; plants in dense patches ..... V. macloskeyi

5' Lf blade generally glabrous; petals lilac, pale blue, or ± white; plants not in dense patches ..... V. palustris

1' St present, internodes short or long

6. Stipules ± = leaf; annual; lateral petals = or generally < sepals ..... V. arvensis

6' Stipules << leaf; perennial herb; lateral petals >>sepals

7. Lvs compound

8. Petals of 1 color, light gold- or deep lemon-yellow; cleistogamous flowers present or 0

9. Lf blades longer than wide; leaf segments 3–5, 1–2.5(5) mm wide; cleistogamous flowers 0; lateral 2 petals bearded with cylindric hairs ..... V. douglasii

9' Lf blades wider than long; leaf segments 3, 2–10 mm wide; cleistogamous flowers present, exclusively or not; lateral 2 petals ± bearded or not with club-shaped hairs ..... V. sheltonii

8' Petals of 2 colors, upper dark red-violet, lower lilac, pale yellow, or cream to ± white; cleistogamous flowers 0

10. Lower 3 petals (apart from veins, spots) lilac to ± white; leaves generally puberulent (glabrous) ..... V. beckwithii

10' Lower 3 petals (apart from veins, spots) pale yellow, cream, or ± white, deep yellow to orange basally; leaves glabrous except veins, margins generally ciliate, stipules occasionally ciliate ..... V. hallii

7' Lvs simple

11. Lower stem erect, without leaves, peduncles

12. Upper 2 petals deep lemon-yellow abaxially; stem green; cauline leaf ovate to deltate, entire; moist to wet generally shady places ..... V. glabella

12' Upper 2 petals dark red-brown abaxially; stem generally purple; cauline leaf reniform, deltate, ± ovate, or diamond-shaped, deeply divided or not; generally dry shady or open places ..... V. lobata

13. Cauline leaf diamond-shaped, reniform-cordate, or generally deltate, not lobed or dissected ..... subsp. integrifolia

13' Cauline leaf ± ovate, deltate, or generally reniform, palmately lobed or deeply dissected ..... subsp. lobata

11' Lower stem prostrate to erect, with leaves, peduncles

14. Plant with stolon-like stem; leaves evergreen ..... V. sempervirens

14' Plant without stolon-like stem; leaves deciduous

15. Petals white at least adaxially, lateral with large purple spot basally above smaller yellow area

16. Lf generally shiny, cauline leaf base wedge-shaped; plant glabrous ..... V. cuneata

16' Lf not shiny, cauline leaf base ± cordate to truncate; plant ± glabrous to generally puberulent ..... V. ocellata

15' Petals not white

17. Petals light to deep violet, lavender, or blue-violet

18. Rhizome fleshy; style head glabrous; sepals not ciliate ..... V. langsdorffii

18' Rhizome woody; style head bearded; sepals ciliate or not

19. Lf ovate to ovate-triangular, entire to crenate; sepals not ciliate; spur generally longer than wide, straight or tip hooked; CA-FP, Wrn ..... V. adunca subsp. adunca

19' Lf ovate to reniform, crenate; sepals ciliate or not; spur ± as long as wide, straight, tip not hooked; KR (near Joe Bar, Siskiyou Co.) ..... V. howellii

17' Petals yellow to orange

20. Petals gold-yellow, lowest 10–20 mm; basal leaf 0 per caudex; cleistogamous flower 0 ..... V. pedunculata

20' Petals deep lemon-yellow, lowest 6–16 mm; basal leaf 1–6 per caudex; cleistogamous flower present (0 in Viola tomentosa)

21. Fr glabrous to minutely puberulent

22. Basal leaf blade base generally ± truncate ..... V. praemorsa subsp. praemorsa

22' Basal leaf blade base generally tapered, obliquely so or not

23. Lf generally entire ..... V. bakeri

23' Lf ± entire, ± crenate, serrate, wavy, or generally irregularly toothed ..... V. praemorsa subsp. linguifolia

21' Fr puberulent to tomentose

24. Basal leaves entire; cleistogamous flowers 0; fruit tomentose; n-c SNH ..... V. tomentosa

24' Basal leaves not entire (Viola purpurea subsp. integrifolia, Viola pinetorum subsp. pinetorum occasionally entire); cleistogamous flowers present; fruit puberulent

25. Lvs canescent to tomentose

26. Basal leaves oblanceolate to obovate or generally linear to narrowly lanceolate, canescent to gray-tomentose; s SNH, Teh, WTR, SnBr ..... V. pinetorum subsp. grisea

26' Basal leaves oblong, ovate, or round, green-tomentose; SNE, DMoj ..... V. purpurea subsp. aurea

25' Lvs ± glabrous to puberulent

27. Sts mostly buried, not much elongated by end of season; plant 3–8.5(12) cm

28. Cauline leaves generally entire, puberulent; basal leaves ± crenate to irregularly shallowly dentate or entire, unlobed; NW, CaR, n&c SNH ..... V. purpurea subsp. integrifolia

28' Cauline leaves coarsely crenate or dentate, ± glabrous; basal leaves coarsely serrate or generally irregularly dentate or crenate with 2–4 rounded lobes per side; NCoRH, NCoRI, SnGb, GB, DMtns (Panamint Range) ..... V. purpurea subsp. venosa

27' Sts generally not buried, generally elongated by end of season; plant 3–25(34.5) cm

29. Basal leaf bases cordate to truncate

30. Basal leaf generally gray-green, occasionally purple-tinted abaxially

31. Basal leaf with 4–5(6) prominent lobes per side; TR, PR, SNE, DMoj ..... V. purpurea subsp. mohavensis (3)

31' Basal leaf without prominent lobes; CaR, SN, CW, SW, MP ..... V. purpurea subsp. quercetorum (2)

30' Basal leaf generally purple-tinted, occasionally gray-green abaxially

32. Cauline leaf not prominently lobed; basal petiole 1.8–8.5 cm; peduncle 4.6–6 cm; n SNH, GB ..... V. purpurea subsp. dimorpha

32' Cauline leaf with 3–4(5) prominent lobes per side; basal petiole 4.5–14.5 cm; peduncle 1.7–14 cm; TR, PR, SNE, DMoj ..... V. purpurea subsp. mohavensis (3)

29' Basal leaf bases tapered

33. Basal leaf generally gray-green, occasionally purple-tinted abaxially ..... V. purpurea subsp. quercetorum (2)

33' Basal leaf generally purple-tinted abaxially

34. Cauline leaf 2–10 × longer than wide

35. Cauline leaf blade 3.5–9.6 cm, serrate or dentate with 2–4 short projections per side to ± entire; CaR, SN, WTR, SnBr, SnJt ..... V. pinetorum subsp. pinetorum

35' Cauline leaf blade 1.5–4.8 cm, wavy, shallowly dentate, sharp-angled, or entire; CaR, SNH, WTR, SnBr, SnJt ..... V. purpurea subsp. mesophyta

34' Cauline leaf generally < 2 × longer than wide

36. Basal leaf with 4–5(6) prominent lobes per side, not shiny adaxially; TR, PR, SNE, DMoj ..... V. purpurea subsp. mohavensis (3)

36' Basal leaf without prominent lobes, occasionally shiny adaxially; NW, CaR, SN, CW, SW, MP ..... V. purpurea subsp. purpurea

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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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