Sp. Pl. 2: 933. 1753.


Gen. Pl. ed. 5, 402. 1754.

Etymology: C lassic Latin name derived from Greek ion, violet
Synonyms: Chrysion Spach Crocion Nieuwland & Kaczmarek Lophion Spach
Treatment appears in FNA Volume 6. Treatment on page 111. Mentioned on page 106, 107, 108, 112, 113, 114, 122, 128, 137, 149, 154, 155, 156, 159.

Herbs, annual or perennial, caulescent or acaulescent, homophyllous (heterophyllous in V. palmata, V. sagittata, and V. septemloba), hairs concentrated or scattered throughout. Stems usually deciduous and withering at end of season, 0–5(–10+), erect to ascending, decumbent, or prostrate, simple, [woody], leafy; from horizontal or vertical, thick, fleshy or subligneous, shallow or deep-seated rhizome (caudex); or from narrow or thick rhizomes; or spreading, thin stolons; or slender taproots in annual species and seedlings; in caulescent species, short, axillary branches are sometimes present on main stems. Leaves alternate on caulescent species, simple (compound in V. beckwithii, V. douglasii, V. hallii, V. sheltonii, and V. trinervata), petiolate; caulescent plants with 0–11(–22) basal leaves per caudex, acaulescent plants with 1–12(–18) leaves per rhizome, prostrate to erect; stipules adnate to petiole or not, not leaflike (sometimes leaflike in V. lobata), unlobed, shorter than leaves (except V. arvensis, V. bicolor, and V. tricolor); blade not overlapping basally (except occasionally in V. blanda and V. rotundifolia), ovate, reniform, deltate, orbiculate, lanceolate, spatulate, or linear, adaxial surface not mottled (except in V. hastata and V. hirsutula). Inflorescences axillary (rarely umbellate in V. sagittata forma umbelliflora) from distal and proximal stem nodes in caulescent species or scapose from rhizomes or stolons in acaulescent species, 1(–3)[–5]-flowered; peduncles not jointed; bracteoles present. Flowers: sepals entire, equal or subequal, margins ciliate or eciliate, auriculate, auricles prominent or not; upper 2 and lateral 2 petals showy, 5+ mm, lowest petal showy, not narrowed at middle of limb; lateral petals and sometimes others bearded proximally with variously shaped hairs; style bearded or beardless; spur gibbous or elongated; stamens connivent, but distinct, forming cone around ovary, not adherent to style, dehiscing introrsely, lower 2 filaments spurred with nectary that protrudes into petal spur; cleistogamous flowers absent or produced in summer, apetalous or petals 0 or 2(–3) and scarcely developed, stamens 2, usually adherent to style. Capsules ovoid, ellipsoid, oblong, spherical, or subglobose, glabrous, puberulent, or tomentose, sometimes muriculate. Seeds 6–75, spherical or ovoid, glabrous, often arillate with elaiosome. x = 6, 7.


Nearly worldwide, temperate regions, also South America, Pacific Islands (Hawaii, Philippines, Taiwan).


The taxonomy of Viola is often considered difficult partly because of hybridization; more than 100 named hybrids occur in the flora area. Hybrids among the blue-flowered, acaulescent species in eastern North America and among other species are well known (E. Brainerd 1924; N. H. Russell and M. Cooperrider 1955; G. L. Stebbins et al. 1963; T. S. Cooperrider 1986; L. E. McKinney 1992; H. E. Ballard 1993, 1994; A. Haines 2011).

Other factors contribute to phenotypic variation. The dimensions of leaves and stems often increase substantially between early spring and late summer (D. Klaber 1976). Stem, leaf, and flower size vary with environmental factors such as aspect, light, available soil moisture, and other edaphic conditions (Klaber; L. E. McKinney 1992).

The number of recognized taxa and the ranks attributed to taxa vary among authors (E. Brainerd 1921; N. H. Russell 1965; L. E. McKinney 1992; H. E. Ballard 1994; N. L. Gil-Ad 1997; D. B. Ward 2006).

An effort to deal with the difficulties encountered, specifically with subsect. Boreali-Americanae (W. Becker) Gil-Ad, was made by N. L. Gil-Ad (1997, 1998). Much of his species; we do not share his conclusions about some species, such as Viola hirsutula and V. subsinuata.

We do not present an infrageneric classification for Viola here. Some species complexes have been identified (for example, V. adunca, canadensis, nuttallii, palustris, and purpurea). W. Becker (1925) provided the first infrageneric classification, which was largely followed by G. K. Brizicky (1961b), a scheme largely based on style morphology. For the most part, this classification continues to be followed (T. Marcussen and T. Karlsson 2010); some of the names used to refer to species complexes (for example, Nuttallianae) were published without rank and have been incorrectly assumed to be subsections [for example, J. Clausen (1964); Marcussen and Karlsson]. Chen Y. S. et al. (2007) replaced sections with subgenera.

Branching of stems in perennial caulescent North American Viola species is uncommon and has been documented in ten species: V. adunca, V. canadensis, V. canina, V. douglasii, V. glabella, V. pedunculata, V. pinetorum, V. purpurea, V. quercetorum, and V. walteri. Branching in these species involves the development of one or more relatively short, leafy, axillary shoots on one or more stems.

The three annual species in the flora area, V. arvensis, V. bicolor, and V. tricolor, commonly branch from the base of the main stem near or at the crown and from nodes higher on the stem.

The leaves of acaulescent species develop from the rhizome. In homophyllous plants, all leaf blades are lobed from early season through late season; the depth of sinuses depends somewhat on the age of the plant. In heterophyllous plants, the earliest leaf blades are not lobed; later-season blades are lobed. E. Brainerd (1910, 1921) placed great emphasis on these morphological distinctions to differentiate Viola taxa. Like Brainerd, L. E. McKinney (1992) found these differences to be reliable taxonomic characters.

Here, the distal portion of the style is called the style head. The shape, size, position of the stigmatic surface, and degree of bearding vary among species. Differences among style heads have been used in Viola classification (W. Becker 1925; J. Clausen 1929) and in keys. Here, we report whether the style head is bearded or beardless based on reports in the literature and our observations. Of the 30 acaulescent species in the flora area, one has a bearded style; of the 43 caulescent species, 35 are always bearded, three are bearded or beardless, and five are always beardless.

Of the 73 species of Viola in the flora area, 60 are known to produce cleistogamous flowers, nine do not, and the condition in four is unknown. In some species of acaulescent A. Mayers and E. Lord (1983, 1983b) reported that pollen grains in cleistogamous flowers of V. odorata germinate in the undehisced anther sacs; the pollen tubes then penetrate the sac and grow towards the stigma. In other groups, observations suggest that pollen is released in proximity to the recurved style (T. Marcussen and T. Karlsson 2010).

Substantial research has been conducted on Viola pollination including cleistogamous flowers (A. J. Beattie 1969, 1969b, 1971, 1972, 1974, 1976, 1978; Beattie and D. C. Culver 1979; A. C. Cortés-Palomec and H. E. Ballard 2006; T. M. Culley 2000, 2002; G. Davidse 1976; L. Freitas and M. Sazima 2003; C. M. Herrera 1990; A. Mayers and E. Lord 1983, 1983b). Pollinator rewards available in most Viola flowers include nectar and pollen.

Pollinators of violets include bumblebees, honeybees, solitary bees, syrphid flies, butterflies, skippers, hawkmoths, moths, and beeflies. Thrips have been reported in Viola flowers (M. S. Baker 1935) and while these insects are often observed with pollen attached to their bodies, there is currently no evidence they play a role in pollination of Viola. Due to the high frequency that thrips, aphids, and other minute insects with pollen on their bodies have been observed in Viola flowers, it seems probable that these insects sometimes effect pollination.

The three valves of Viola capsules usually are thick in perennial species and thin in annual species. The capsules of at least some species open relatively slowly, exposing the seeds. As the valves dry, they contract and squeeze the seeds causing them to be ejected (R. J. Little and G. Leiper 2012). Capsules that disperse seeds ballistically are usually on erect peduncles; capsules that passively release their seeds usually point downward (A. J. Beattie and N. Lyons 1975).

Most Viola seeds possess an outgrowth (elaiosome), or food body, of variable size that is often attractive to ants. S. Lengyel et al. (2010) estimated that over 70% of Violaceae species are myrmecochorous. Studies have been conducted on various aspects of myrmecochory in Viola (A. J. Beattie and N. Lyons 1975; R. Y. Berg 1975; D. C. Culver and Beattie 1978, 1980; Beattie and Culver 1981; G. Matlack 1994).

Violets of horticultural importance include Viola arvensis (field or wild pansy), V. odorata (English or sweet violet), V. tricolor (Johnny-jump-up), and V. ×wittrockiana Gams ex Nauenburg & Buttler (garden pansy). Over 120 species of Viola are grown as ornamentals (L. Watson and M. J. Dallwitz,

E. Brainerd (1908) reported that Viola chinensis G. Don (= V. patrinii de Candolle ex Gingins) was established at the New York Botanical Garden, at a residence in the District of Columbia, and in his garden in Massachusetts. It appears not to have persisted; it was not mentioned by N. Taylor (1915). A. Haines (2011) noted that reports of V. chinensis in New England were based on misidentifications of V. japonica.

Native Americans in the United States and Canada used Viola species for drugs, dyes, and food (D. E. Moerman 1998). Medicinal uses included pain relief and treatment of ailments including colds and coughs and for dermatological, gastrointestinal, eye, heart, and respiratory problems. Leaves and stems of some species were used as vegetables, usually cooked. Some tribes are reported to have soaked the seeds of corn in an infusion of violet roots before planting to repel insects.

Mature plants are often needed for identification of violets. In preparing specimens of violets, care should be taken to record data on petal and spur colors, and presence and distribution of beards on lateral and other petals, or note if lacking.

Measurements of the lowest petal in the descriptions here include the spur.

When this treatment was being finalized, Viola calcicola R. A. McCauley and H. E. Ballard was described as new. Time constraints prevented it from being incorporated. Viola calcicola is acaulescent, heterophyllous, has short, vertical rhizomes, nearly white to purple corollas, and occurs only on limestone substrates. It is endemic to the Guadalupe Mountains of Texas and New Mexico.

Species 400–600 (73 in the flora).

Selected References


1 Plants acaulescent > 2
1 Plants caulescent > 34
2 Style head bearded; Arizona. Viola umbraticola
2 Style head beardless; not confined to Arizona > 3
3 Petals deep lemon-yellow. Viola rotundifolia
3 Petals not lemon yellow > 4
4 Leaf blades lobed > 5
4 Leaf blades unlobed (mid-season incised or lobed at base only in V. sagittata) > 13
5 Leaf blades lobes similar in width and shape > 6
5 Middle and lateral blade lobes differ in width and/or shape > 7
6 All petals beardless; cleistogamous flowers absent. Viola pedata
6 Lateral petals bearded, lowest sometimes bearded; cleistogamous flowers present. Viola pedatifida
7 Mid-season leaf blades incised or lobed at base only. Viola sagittata
7 Mid-season leaf blades incised or lobed throughout > 8
8 Earliest leaf blades lobed (plants homophyllous), similar to mid-season blades > 9
8 Earliest leaf blades unlobed, or sometimes 3-lobed (plants heterophyllous), mid-season blades lobed > 10
9 Middle lobes of leaf blades lanceolate or spatulate to narrowly obovate; plants usually glabrous; sepal auricles 2–3 mm. Viola brittoniana
9 Middle lobes of leaf blades narrowly deltate to narrowly elliptic; plants usually pubescent; sepal auricles 1–2 mm. Viola subsinuata
10 Mid-season leaf blades with 3–5 primary lobes, middle lobe elliptic, ovate, to widely ovate. Viola palmata
10 Mid-season leaf blades with 5–9 primary lobes, middle lobe lanceolate, spatulate, to narrowly ovate > 11
11 Petioles, leaf surfaces, and peduncles rarely glabrous. Viola palmata
11 Petioles, leaf surfaces, and peduncles rarely pubescent > 12
12 Earliest leaf blades ± deltate or 3-lobed; lowest petal 10–15 mm; plants of limestone glades and barrens. Viola egglestonii
12 Earliest leaf blades ± ovate, sometimes 3-lobed; lowest petal 15–25 mm; plants of sandy, dry or seasonally wet pine or mixed pine-deciduous woods. Viola septemloba
13 Lowest petal spur 3–10 mm > 14
13 Lowest petal spur 1–3 mm > 17
14 Capsules puberulent. Viola odorata
15 Petioles not winged. Viola selkirkii
15 Petioles narrowly winged distally > 16
16 Leaf base cordate. Viola japonica
16 Leaf base usually truncate, sometimes ± cordate or broadly cuneate. Viola prionantha
17 Leaf blades lanceolate, narrowly elliptic, linear, or ovate > 18
17 Leaf blades ovate to broadly ovate, reniform, orbiculate, elliptic, or deltate > 19
18 Leaf blades lanceolate or narrowly elliptic to nearly linear. Viola lanceolata
18 Leaf blades elliptic to narrowly or broadly ovate. Viola primulifolia
19 Plants stoloniferous > 20
19 Plants not stoloniferous > 23
20 Petals white > 21
20 Petals lilac, pale blue, violet, or deep purple, sometimes nearly white > 22
21 Lateral petals usually beardless; leaf blade margins serrate, ciliate or eciliate. Viola blanda
21 Lateral petals usually bearded, rarely beardless; leaf blade margins ± entire or shallowly crenate, eciliate. Viola macloskeyi
22 Bracteoles usually above middle of peduncle in chasmogamous flowers; leaf blade margins crenate, denticulate, or entire, ciliate or eciliate. Viola epipsila
22 Bracteoles usually below middle of peduncle; leaf blade margins crenulate, eciliate. Viola palustris
23 All petals beardless > 24
23 Lateral 2 and sometimes also lowest petals bearded > 25
24 Petals light violet on both surfaces; leaf blades ± deltate. Viola clauseniana
24 Petals white on both surfaces; leaf blades reniform or ovate to broadly ovate or orbiculate. Viola renifolia
25 Petals white. Viola renifolia
25 Petals violet, light to dark blue-violet, lavender-violet, light to deep or dull reddish violet, dark purple-violet or reddish purple, or deep bluish violet, rarely white > 26
26 Sepal auricles 2–6 mm > 27
26 Sepal auricles 1–2 mm > 28
27 Leaf blade base reniform to cordate; plants of mesic to wet habitats. Viola cucullata
27 Leaf blade base truncate, slightly sagittate or hastate, or ± cordate; plants of dry, sandy, open woods and thickets. Viola sagittata
28 Adaxial leaf surface with silvery strigose patches. Viola hirsutula
28 Adaxial leaf surface without silvery strigose patches > 29
29 Petioles densely pubescent > 30
29 Petioles glabrous or pubescent > 31
30 Leaf blades narrowly ovate to narrowly deltate; plants of wet, rocky shores of lakes and streams, meadows. Viola novae-angliae
30 Leaf blades elliptic, ovate, or reniform; plants of sandy pine-oak or pine-oak-hickory woods and disturbed ground. Viola villosa
31 Leaf blades ovate, broadly ovate, or reniform to broadly reniform or orbiculate > 32
31 Leaf blades narrowly ovate or narrowly deltate to broadly deltate > 33
32 Leaf blades somewhat fleshy, surfaces usually glabrous, grayish green or purplish green abaxially; plants of wet habitats in saturated soil; plants 5–15 cm. Viola nephrophylla
32 Leaf blades not fleshy, surfaces usually pubescent, green abaxially; plants of dry or mesic habitats, not in saturated soil; plants 5–50 cm. Viola sororia
33 Leaf blades sparsely pubescent, rarely glabrous adaxially; lower petal obviously bearded, rarely beardless. Viola affinis
33 Leaf blades glabrous, rarely pubescent; lower petal beardless, rarely lightly bearded. Viola missouriensis
34 Cauline stipules palmately lobed or pinnatifid, equaling leaf blade > 35
34 Cauline stipules unlobed, shorter than leaf blade > 37
35 Lateral petals ± equaling or shorter than sepals. Viola arvensis
35 Lateral petals longer than sepals > 36
36 Sepal auricles 0.5–2 mm; style head bearded; cleistogamous flowers axillary. Viola bicolor
36 Sepal auricles 2–4 mm; style head beardless; cleistogamous flowers absent. Viola tricolor
37 Leaves compound > 38
37 Leaves simple > 42
38 Upper 2 and lower 3 petals light golden- to deep lemon-yellow > 39
38 Upper 2 petals dark reddish violet, lower 3 lilac, pale yellow, or cream, seldom white > 40
39 Leaf blades ovate, lobes 1–2.5(–5) mm wide; cleistogamous flowers absent; capsules glabrous. Viola douglasii
39 Leaf blades reniform or ovate to ± orbiculate, lobes 2–10 mm wide; cleistogamous flowers axillary; capsules glabrous or puberulent. Viola sheltonii
40 Lower 3 petals pale yellow, cream, or ± white. Viola hallii
40 Lower 3 petals lilac, rarely white > 41
41 Abaxial leaf surface without distinct vein parallel to each margin, margins usually ciliate, surfaces usually puberulent; California, Idaho, Nevada, Oregon, Utah Viola beckwithii
41 Abaxial leaf surface usually with distinct vein parallel to each margin, margins eciliate, surfaces glabrous; Oregon, Washington. Viola trinervata
42 Plants stoloniferous; stems prostrate, spreading > 43
42 Plants not stoloniferous; stems erect, ascending, spreading, decumbent, or prostrate (sometimes later reclining to nearly prostrate in V. adunca, V. howellii) > 44
43 Petals lemon-yellow; cauline stipule margins entire or sparingly toothed. Viola sempervirens
43 Petals pale to bluish violet; cauline stipule margins laciniate. Viola walteri
44 Petals white or cream adaxially > 45
44 Petals not white or cream adaxially (sometimes almost white in V. frank-smithii; rarely white in V. adunca and V. labradorica) > 48
45 Basal leaf blades orbiculate-ovate to deltate, usually shiny, leathery, base cuneate; cauline blade base cuneate Viola cuneata
45 Basal leaf blades ovate to reniform or deltate, not shiny or leathery, base cordate, subcordate, rounded, hastate, attenuate (oblique or not), or truncate; cauline blade base cordate to truncate > 46
46 Petals white or cream on both surfaces, without yellow patch basally, spur white, 3–6 mm. Viola striata
46 Petals white on adaxial surface, with yellow patch basally, spur white, yellow, or greenish, 1–2.5 mm > 47
47 Spurs white, upper 2 petals, sometimes lower 3, usually tinged soft reddish violet, rarely white abaxially. Viola canadensis
47 Spurs yellow or greenish, upper 2 petals, sometimes lower 3, deep reddish violet abaxially. Viola ocellata
48 Petals blue to gray, violet to pale or soft blue-violet, pale to deep lavender-violet, soft reddish violet, or ± white adaxially > 49
48 Petals yellow adaxially > 58
49 All petals yellow basally > 50
49 All or just 3 lower petals white basally > 51
50 Leaf blades broadly reniform to ovate, base cordate; petals soft reddish violet; lowest petal 10–15 mm, spur yellow; Washington. Viola flettii
50 Leaf blades broadly ovate, deltate, or broadly deltate, base cordate to truncate; petals blue to pale violet; lowest petal 5.5–11 mm, spur white to pale violet; Nevada, Utah. Viola lithion
51 Spurs 10–20 mm; petals beardless; style head beardless. Viola rostrata
51 Spurs 1.6–8 mm; lateral petals sparsely to densely bearded; style head bearded or beardless > 52
52 Lateral and upper 2 petals pale purple or almost white adaxially, violet abaxially; Utah. Viola frank-smithii
52 Lateral and upper 2 petals similar color on both surfaces; not limited to Utah > 53
53 Basal leaves absent. Viola canina
53 Basal leaves present > 54
54 Spurs 2–5 mm, tip straight > 55
54 Spurs 3–8 mm, tip straight, curved, or pointed, hooked > 56
55 Sepal margins ciliate or eciliate; style head bearded; seeds light brown. Viola howellii
55 Sepal margins eciliate; style head usually beardless, sometimes bearded; seeds dark olive to ± black. Viola langsdorffii
56 Sepal auricles enlarged in fruit. Viola riviniana
56 Sepal auricles not enlarged in fruit > 57
57 Leaf blades usually decurrent on petiole; cauline stipule margins lacerate to laciniate. Viola adunca
57 Leaf blades not decurrent on petiole; cauline stipule margins ± entire or laciniate. Viola labradorica
58 Stems leafless proximally, leafy distally; style head bearded > 59
58 Stems leafy proximally and distally; style head bearded or beardless > 63
59 Cauline leaf blades widely or narrowly hastate to ovate, unlobed, usually mottled light green adaxially. Viola hastata
59 Cauline leaf blades ovate, reniform, deltate, rhombic, ovate-orbiculate, or reniform-cordate, unlobed or 3–12-lobed, if deltate, not mottled light green adaxially > 60
60 Petals lemon-yellow on both surfaces; cauline blades unlobed > 61
60 Petals lemon-yellow adaxially, upper 2 and sometimes lateral 2 brownish purple abaxially; cauline blades unlobed or 3–12-lobed > 62
61 Cauline stipules ovate to oblong, margins erose or subserrate, often glandular, apex acute to acuminate; petioles 0.2–2.9 cm; blades ovate to deltate, base cordate to truncate, apex acute; Alberta, British Columbia, Alaska, California, Idaho, Montana, Oregon, Washington. Viola glabella
61 Cauline stipules ovate, margins entire or coarsely serrate or erose, apex acute; petioles 1–10 cm; blades reniform or ovate to ovate-orbiculate or deltate, base cordate, apex acute to acuminate; c (incl. Wyoming), e North America. Viola pubescens
62 Stems 1–3; basal leaves 0–2; cauline stipules sometimes ± leaflike; peduncles 2–13 cm; California, Oregon. Viola lobata
62 Stems 1(–2); basal leaves 0(–2); cauline stipules not leaflike; peduncles 1.5–4 cm; e United States. Viola tripartita
63 Basal leaves 0; style head bearded > 64
63 Basal leaves 1–11; style head bearded or beardless > 65
64 Petioles glabrous; leaf blades 1.2–2.4 cm, margins entire or with 1–3 crenations on proximal 1/2, eciliate; Texas. Viola guadalupensis
64 Petioles usually finely puberulent, sometimes glabrate; leaf blades 1–5.5 cm, margins crenate to serrate, ciliate; California. Viola pedunculata
65 Style head beardless. Viola biflora
65 Style head bearded > 66
66 Cleistogamous flowers absent. Viola tomentosa
66 Cleistogamous flowers present > 67
67 Capsules puberulent > 68
67 Capsules glabrous or finely puberulent > 71
68 Basal blade with prominent whitish veins adaxially; seeds black. Viola charlestonensis
68 Basal blade without prominent whitish veins adaxially; seeds light to medium or dark brown or mottled gray and brown > 69
69 Capsules 8–12 mm. Viola quercetorum
69 Capsules 3.5–7 mm > 70
70 Cauline blades 2.8–9.6 × 0.3–1.4 cm, length 4–11 times width. Viola pinetorum
70 Cauline blades 0.9–5.2 × 0.2–2.9 cm, length 0.8–7.1 times width. Viola purpurea
71 Capsules ellipsoid to oblong > 72
71 Capsules spherical, subglobose, or ovoid > 73
72 Base of basal and cauline leaf blades cordate; upper 2 petals deep lemon-yellow abaxially.Viola orbiculata > 72
72 Base of basal and cauline leaf blades attenuate to ± truncate or subcordate; upper 2 petals brownish purple abaxially. Viola praemorsa
73 Basal leaf base usually truncate, sometimes attenuate. Viola vallicola
73 Basal leaf base attenuate (rarely truncate or subcordate in V. utahensis) > 74
74 Basal blade margins ± coarsely crenate-serrate. Viola utahensis
74 Basal blade margins entire or serrulate, sometimes with a few sharp teeth or crenulate > 75
75 Elaiosome not covering funiculus; basal and cauline leaf surfaces glabrous or puberulent on margins or veins. Viola bakeri
75 Elaiosome completely covering funiculus; basal and cauline leaf surfaces glabrous or puberulent. Viola nuttallii
... more about "Viola"
R. John Little +  and Landon E. McKinney† +
Linnaeus +
Nearly worldwide +, temperate regions +, also South America +, Pacific Islands (Hawaii +, Philippines +  and Taiwan). +
C lassic Latin name derived from Greek ion, violet +
Sp. Pl. +  and Gen. Pl. ed. +
1753 +  and 1754 +
baird1942a +, ballard1992a +, ballard1998a +, beattie1975a +, fabijan1987a +, gil-ad1997a +, gil-ad1998a +, klaber1976a +, marcussen2012a +, mckinney1992a +  and russell1965a +
Chrysion +, Crocion +  and Lophion +
Violaceae +