Herbs perennial or biennial, rarely subshrubs, rhizomatous. Stem developed or absent, sometimes with creeping branches. Leaves simple, alternate or basal, margin entire, dentate, or dissected; stipules small or large, leaflike, free or ± adnate to petioles. Flowers bisexual, zygomorphic, solitary, often dimorphic (cleistogamous flowers later than chasmogamous ones); pedicels axillary, 2-bracteolate. Sepals slightly equal, usually basally auriculate. Petals unequal, anterior petal largest and basally spurred. Filaments free, very short; anthers free or mostly connivent into a sheath around ovary, 2 anterior ones with spurlike or wartlike and nectariferous appendages at base, these extending into anterior spur, connectives produced apically into conspicuous, membranous appendages. Ovary 3-carpelled, with many ovuled parietal placentae; styles nearly erect or usually ± curved downward, ± thickened or sometimes gradually tapering toward apex, entire or variously appendaged; style apex and stigma variously shaped. Capsule loculicidally and elastically 3-valved, valves carinate and abaxially thickened. Seeds globose-ovoid, arillate or not, usually smooth; endosperm abundant; embryo straight; cotyledons rather thick, plano-convex.
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.
Herbs, annual or perennial, rarely suffrutices, often acaulescent. Leaves al- ternate, petiolate, the stipules sometimes foliaceous, persistent. Flowers axillary, usually solitary, zygomorphic, often dimorphous (cleistogamous flowers following chasmogamous ones); pedicels not articulated; sepals subequal, usually basally auricled; petals spreading, unequal, the anterior petal the largest and basally cal- carate; filaments very short, free; anthers free or mostly connivent into a sheath around the ovary, the 2 anterior ones with spur-like or wart-like, nectariferous ap- pendages at the base, these extending into the spur of the anterior petal, the con- nectives produced apically into conspicuous, membranous appendages; ovary with 3 oo-ovulate placentae; style almost erect or usually ? curved downwards, -+ thick- ened or sometimes gradually tapering towards the apex, entire or variously ap- pendaged, the style apex and stigma variously shaped. Capsules loculicidally and elastically 3-valvate, the valves carinate and dorsally thickened; seeds globose- ovoid, arillate or not, usually smooth; endosperm abundant; embryo straight; cotyledons rather thick, plano-convex.
"Sep usually with posterior auricles; pet somewhat unequal, the 2 lateral ones often bearded internally at the base, the lower one usually with a basal spur or sac and sometimes bearded at the throat; stamens 5, the 2 lowermost bearing appendages that extend into the spur of the lower pet; ours herbs with axillary or basal 1-fld peduncles bearing 2 small bracts near the middle. Most spp. produce normal petaliferous fls in spring, and very fertile cleistogamous fls in summer. All spp. with cyanic (rather than yellow) fls produce occasional white-fld forms. Hybrids between closely related spp. are common, and spp. 3–8 form an intergrading polyploid complex. 400, mainly N. Temp."
Ovary generally with numerous ovules; style usually deflexed downwards and thickened towards the tip
Stamens with very short free filaments and free or slightly coherent anthers; connective-appendages entire, generally oblong or ovate; lower 2 anthers each with an appendage extending into the spur and which excretes nectar
Seeds usually smooth, with or without an aril.
Fruit a loculicidal capsule with 3 contractile valves
Flowers solitary, axillary, zygomorphic; pedicels with a pair of small bracteoles, generally above the middle
Petals unequal, the lowermost (the lip) usually larger, sometimes equal to or smaller than the other petals and with a short or long basal spur directed backwards
Sepals ± equal, usually with a short basal appendage
Leaves alternate, peiolate; stipules entire to variously toothed or lobed, sometimes foliaceous
Stamens with very short free filaments; anthers free or slightly coherent, with a ± thick dorsal prolongation of the connective ("connective-appendage"), and the ventral anthers with two appendages which extend into the spur and secrete nectar ("spur-appendages").
Seeds globose-ovoid, usually smooth, with abundant endosperm and with or without a thickened aril.
Fruit a loculicidal capsule with 3 contractile valves keeled and thickened along the sutures.
Ovary with 3 placentas, each bearing numerous ovules; style usually bent downwards and ± thickened towards the apex, entire or with various appendages; stigma terminal, or apparently lateral when the style apex is reflexed.
Sepals almost equal, usually with a basal appendage (± absent in V. abyssinica).
Petals unequal, the anterior usually larger than the others with a basal spur of varying length, blue or purple to yellow or white but always yellow at the base.
Leaves alternate, petiolate, usually ± serrate; stipules sometimes foliaceous, persistent.
Inflorescence almost always of single flowers in the leaf axils; pedicels not articulated.
Herbes'à sous-arbustes.'Feuilles'alternes, pétiolées, généralement crénelées à serrées-dentées; stipules souvent foliacées et laciniées, persistantes.'Fleurs'à pédicelle non articulé, axillaires, solitaires, zygomorphes, parfois dimorphes, les unes ☿ et souvent stériles, les autres cléistogames, plus petites, apétales et fertiles; sépales subégaux, généralement avec appendice basal; pétales inégaux, dissemblables, l'antérieur en général plus grand et pourvu à la base d'un éperon ou d'un appendice sacelliforme, bleus, mauves ou blancs, mais toujours jaunes à la base; étamines à filets libres très courts, les 2 antérieures à filet éperonné; anthères libres ou un peu cohérentes; connectif appendiculé au sommet; anthères antérieures à appendice basal glanduleux dirigé vers le bas, logé dans l'éperon de la fleur; ovaire 1-loculaire, à 3 placentas multiovulés; style généralement courbé à la base et élargi vers le sommet; stigmate terminal ou apparemment latéral.'Capsules'loculicides, à 3 valves contractiles, carénées, épaissies le long de la suture, papyracées.'Graines ovoïdes-ellipsoïdes, généralement lisses, avec ou sans arille épaissi.\n\t\t\t\tGenre cosmopolite comprenant 400 à 500 espèces, croissant principalement dans les régions tempérées de l'hémisphère Nord. Certaines espèces sont présentes dans les montagnes de l'hémisphère Sud. Pour la Flore, 2 espèces limitées aux régions montagneuses orientales.
SELECTED REFERENCES Baird, V. B. 1942. Wild Violets of North America. Berkeley and Los Angeles. Ballard, H. E. 1992. Systematics of Viola Section Viola in North America North of Mexico. M.S. thesis. Central Michigan University. Ballard, H. E., K. J. Sytsma, and R. R. Kowal. 1998. Shrinking the violets: Phylogenetic relationships of infrageneric groups in Viola (Violaceae) based on internal transcribed spacer DNA sequences. Syst. Bot. 23: 439–458. Beattie, A. J. and N. Lyons. 1975. Seed dispersal in Viola (Violaceae): Adaptations and strategies. Amer. J. Bot. 62: 714–722. Fabijan, D. M., J. G. Packer, and K. E. Denford. 1987. The taxonomy of the Viola nuttallii complex. Canad. J. Bot. 65: 2562–2580. Gil-Ad, N. L. 1997. Systematics of Viola L. subsection Boreali-Americanae. Boissiera 53: 1–130. Gil-Ad, N. L. 1998. The micro-morphologies of seed coats and petal trichomes of the taxa of Viola subsect. Boreali-Americanae (Violaceae) and their utility in discerning orthospecies from hybrids. Brittonia 50: 91–121. Klaber, D. 1976. Violets of the United States. South Brunswick, N.J. Marcussen, T. et al. 2012. Inferring species networks from gene trees in high-polyploid North American and Hawaiian violets (Viola, Violaceae). Syst. Biol. 61: 107–126. McKinney, L. E. 1992. A Taxonomic Revision of the Acaulescent Blue Violets (Viola) of North America. Fort Worth. [Sida Bot. Misc. 7.] Russell, N. H. 1965. Violets (Viola) of the central and eastern United States: An introductory survey. Sida 2: 1–113.
|[Classic Latin name derived from Greek ion, violet]|
Landon E. McKinney "Viola Linn. in Flora of North America @ efloras.org" eFlora. Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA., 2016. Web. Accessed February 2018.