Herbs annual or perennial, shrubs, or subshrubs, sometimes scandent, rarely small trees. Leaves simple, usually alternate, sometimes opposite, with small or leaflike stipules, petiolate, margin entire, serrate, or dissected. Flowers bisexual or unisexual, rarely polygamous, actinomorphic or zygomorphic, solitary or in axillary or terminal, spicate, paniculate, or racemose inflorescences, 2-bracteolate, sometimes cleistogamous. Sepals 5, equal or unequal, imbricate, persistent. Petals 5, imbricate or convolute, unequal, anterior one usually larger than others, saccate, gibbous or spurred at base. Stamens 5; anthers erect, free or connivent or connate, connectives often dilated into membranous appendages; filaments very short or absent, anterior 2 stamens with spurlike nectary at base. Ovary superior, 1-loculed, 3-5-carpelled, syncarpous, with 3-5 parietal placentae each with 1 to many anatropous ovules; style simple; stigmas variously shaped. Fruit a loculicidal capsule, usually with elastic and abaxially carinate valves, rarely baccate. Seeds often carunculate; testa hard, nitid, often with oily bodies, sometimes alate; endosperm copious, fleshy; embryo erect.
Herbs, annual or perennial, [subshrubs, shrubs, lianas, and trees], glabrous or hairy, hairs simple; taprooted or rhizomatous, sometimes stoloniferous. Stems 0–20, prostrate to erect. Leaves cauline or basal, (attached directly to rhizome, some Viola), alternate (and opposite in Hybanthus [and other genera]), simple or compound, stipulate [estipulate], petiolate or sessile; blade unlobed or lobed. Inflorescences 1(–4)[–5]-flowered, axillary from leaf axils or scapose from rhizomes or stolons (or in racemes of umbels), pedunculate; bracteoles usually present on peduncles, usually alternate. Flowers bisexual [unisexual, plants dioecious], perianth and unequal, imbricate in bud [convolute], lowermost petal often larger with gibbous or elongated spur; stamens 5, alternate with petals, surrounding ovary, connivent or syngenesious; filaments 0–1 mm, filaments of 2 anterior stamens often with nectaries protruding into spur, anther dehiscence by longitudinal slits; pistil 1, [2–]3[–5]-carpellate; ovary superior, 1-locular; placentation parietal; ovules [1–2]8–75, anatropous, bitegmic, crassinucellate; style [0–]1, usually enlarged distally, solid or hollow; stigma 1 [3–5], with or without hairs. Fruits capsular [berry, nut], 3-valved, dehiscence loculicidal. Seeds [1–](3–)6–75, hard, embryo not developed at time of dispersal, spheroid or ovoid [strongly flattened], glabrous [hairy], some arillate, some with elaiosome [seeds winged in some woody vines].
Flowers actinomorphic or zygomorphic, from solitary to paniculate
Leaves alternate or rarely opposite, stipulate
Ovary superior, sessile, 1-celled, with usually 3 parietal placentas each with one or more ovules; style usually simple
Stamens hypogynous, 5, alternate with the petals; anthers 2-celled, opening lengthwise, with the connective produced beyond the cells
Petals 5, nearly equal or the lower larger and often clawed, imbricate
Fruit an elastic loculicidal capsule, one- or more-seeded
Seeds with fleshy endosperm and central mostly straight embryo
Seeds generally with ample endosperm, occasionally arillate
Stamens 5, antisepalous, the lower pair (anterior) in zygomorphic flowers each with an appendage which projects into the spur and which secretes nectar; filaments free or united wholly or partly into a ring around the ovary; anthers introrse, usually with a prominent connective appendage, sometimes with thecal appendages also
Ovary sessile, ± ovoid, 1-locular, with (2–)3, 4 or 5 parietal placentas; style solitary, often thickened towards the stigma, which is generally undivided
Fruit a loculicidal capsule, generally splitting into 3 wide-spreading contractile valves, rarely a nut or berry
Annual or perennial herbs, shrubs or small trees
Sepals 5, free or united near the base, usually persistent
Petals 5, free, equal or unequal, the anterior one (lowermost in flower) sometimes spurred, imbricate, generally deciduous
Leaves spirally arranged, rarely opposite or verticillate, simple, entire or toothed, rarely dissected; stipules present, small or foliaceous, the margin often ciliate or laciniate
Flowers actinomorphic or zygomorphic, solitary or in a simple or compound inflorescence, often thyrsoid, terminal or axillary, usually hermaphrodite, sometimes unisexual on separate plants
Sepals 5, free or shortly united, quincuncial or open in bud, usually persistent
Petals 5, free, equal or ± unequal, the anterior one frequently ± spurred, imbricate, usually deciduous, alternating with the sepals
Leaves alternate (rarely opposite or whorled), simple, entire or serrate to dentate (rarely ± dissected), usually with 2 stipules
Flowers actinomorphic or, more often, ± zygomorphic, bisexual (rarely polygamous or dioecious)
Shrubs or perennial or annual herbs (more rarely trees)
Seeds sometimes with a small aril, usually with abundant endosperm
Fruit a loculicidal capsule usually with contractile carinate valves, rarely a berry or nut
Ovary free, sessile, usually ± ovoid, 1-locular, with (2) 3 (4–5) parietal placentas each bearing 1–? ovules; styles completely united, usually thickened above, often ± S-shaped in zygomorphic flowers, stigma usually undivided
Stamens 5, antisepalous, similar or ± dissimilar, the anterior pair in zygomorphic flowers with appendages which project into the spur, filaments free ± united, often forming a cylinder round the ovary; anthers usually introrse, free ± united, usually with a prolongation of the connective
SELECTED REFERENCES Ballard, H. E., J. de Paula-Souza, and G. A. Wahlert. 2014. Violaceae. In: The Families and Genera of Vascular Plants. Vol. 11, pp. 303–322. Berlin, Heidelberg. Brainerd, E. 1921. Violets of North America. Bull. Vermont Agric. Exp. Sta. 224. Brizicky, G. K. 1961b. The genera of Violaceae in the southeastern United States. J. Arnold Arbor. 42: 321–333. Feng, M. 2005. Floral Morphogenesis and Molecular Systematics of the Family Violaceae. Ph.D. dissertation. Ohio University. Feng, M. and H. E. Ballard. 2005. Molecular systematic, floral developmental and anatomical revelations on generic relationships and evolutionary patterns in the Violaceae. In: International Botanical Congress. 2005. XVII International Botanical Congress, Vienna, Austria, Europe, Austria Center Vienna, 17–23 July 2005. Abstracts. P. 169. Gershoy, A. 1928. Studies in North American violets. I. General considerations. Bull. Vermont Agric. Exp. Sta. 279. Hodges, S. A. et al. 1995. Generic relationships in the Violaceae: Data from morphology, anatomy, chromosome numbers and rbcL sequences. [Abstract.] Amer. J. Bot. 82(6, suppl.): 136. McKinney, L. E. and N. H. Russell. 2002. Violaceae of the southeastern United States. Castanea 4: 369–379. Tokuoka, T. 2008. Molecular phylogenetic analysis of Violaceae (Malpighiales) based on plastid and nuclear DNA sequences. J. Pl. Res. 121: 253–260. Wahlert, G. A. et al. 2014. Phylogeny of the Violaceae (Malpighiales) inferred from plastid DNA sequences: Implications for generic diversity and intrafamilial classification. Syst. Bot. 39: 239–252.
Landon E. McKinney "Violaceae Batsch in Flora of North America @ efloras.org" eFlora. Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA., 2016. Web. Accessed February 2018.