Violaceae is afamily offlowering plants established in 1802, consisting of about 1000 species in about 25 genera. It takes its name from thegenusViola, the violets andpansies.
Older classifications such as theCronquist system placed the Violaceae in anorder named after it, theViolales or theParietales. However,molecular phylogeny studies place the family in theMalpighiales as reflected in theAngiosperm Phylogeny Group (APG) classification, with 41 other families, where it is situated in the parietalclade of 11 families. Most of the species are found in three large genera,Viola,Rinorea andHybanthus. The other genera are largelymonotypic or oligotypic. The genera are grouped into four clades within the family. The species are largely tropical or subtropical butViola has a number of species intemperate regions. Many genera have a very restricted distribution.
Though the best-known genus,Viola, isherbaceous, most species areshrubs,lianas or smalltrees. The simpleleaves are alternate or opposite, often with leafy stipules or the stipules are reduced in size. Some species have palmate or deeply dissected leaves. Many species areacaulescent. The flower are solitary inpanicles. Some species havecleistogamous flowers produced after or before the production of typical flowers with petals. Flowers are bisexual or unisexual (e.g.Melicytus),actinomorphic but typicallyzygomorphic with acalyx of five sepals that are persistent after flowering. Corollae have five mostly unequal petals, and the anterior petal is larger and often spurred. Plants have five stamens with the abaxial stamen often spurred at the base. The gynoecium is a compound pistil of three united carpels with onelocule. Styles are simple, with the ovary superior and containing many ovules. The fruits are capsules split by way of three seams. Seeds haveendosperm.[3][4][5]
ThatViola, previously included byJussieu (1789) underCisti,[6] should have its own family was first proposed byVentenat in 1799,[7] and in 1803 placed theViola species in a new genus,Ionidium which he described as "Famille des violettes."[8][4] However, in the meantimeBatsch established the Violaceae, as a suprageneric rank under the name of Violariae (1802), and as the first formal description, bears his name as thebotanical authority.[9] Batsch included eightgenera in thisfamily.[10] Although Violariae continued to be used by some authors, such asDon (1831)[11] andBentham and Hooker (1862) (as Violarieae),[12] most authors, such asEngler (1895),[13] adopted the alternative name Violaceae, proposed byde Lamarck andde Candolle in 1805,[14] and later byGingins (1823)[15] andSaint-Hilaire (1824).[16] With the establishment of higher suprafamiliar orders, which he called "Alliances",Lindley (1853) placed his Violaceae within theViolales.[17]
The Violaceae are a medium-sized family with about 22–28genera, and about 1,000–1,100species. Most of the genera aremonotypic oroligotypic, but the three generaViola (about 600 species),Rinorea (about 250 species), andHybanthus include 98% of the species with about half the species inViola, and more than three-quarters of the remainder in the other two genera.[3][25][22][4]
Many attempts have been made at an intrafamilial classification, but these have largely been artificial, based on floral characteristics. Subdivisions were recognized almost immediately. Early classifications identified two major divisions, that were followed by most taxonomists;[15][17]
These also hadbiogeographical correlation, with the latter being almost exclusively South American and African, and the former being distributed in Europe in addition to the Americas.[17] In contrast, Bentham and Hooker (and some others) divided Alsodeieae, giving three tribes;
Violeae. Strictly zygomorphic
Paypayroleae. Actinomorphic with some zygomorphic features
Alsodeieae. Strictly actinomorphic
Melchior utilized a more complex classification with two subfamilies, tribes and subtribes to recognize the place ofLeonia within the Violaceae;.[4]
The historical subdivisions shown here are those of the system of Hekking (1988), based largely on floral symmetry, petal aestivation and petal morphology. In this system, most genera occur in the Rinoreae and Violeae tribes.[26] Threesubfamilies have been recognized: the Violoideae, Leonioideae, and Fusispermoideae.[27][3]
Molecular phylogenetic studies have revealed that many of these divisions were notmonophyletic, partly due tohomoplasy. These studies demonstrate four major clades within the family.[3]
In Clade 1,Schweiggeria andNoisettia are monotypic and form a sister group toViola. In addition to the major clades, there were a number of unplaced segregates.[3]
The Violaceae have an overallcosmopolitan distribution,[3] but are essentially tropical and subtropical, with the exception of the numerous Northern Hemisphere temperate species ofViola, the largest genus, which is also occurs at higher altitudes in its tropical and subtropical regions, where the shrub, tree and lianescent species are concentrated. In those regions, most representative genera are the mainly woodyRinorea andHybanthus.[26] WhileViola,Hybanthus, andRinorea are widely distributed in both hemispheres, the remaining genera are relatively restricted in their distribution. Some are restricted to a single continent while others have a limited area involving just a singlearchipelago.[4] About 70 species are found in Brazil.[26][28]
