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Section Photogallery
Included species.—3.
Included species.—69.
Included species.—7.
Included species.—1.
Included species.—3.
Included species.—11.
Included species.—1.
Included species.—18.
Included species.—112.
Included species.—98.
Included species.—1.
Included species.—3.
Included species.—9.
Included species.—1.
Included species.—1.
Included species.—1.
Included species.—62.
Included species.—38.
Included species.—1.
Included species.—3.
Included species.—10.
Included species.—9.
Included species.—1.
Included species.—142.
Included species.—10.
Included species.—8.
Included species.—2.
Included species.—23.
Included species.—2.
Included species.—62.
Included species.—41.
Included species.—3.
Included species.—7.
Included species.—3.
Included species.—1.
Included species.—75.
Included species.—53.
Included species.—24.
sect. Xanthidium
Included species.—2.
sect. Xylinosium
Included species.—3.
=Viola sect. Sparsifoliae Reiche in Nat. Pflanzenfam., ed. 1 [Engler & Prantl], 3(6): 334. 1895, nom. inval. L.)
Type specie: Viola odorata L.
Description.—Annual or perennial herbs, subshrubs or very occasionally treelets. Axes morphologically differentiated or not. Leaves scattered on stems or in rosettes, very occasionally imbricated with distichous phyllotaxy (sect. Tridens). Stipules free or partially adnate, sometimes large and foliaceous. Lamina usually petiolate; young laminas with involute margins (rarely folded in narrow leaves). Peduncles often longer than mature leaves. Bottom petal usually entire or shallowly emarginate, very rarely cleft. Spur absent to very long (34 mm). Nectariferous appendage of the two bottom stamens of various shape, rarely filiform. Style filiform, clavate, or capitate, not crested (but lateral lobes present in sect. Sclerosium) but top of style apex often flattened or with more or less raised edges, bearded or beardless. Cleistogamous flowers often produced.
Diagnostic characters.—Young laminas with involute margins OR peduncles longer than mature leaves OR style not crested OR cleistogamous flowers present.
Ploidy and accepted chromosome counts.—2x, 4x, 6x, 8x, 10x, 12x, 14x, 16x, 18x, 20x, >20x. 2n = 4, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 34, 36, 40, 44, c. 44, 46, 48, 50, 52, 54, 58, 60, c. 64, 72, 76, 80, c. 80, 82, c. 96, 102, c. 120, 128.
Age.—Crown node age 29.0 (28.3–29.4) Ma; stem node age 30.9 (29.8–31.3) Ma [1].
Included species.—525.
Distribution.—All continents except Antarctica. Diversity centres in e Asia, w Eurasia and N America.
Discussion.—Within subg. Viola we recognise 20 sections which can be grouped in three well-separated biogeographic clusters and allopolyploid tangles. The first cluster occurs in South and Central America and Australasia and comprises 43 species in 7 sections (sects. Chilenium, Erpetion, Leptidium, Nematocaulon, Rubellium, Tridens, and Xanthidium). The second cluster occurs primarily in the northern hemisphere and comprises 470 species in 12 sections (sects. Abyssinium, Chamaemelanium, Danxiaviola, Delphiniopsis, Himalayum, Melanium, Nosphinium, Plagiostigma, Sclerosium, Spathulidium, Viola, and Xylinosium). The third cluster occurs in South Africa with a single allopolyploid section and species (sect. Melvio; V. decumbens). The last two clusters are phylogenetically nested within the first one. Sections Chamaemelanium and Rubellium (2n = 12) are the only diploid lineages within subg. Viola (no data for sect. Xanthidium).
sect. Xanthidium
sect. Xylinosium
References
Marcussen, T.; Heier, L.; Brysting, A.K.; Oxelman, B.; Jakobsen, K.S. From gene trees to a dated allopolyploid network: Insights from the angiosperm genus Viola (Violaceae). Syst. Biol. 2015, 64, 84–101.