[2.18.2] Viola subsect. Viola

Viola subsect. Viola

=Viola sect. Odoratae Boiss. in Diagn. Pl. Orient. 8: 51. 1849, nom. inval. (Szhenzhen Code Art. 22.2; Viola odorata L.)

=Viola sect. Hypocarpea Godron, Fl. Lorraine, ed. 2, 1: 86. 1857 ≡ Viola subsect. Hypocarpea (Godron) P. Y. Fu, Fl. Pl. Herb. Chin. Bor.-Or. 6: 82. 1977, nom. inval. (Szhenzhen Code Art. 22.2; Viola odorata L.)

=Viola [unranked] (”Gruppe”) Uncinatae Kupffer in Oesterr. Bot. Z. 53: 328. 1903, nom inval. (Szhenzhen Code Art. 22.2; Viola odorata L.) ≡ Viola sect. Uncinatae (Kupffer) Kupffer in Kusnezow et al., Fl. Caucas. Crit. 3(9): 174. 1909, nom. inval. (Szhenzhen Code Art. 22.2)

=Viola [unranked] a) Curvato-pedunculatae W. Becker in Beih. Bot. Centralbl., Abt. 2, 26: 1. 1910, nom. inval. (Szhenzhen Code Art. 22.2; Viola odorata L.)

=Viola subg. Euion Nieuwl. & Kaczm. in Amer. Midl. Naturalist 3: 211. 1914, nom. inval. (Szhenzhen Code Art. 22.2; Viola odorata L.)

=Viola [unranked] α Lignosae W. Becker in Beih. Bot. Centralbl., Abt. 2, 26: 1. 1910 ≡ Viola [unranked] (“Gruppe”) D. Lignosae W. Becker in Nat. Pflanzenfam. ed. 2 [Engler & Prantl], 21: 367. 1925.—Lectotype (designated here): Viola chelmea Boiss.

=Viola [unranked] (“Gruppe”) Serpentes W. Becker in Beih. Bot. Centralbl., Abt. 2, 40: 102. 1924—Viola subsect. Serpentes (W. Becker) W. Becker in Acta Horti Gothoburg. 2: 287. 1926—Viola ser. Serpentes (W. Becker) Steenis in Bull. Jard. Bot. Buitenzorg, ser. 3, 13 (1933–1936): 259. 1934—Viola sect. Serpentes Ching J. Wang, Fl. Reipubl. Popularis Sin. 51: 88. 1991.—Type (Shenzhen Code Art. 10.8): Viola serpens Wall. ex Ging. (=V. pilosa Blume)

Description.—Rhizome with apical rosette of leaves. Lateral stolons present or absent. Stipules free, not foliaceous. Style beardless. Capsule globose, non-explosive. Seeds with large elaiosome.

Diagnostic characters.—Capsules globose, usually hairy, decumbent at maturity, non-dehiscent. Seeds with a large elaiosome covering 1/2–3/4 of the raphe.

Ploidy and accepted chromosome counts.—4x, 8x; 2n = 20, 40.

Age.—Crown node age c. 5 Ma [92]; stem node 11.8 (10.1–12.4) Ma [28].

Included species.—25.

Viola alba Besser, V. ambigua Waldst. & Kit., V. barhalensis G. Knoche & Marcussen, V. bocquetiana Yıld., V. canescens Wall., V. chelmea Boiss., V. collina Besser, Viola evoluta C. Z. Huang, X. Zhong and Xiao C. Li sp. nov., V. hirta L., V. hondoensis W. Becker & H. Boissieu, V. indica W. Becker, V. isaurica Contandr. & Quézel, V. jangiensis W. Becker, V. jaubertiana Marès & Vigin., V. kizildaghensis Dinç & Yıld., V. libanotica Boiss., V. odorata L., V. pilosa Blume, V. pyrenaica Ramond ex DC., V. sandrasea Melch., V. sintenisii W. Becker, V. suavis M. Bieb., V. thomasiana Songeon & E. P. Perrier, V. vilaensis Hayek, V. yildirimlii Dinç & Bagci

Distribution.—Eurasia; diversity centre in southern Europe. Viola odorata is naturalised throughout the temperate zone.

Discussion.—The principal apomorphy of subsect. Viola is the globose and non-explosive capsules borne on decumbent peduncles, containing large seeds with a conspicuous elaiosome, an adaptation to obligate myrmecochory. Subsection Viola as circumscribed here comprises three of Becker’s [1] greges. These include grex Uncinatae W. Becker (V. odorata, etc.) with both stolonose and estolonose temperate taxa, grex Lignosae W. Becker (V. chelmea, etc.) with estolonose taxa from the northeastern Mediterranean region, and parts of grex Serpentes W. Becker (V. pilosa, etc.) with stolonose taxa from southern Asia. The presence or absence of stolons has been used to classify species within the subsection but does not delimitate monophyletic groups [116]. At least in European species, the transitions from the stolonose condition (ser. Flagellatae Kittel) to the estolonose condition (ser. Eflagellatae Kittel) seems to have occurred several times and by different genetic mechanisms, and the two morphological groups are also linked by allopolyploidy, i.e., V. suavis (8x) [116]. Grex Serpentes has been demonstrated to be an artificial aggregate of species [229], most of them belonging in sect. Viola subsect. Viola or in various sect. Plagiostigma subsections.

A few species are grown as ornamentals, primarily for their fragrant flowers, i.e., V. odorata and filled forms of V. alba subsp. dehnhardtii (Ten.) W. Becker referred to as ‘Parma’ violets or ‘Violette de Toulouse’ [7,20]. The former (Figure 1) has been cultivated for the production of essential oil for the perfume industry [16,17].