[2.9] Viola sect. Melanium

Viola sect. Melanium Ging. in Mém. Soc. Phys. Genève 2(1): 28. 1823

 ≡ Viola subg. Melanium (Ging.) Peterm., Deutschl. Fl.: 65. 1846; (Ging.) Kupffer in Kusnezow et al., Fl. Caucas. Crit. 3(9): 221. 1909 (isonym)

Type: Viola tricolor L.

≡Mnemion Spach, Hist. Nat. Vég. [Spach] 5: 510. 1836—Lectotype (Nieuwland & Kaczmarek 1914 [249], page 210): Viola tricolor L.

≡Viola sect. Pogonostylos Godron, Fl. Lorraine, ed. 2, 1: 90. 1857, nom. illeg. superfl. (Szhenzhen Code Art. 52.1; Viola tricolor L.)

≡Viola sect. Novercula Kupffer in Kusnezow et al., Fl. Caucas. Crit. 3(9): 225. 1909, nom illeg. superfl. (Szhenzhen Code Art. 52.1; Viola tricolor L.)

=Jacea Opiz in Bercht. & Opiz, Oekon.-Techn. Fl. Böhm. [Berchtold & al.] 2(2): 8. 1839, nom. illeg., non Mill., Gard. Dict. Abr., ed. 4: [not paginated]. 1754 (=Centaurea)

Description.—Annual to perennial herbs. Taproot preserved, in perennials often deeply buried and thickened. Axes not morphologically differentiated. All stems more or less aerial; in perennials proximal portion rhizome-like. Stipules usually foliaceous, pinnately or palmately lobed with leaflike segments. Lamina entire, crenulate or crenate, petiolate. Corolla small or large (bottom petal 2–34 mm), often varicoloured and/or variegated, nearly always with a yellow throat. Spur short or long and slender (0.9–16 mm). Calycine appendages short or long (0.5–5.3 mm). Style capitate, bearded. Cleistogamous flowers usually not produced; if produced, then cleistogamy seasonal (V. rafinesquei). Allotetraploid (CHAM + MELVIO). ITS sequence of MELVIO type. Aneuploid.

Diagnostic characters.—All stems more or less aerial AND stipules usually foliaceous AND corolla small to very large, nearly always with a yellow throat.

Ploidy and accepted chromosome counts.—4x, 8x, 12x, 16x, 20x, >20x; 2n = 4, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 34, 36, 40, 48, 52, c.64, c.96, 120, c. 128.

Age.—Crown node age 12.5 (11.8–12.8) Ma [28].

Included species.—112.

Distribution.—Western Eurasia; one species in eastern North America (Figure 1). Mainly in mountainous areas, with a centre of diversity in the mountains of the Balkans, Apennine Peninsula and Sicily, seven species in northwestern Africa (three of them endemic) and one species in eastern North America (Viola rafinesquei). A few species are widespread in the lowlands, nearly all annuals or biennials (e.g., V. arvensis, V. tricolor, and V. rafinesquei).

Discussion see Marcussen T. et al.  2022 pag 54-57