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Viola subsect. Pedatae (Pollard ex W. Becker) Brizicky ex Marcussen & H. E. Ballard, stat. nov.
≡ Basionym: Viola [unranked] Pedatae Pollard ex W. Becker in Nat. Pflanzenfam., ed. 2 [Engler & Prantl], 21: 369. 1925
≡ Viola “class” Pedatae Pollard in Bot. Gaz. 26: 237. 1898, nomen inval. (Shenzen Code Art. 37.6)
≡ Viola subsect. Pedatae “(Pollard) Brizicky” in J. Arnold Arb. 42: 327. 1961, nom. inval. (Shenzhen Code Art. 41.5)
≡ Viola sect. Pedatae (Pollard ex W. Becker) Espeut in Botanica Pacifica 9(1): 35. 2020—Type (Shenzhen Code Art. 10.8): Viola pedata L.
≡Oionychion Nieuwl. & Kaczm. in Amer. Midl. Naturalist 3: 210. 1914.
—Type: Viola pedata L.
Description.—Perennial herbs. Axes not morphologically differentiated; stem a rhizome terminating in an apical rosette. Rhizome thick, vertical and barrel-like. Stipules narrow, long-adnate to petiole. Laminas deeply pedately divided (rare variations with triternate or merely apically incised laminas). Calycine appendages prominent, truncate or dentate. Petals violet, beardless. Style clavate, apex narrowly rounded from above, with dorsolateral margin as a narrowly rounded rim continuing to the ventral surface, the stigma hidden in the narrow triangular cavity created by the rim. Cleistogamous flowers not produced. Secondary base chromosome number x’ = 27.
Diagnostic characters.—Rosulate acaulescent AND stipules long-adnate AND laminas deeply pedately divided (rarely otherwise) AND petals violet AND all petals beardless AND style with narrowly rounded dorsolateral rim and hidden stigma AND cleistogamous flowers not produced. Allodecaploid. n = 27.
Ploidy and accepted chromosome counts.—10x; 2n = 54.
Age.—Crown node not applicable (monotypic subsection), stem node age 5.0–6.0 Ma [45].
Included species.—1.
Distribution.—Eastern North America.
Discussion.—A monotypic subsection for Viola pedata, a widely distributed eastern North American species of dry oak woodlands, oak savannas and dry prairies. The subsection (and species) are unusual in having a short vertical barrel-like rhizome pulled below the soil surface by contractile roots, long-adnate stipules, a clavate or narrowly ellipsoid style lacking a noticeable to prominent thickened dorsolateral rim (this simply a thin non-spreading margin), and absence of cleistogamy. The type variety produces deeply pedately divided laminas with linear segments; populations with narrowly flabellate laminas in the Sandhills region of the southeastern U.S. and populations with triternately divided laminas in the east-central Piedmont, are treated as varieties. This species is unusual also in maintaining a presumably balanced polymorphism in corolla colour pattern, with individuals with dark violet-black upper petals increasingly common further south in the range, and individuals with all petals light violet increasingly common to the north. Finally, V. pedata is the only member of the genus reported to be self-incompatible [280]. Phylogenetic studies involving all North American lineages have shown that, like V. clauseniana, V. pedata does belong to the Nosphinium lineage but has ambiguous relationships among the other species. It has retained the initial allodecaploid constitution of the ancestor of the Nosphinium lineage [45] but has obviously diverged considerably from the other subsections.
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