Viola affinis Leconte. Section: Nosphinium. Subsection: Borealiamericanae. Phen: Chasmogamous flower Apr–May; chasmogamous fruit Jun; cleistogamous fruit Jun-Sep. Hab: Damp to saturated (less typically periodically inundated), often sandy soils bordering vernal pools, streams and rivers in mesic to wet forests, and on terraces in floodplains and swamp borders. Dist: ME to se. MN, south to GA and AR.
ID notes: This species has the distinction of being the only Borealiamericanae violet to have frequently hirtellous cleistogamous capsules; the only other acaulescent eastern North American violet with hirtellous capsules is the often cultivated and escaped European V. odorata. In chasmogamous flower, with its narrowly ovate leaf blades longer than broad, this species can be distinguished from V. cucullata by its short rounded auricles, lack of a conspicuously contrasting dark purple eyespot around the throat, long narrowly linear to weakly clavate hairs in the lateral petal beards, and densely bearded spurred petal; from V. langloisii by its strongly ascending to erect leaves, short rounded auricles, and densely bearded spurred petal; from V. missouriensis by leaves with the upper surface bearing scattered subappressed hairs, lanceolate to linear-lanceolate acuminate eciliate sepals, and densely bearded spurred petal; and from V. pratincola and V. retusa by its leaves with upper surface bearing scattered subappressed hairs, and short rounded auricles. In cleistogamous fruit, once its leaves have broadened substantially, it can be separated from V. communis, V. cucullata, V. langloisii, V. pratincola, and V. retusa by the heavily spotted or blotched (and occasionally hirtellous) cleistogamous capsule on a prostrate peduncle; from V. sororia ("var. 1" and "var. 2" variants) by its narrow sharply acute sepals and yellow- to orange-brown seeds. It is distinct from V. missouriensis in its leaves with upper surfaces bearing scattered subappressed hairs, and lanceolate to linear-lanceolate acuminate eciliate sepals.
Origin/Endemic status: Native
Synonymy: = F, FNA6, G, GW2, Il, Mi, NE, Pa, RAB, S, Va, W, WV, Ballard () (in prep), Ballard, Kartesz, & Nishino (2023), Gil-ad (1998), Haines (2001); < Viola affinis Leconte – K3; < Viola missouriensis Greene – Tn; > Viola papilionacea Pursh, as to type; < Viola sororia Willd. – C; < Viola sororia Willd. var. missouriensis (Greene) L.E.McKinney – McKinney & Russell (2002)