Viola nephrophylla Greene. Section: Nosphinium. Subsection: Borealiamericanae. Northern Bog Violet. Phen: May-Jun. Hab: Strongly calciphilic, seasonally or perennially saturated open sites such as bedrock pavement, rocky shores, fens, marl bogs and wet prairies, occasionally in disturbed sites especially around crushed limestone. Dist: NL (Newfoundland) and YT south to PA, WV, VA (where perhaps only introduced), IN, IL, LA, TX, CA, and Mexico (COA, NLE, SON).

ID notes:This species has undivided broadly ovate or orbiculate to reniform blades with broadly obtuse (rarely broadly acute) to rounded apex and crenate margins that do not appear to broaden much in fruit, the foliage glabrous except for small scattered subappressed hairs on the upper surface of the blades. As such it could be confused with a diversity of other Borealiamericanae taxa with somewhat similar foliage at any time during the growing season, including V. communis, V. latiuscula, V. pratincola, V. retusa, V. sororia (glabrous variant), and V. sororia (hirsutuloides variant). In chasmogamous flower it differs from V. communis, V. sororia (glabrous variant), and V. sororia (hirsutuloides variant) in its typically densely bearded spurred petal, and additionally from V. communis in its obtuse to rounded sepals and short rounded auricles; and from V. latiuscula, V. pratincola, and V. retusa by its rounded sepals, and further from the latter two in its short rounded auricles. In cleistogamous fruit it can be separated from V. communis, V. pratincola, and V. retusa by its short declined or ascending peduncle and brown usually unspotted seeds; and from V. sororia (glabrous variant) and V. sororia (hirsutuloides variant) by its unspotted capsule and brown unspotted seeds.

Origin/Endemic status: Native

Taxonomy Comments: Greene described several species based on minute “distinctions”, but nearly all of them represent normal within-population variation in this transcontinental species. The status of Viola arizonica Greene and a few other western taxa, however, requires further study.

Synonymy: = C, F, FNA6, G, GrPl, Il, K1, K3, Mex, NE, Tx, WV, Ballard () (in prep), Ballard, Kartesz, & Nishino (2023), Haines (2001); < Viola nephrophylla Greene – K4

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FACW (taxonomic split from wetland indicator species)
• Eastern Mountains and Piedmont: FACW (taxonomic split from wetland indicator species)
• Great Plains: FACW (taxonomic split from wetland indicator species)
• Midwest: FACW (taxonomic split from wetland indicator species)
• Northcentral & Northeast: FACW (taxonomic split from wetland indicator species)

Heliophily: 6