Diagnostic Characteristics
According to Ballard (1988), V. novae-angliae can be distinguished from other violets with which it shares its range, by its stemless, non-stoloniferous habit, blue flowers with bearded lateral and spurred petals, lance-ovate, rounded sepals, and villous, long-triangular, unlobed leaves.
Habitat
There was a belief in the past that V. novae-angliae grew best in rock crevices along the shores of the lakes or beside cold, rapidly flowing streams (Smith 1988; McGuire 1985; Alverson and Iltis 1979; Russell 1965, 1957-1958), indicating a requirement of cool clear water (Cook, et al. 1987) or humid conditions for growth. It is probable that this conception was entirely based on Russell's (1957-1958) monograph on the violets of Minnesota.
Recent work by Ballard (1989a) in the Great Lakes region suggested a different scenario. Ballard (1989a) stated:
"The natural, undisturbed habitat for the taxon was clearly acidic, xeric or xero-mesic rock or sand substrates, under partially or totally closed-canopy dry northern forest of mixed hardwoods and conifers. Soil moisture varied slightly in natural situations but was virtually always low over most of the growing season. Plant density was low in natural settings, with plants scattered singly throughout an area of uniform habitat. Plant density and frequency was found to be high only in sites where extensive natural or artificial disturbance opened the canopy, and more so where lichens and other native ground-layer species were largely scraped away or mowed. The taxon reached its greatest abundance in such sites as fallow meadows and roadside clearings adjacent to granitic outcrops. Interestingly, the taxon was always found to be virtually absent (or not vigorous or in high frequency where found) in otherwise similar situations where timber management had favored high percentages of acidic, long-leaved pines (Pinus resinosa in particular). The taxon's presence in a number of unmanaged areas adjacent to such managed areas, where it was conspicuously absent, suggests that V. novae-angliae does not grow well either in strongly acidic soils or soils heavily covered with pine needle duff.
Published accounts of its habitat notwithstanding, the taxon was found near bodies of water not due to strong moisture preference, but evidently due to greater exposure of xeric rock and sand substrates, less shading, and less competition from native ground-layer species. The apparently acidic nature of the substrate occupied by the taxon is dramatically different in pH than the strongly calcareous rock substrates it has been found on in Maine. Presumably, pH is not the limiting factor; but shade levels, substrate moisture, and competition from native ground-layer species are."
Ballard (1988) stated that the species is only found where forest openings have been maintained, either naturally or artificially. Areas with seemingly appropriate habitat, but managed for pine regeneration, were found to never possess the plant. Apparently, V. novae-angliae is not able to withstand the pine needle duff accumulation brought on by the forestry practice favoring monocultural pine regeneration (Ballard 1988).
In conditions where the optimal natural conditions are exaggerated (as in a road cut enlarging a natural clearing), the New England violet is able to invade the areas at densities, numbers of individuals and fecundity rates far exceeding those found in all natural conditions (Ballard 1989a, 1988). Apparently, this is a rather common phenomenon throughout the genus Viola. Ballard (1988) additionally stated that the largest populations were located within a shrub-free, upland, power-line clearing across the top of large bedrock domes, and in gravelly, grassy ditches adjacent to bedrock knobs cleaved by county roads or campground entrance trails.
V. novae-angliae is a dry-land plant which apparently prefers dry to mesic-dry, circumneutral or slightly acidic substrates, being partial to very thin soil over bedrock (Ballard 1988), particularly on top of or around the bases of granite knobs (Ballard 1989a). Such habitats are typical of Upper Midwestern sites. In Wisconsin, the species is found occurring along rivers, in cold, boggy soils, dry sandy soils in upland woods and on gravelly or sandy stream banks (WI DNR 1981). For a detailed list of historical and new sites found by Ballard (which includes most of the sites outside of Maine), see Ballard (1989a).
In New York State (Mitchell and Sheviak 1981) and other New England states (Cook 1982), the plant is apparently restricted to sandy and gravelly pockets among cobbles along water courses. Since the species is apparently restricted to open areas, which are rare along water courses, available habitat is scarce.
Maine populations are restricted to calcareous slate ledges of the lower Penobscot, St. John and Allagash Rivers. At one site, the plants occur well-below the spring high-water mark, although they are above water during the entire growing season (Gawler 1982). Seasonal flooding via intense summer rains may periodically immerse plants, however.
Ecology
Very little is known with respect to the biology or ecology of V. novae-angliae. This taxon has never been studied to any large extent and even its distribution and habitat preferences were largely unknown prior to 1988.
Ballard (pers. comm., 1989a) stated that he has reduced the status of V. novae-angliae to a subspecific rank under Viola sororia Willd. The taxon should be listed as V. sororia ssp. novae-angliae (House) H. E. Ballard, Jr. (Ballard pers. comm.).