Viola nephrophylla
Viola biflora
kidney-leaf violet, Leconte violet, northern bog violet, violette néphrophylle
arctic yellow violet, European field pansy, northern violet, queen Charlotte twinflower violet, twinflower violet
1–3+, ascending or erect, leafy proximally and distally, glabrous, on caudex from fleshy rhizome.
basal, 4–7, ascending to erect;
stipules lanceolate, margins entire or fimbriate, apex acute;
petiole 2–25 cm, usually glabrous;
blade usually grayish green or purplish green abaxially, unlobed, ovate, reniform, or broadly reniform to orbiculate, 1–7 × 1–7 cm, somewhat fleshy, base broadly cordate or reniform to ± truncate, margins crenate to serrate, ciliate or eciliate, apex acute to obtuse or rounded, surfaces usually glabrous, rarely sparsely pubescent.
basal and cauline;
basal: 2–3(–4);
stipules ovate-lanceolate, ovate, or oblong, margins entire, apex ± acute;
petiole 1.5–15 cm, glabrous;
blade broadly reniform to orbiculate, 0.5–4.6 × 0.9–6.4 cm, base cordate, margins crenate to crenate-serrate, ciliate, apex obtuse, rounded, or truncate, rarely with terminal point, abaxial surface sparsely puberulent on veins, adaxial surface glabrate to ± densely puberulent;
cauline similar to basal except: stipules lanceolate, ovate, or oblong, margins entire to erose, apex acute to obtuse;
petiole 0.3–7(–10) cm;
blade sometimes ovate, 0.8–3.7 × 1–4.8 cm.
3–25 cm, usually glabrous.
2–9 cm, usually glabrous.
sepals ovate, margins usually eciliate, auricles 1–2 mm;
petals deep bluish violet on both surfaces, lower 3 white basally and darker violet-veined, lateral 2 bearded, upper 2 sometimes sparsely bearded, lowest densely bearded or beardless, 10–28 mm, spur same color as petals, gibbous, 2–3 mm;
style head beardless; cleistogamous flowers on erect to ascending peduncles.
sepals with or without purple stripe on both sides of midvein, narrowly lanceolate to oblong, margins ciliate or eciliate, auricles 0.5–1 mm;
petals deep lemon-yellow on both surfaces, lower 3 and often upper 2 brownish purple-veined, lateral 2 beardless, lowest 6–15 mm, spur yellow to yellowish green, gibbous, 2–2.5 mm;
style head beardless; cleistogamous flowers axillary.
ovoid, 5–10 mm, glabrous.
oblong-ovoid, 3–6 mm, glabrous or sparsely pubescent.
beige to brown or dark brown, 1.5–2.5 mm.
purple, sometimes streaked with light and dark brown, 1.5–2.5 mm.
= 54.
Viola nephrophylla
Viola biflora
Viola nephrophylla has the widest distribution in North America of any of the acaulescent blue violets.
There is some question whether the species we now know as Viola nephrophylla fits with the protologue and type specimen(s). McKinney examined the type designated by Greene; it appears that what most botanists have called V. nephrophylla may be an undescribed taxon. N. L. Gil-Ad (1997) believed Greene’s type contained plants that were genetically impure based on seed coat micromorphology and suggested the specimens might be a mixture of both orthospecies and introgressants.
Viola mccabeiana was described by M. S. Baker in 1940 from collections made in British Columbia. Later, Baker (1949b) discussed the reasons why the name V. mccabeiana needed to be abandoned. C. L. Hitchcock et al. (1955–1969, vol. 3) treated V. mccabeiana as synonymous with V. nephrophylla var. cognata. While Viola mccabeiana is recognized in Canada (L. Brouillet et al., http://data.canadensys.net/vascan/), we believe it is best included within V. nephrophylla.
Viola nephrophylla reportedly hybridizes with V. cucullata (= V. ×insessa House), V. sororia var. sororia (= V. ×napae House), and V. affinis (= V. ×subaffinis House).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 5 (2 in the flora).
Viola biflora may be the most widely distributed species of the genus in the Northern Hemisphere. Although occurring most often in mountainous areas at high elevations, it is known from Alaska near the coast at elevations of ca. 45 m (PNW Herbaria Portal 2010) and has been reported from lowland meadows in Kamchatka (V. B. Baird 1942), and is occasionally found near sea level in exposed rocky habitats on the west coast of the Queen Charlotte Islands (R. A. Calder and R. L. Taylor 1968).
Sometimes described as high latitude, circumpolar, Viola biflora also occurs in mid latitudes north of the equator. It is not truly circumpolar; it does not occur in eastern Canada or in Greenland. The deeply cleft style head sets V. biflora apart from all other species in North America. V. B. Baird (1942) suggested that the occasional presence of two cleistogamous flowers in the axil of the same leaf may account for the name “biflora.”
H. N. Ridley (1930) said that in Europe, deer (Cervus dama Linnaeus and Rangifer tarandus Linnaeus) may play a role in the dispersal of Viola biflora; seeds have been recovered from their droppings.
Nonflowering Viola biflora can be confused with V. renifolia where their ranges overlap in Yukon, Alaska, and Colorado.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Lowest petal 6–10 mm; seeds 1.5–2 mm; sepals usually without purple stripe; Yukon, Alaska, Colorado. | var. biflora |
1. Lowest petal 11–15 mm; seeds 2.5 mm; sepals usually with purple stripe; Queen Charlotte Islands, Vancouver Island, British Columbia. | var. carlottae |
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