Viola rostrata
Viola biflora
long-spur violet, violette rostrée
arctic yellow violet, European field pansy, northern violet, queen Charlotte twinflower violet, twinflower violet
1–7, ascending to erect (often declining during anthesis), glabrous, on caudex from fleshy rhizome.
1–3+, ascending or erect, leafy proximally and distally, glabrous, on caudex from fleshy rhizome.
basal and cauline;
basal: 1–5;
stipules lanceolate, margins laciniate, apex acute;
petiole 1–9.6 cm, glabrous;
blade sometimes purple-spotted abaxially and/or adaxially, reniform to ovate, 1–4.5 × 1–4 cm, base broadly cordate to cordate, margins crenate to serrate, mostly eciliate, apex obtuse to acute, surfaces usually pubescent, mostly adaxially toward base, sometimes glabrous;
cauline similar to basal except: petiole 0.4–4 cm;
distal cauline blades ovate to deltate, 1–4.5 × 1–4 cm, base cordate, apex acuminate to acute.
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.
5–9 cm, usually glabrous.
2–9 cm, usually glabrous.
sepals lanceolate, margins eciliate, auricles 1–2 mm;
petals pale lavender-violet on both surfaces, all white basally, lower 3 purple-black-veined, all beardless, lowest 8–20 mm, spur white, purple, or lavender-tinged, elongated, 10–20 mm;
style head beardless; cleistogamous flowers axillary.
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.
ellipsoid, 4–6 mm, glabrous.
oblong-ovoid, 3–6 mm, glabrous or sparsely pubescent.
beige to bronze, 1.3–2 mm.
purple, sometimes streaked with light and dark brown, 1.5–2.5 mm.
= 20.
Viola rostrata
Viola biflora
Viola rostrata has the longest spur of any North American Viola species.
Viola rostrata reportedly hybridizes with V. labradorica (= V. ×malteana House) and V. striata (= V. ×brauniae Grover ex Cooperrider).
(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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