This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Viola pubescens Ait. Hort. Kew. 3: 290. 1789.
Softly pubescent; stems mostly stout, 8'-12' high, often solitary; leaves either cauline, 2-4, near the summit, short-petioled, or occasionally a long-petioled root-leaf; blades broadly ovate or reniform, with cordate or truncate-decurrent base, crenate-dentate, somewhat pointed; stipules large, ovate-lanceolate; sepals narrowly lanceolate; petals bright yellow, the lateral bearded, the lower with short spur; capsules ovoid, 5"-6" long, ovoid-conic, glabrous or sometimes woolly; seeds brown, 1 1/4" long.
Often widely spreading from long, thick, branching stolons; stems stout, 1°-2° high"; radical leaves usually 3-5, long-petioled, the blades cordate-reniform, abruptly short-acuminate, often 4' wide, densely hirsutu-lous beneath, sparsely so along the veins above; lower stem-leaves similar, the upper successively smaller and shorter-petioled, the blades becoming ovate-acuminate, the puberulence of the lower surface extending along the petioles and upper part of the stem; stipules lanceolate, nearly entire; flowers and fruit as in V. canadensis; petal-iferous flowers often appearing in summer and autumn.
Rich woodlands, Iowa and Minnesota, west to the Rocky Mountains. May-Oct.
Viola canadensis L. Sp. Pl. 936. 1753.
Usually 8'-16' high, glabrous or but sparsely and minutely pubescent; leaves broadly ovate, cordate, acuminate or acute, serrate; stipules sharply lanceolate; flowers single from the axils of cauline leaves, often appearing throughout the season; sepals subulate, spreading; inner surface of petals white above, bright yellow at the base, the outside more or less tinged with violet, the three lower striped with fine dark lines, the lateral pair bearded; capsules ovoid to subglobose, 3"-5" long, often downy or puberulent; seeds brown, 1" long.
In mountain forests or wooded uplands, New Brunswick to Saskatchewan, south to South Carolina, Alabama, Nebraska, and in the Rocky Mountains to Arizona and New Mexico. Ascends to 4000 ft. in Virginia. American sweet violet. Hens. June-flower. May-July.
Viola striata Ait. Hort. Kew. 3: 290 1789.
Stems several, angular, leafy, ascending, 6-12' long when in flower, in late summer often 2° long, decumbent; leaves glabrous or nearly so, orbicular to ovate, cordate, 1'-1 1/2' wide, usually acuminate, finely crenate-serrate; stipules large, oblong-lanceolate, fimbriate; flowers long-peduncled; sepals cilio-late, linear-lanceolate, attenuate; corolla white or cream-colored; spur thick, blunt, about 2" long; style somewhat bearded below the beak; capsules ovoid, glabrous, 2"-3" long; seeds light brown.
Low and shady ground, New York to Minnesota, south to Georgia and Missouri. Ascends to 3000 ft. in Virginia. April-May.