Flower:

Single flowers on naked stalks arising from the leaf axils. Flowers are about 1 inch across, slightly irregular with 5 white petals, distinctly yellow at the base, and dark purple lines on the lower petals. The side petals are “bearded” with tufts of short hairs. The backs of the petals are tinged purple.

Leaves and stem:

There are both basal and stem leaves, mostly heart-shaped, 2 to 4 inches long and to 3 inches wide, with scalloped or shallowly toothed edges and sharply pointed tips. The stem leaves are typically more elongated than basal leaves. There are fine hairs on leaf edges and along major veins on the underside. Stems are hairless or have a few scattered hairs and often tinged purple.

Notes:

Canadian White Violet often grows in clumps. I've read it spreads easily in a garden setting. When not blooming the leaves can be mistaken for Viola pubescens (Downy Yellow Violet), but the latter leaves are typically smaller, mostly wider than long, and more strongly toothed.