Flower:

The irregular flowers are ¼ to ½ inch wide and solitary at the end of a leafless stalk that can be either hairy or smooth, and is usually shorter than the leaf stalks. The 5 petals are white with brown-purple lines on the lower 3 petals, fewer on the lateral petals. The petals may be hairless or have a small tuft of short hairs near the base (bearded); all petals or just the lateral petals may be bearded. The spur at the back of the flower is rather short and rounded.

Leaves and stems:

Leaves are all basal, mostly kidney shaped (hence the common name) during flowering, the tip bluntly pointed or rounded, the largest leaf blades broader than long, ¾ to 2 inches wide, becoming more heart-shaped after the flowering period, enlarging up to 3½ inches long and wide. Leaf edges have shallow, rounded teeth. Both leaf surfaces as well as the stalk can be variously hairy, or the upper leaf surface smooth with scattered hairs below or occasionally hairless throughout. Above ground runners (stolons) are absent.

Notes:

Of Minnesota's 6 white violet species Kidney-leaved Violet is most easily confused with Small White Violet (Viola macloskeyi), which shares the same general habitat. From our experience, the more rounded leaf tips that give this species the name “kidney-leaved” is not really apparent as both species can have both have rounded and blunt tipped leaves, and both may have bearded or beardless flowers. Better distinguishing characteristics are sizes of the leaves and hairiness of leaf surfaces and stalk. V. macloskeyi leaves rarely get much bigger than 1½ inches long or wide, and may have scattered hairs but is usually all hairless and, while V. renifolia can be hairless, it usually has some hairs. Perhaps the best distinguisher, that requires observation of the entire plant, is that V. macloskeyi spreads by thread-like, above ground runners (stolons) and in V. renifolia these are always absent. Of note is that some references state the petals of V. renifolia are either all bearded or all not, but we have not seen this out in the field.