Flower:

Single irregular 5-petaled flower at the end of a naked or sparsely hairy stem that typically rises above the leaves. Flowers are white with a greenish throat, up to ½ inch (≤ 13 mm) long. The upper two petals are erect or bent back, the two lateral petals have short hairs at the base (bearded), the lower petal is hairless, has purple veins near the base, and forms a short rounded spur at the back.

The 5 sepals around the base of the flower are hairless, the two lower largest, lance to egg-shaped, rounded to blunt at the tip, and have a short extension at the base (auricle) that is straight across to rounded along the end and does not elongate in fruit.

Leaves and stems:

Leaves are all basal, held ascending to spreading, heart to kidney-shaped, usually rounded to blunt at the tip, with deeply cleft basal lobes that may be overlapping when young but tend to separate with age, forming a broad sinus. Largest leaves are up to about 2½ inches (61 mm) long, about as wide or slightly wider.

The upper surface is hairless or sparsely to moderately hairy, the lower surface usually hairless. Edges have shallow teeth and lack a fringe of hairs. Leaf stalks are hairless to sparsely hairy.

In mid to late summer above ground stems (stolons) are produced that are very slender, often naked or may have a leaf or two along its length, sometimes also fruiting capsules but usually not. The stolon ends in a new plantlet.

Fruit:

Both petalled (chasmogamous) and petal-less, self-pollinating (cleistogamous) flowers produce fruit, in a hairless, ovoid capsule that is initially nodding, becoming erect just before splitting into 3 sections and releasing its seed. Chasmogamous capsules are typically green. Chasmogamous flowers bloom in spring. Cleistogamous flowers are produced all summer into fall on prostrate stalks much sorter than the leaf stalks and arch up just before seed release; capsules are up to ~1/3 inch (5 to 9 mm) long and green or purple spotted.

Seeds are light to medium brown, up to about 2 mm long.

Notes:

Sweet White Violet is one of the most common violets in Minnesota, primarily found in shady woods and swamps in moist to wet soil, but tolerates drier conditions as well. It can perform spectacularly in a cool shady corner of the home garden. In Minnesota, this was previously known as Viola blanda, but a major overhaul of Viola accounts published in 2023 has put V. blanda firmly in the east, from the southeastern corner of Indiana to northern Georgia and north through New England. V. incognita has taken its place elsewhere. I was actually somewhat relieved at this change, since plants I encountered never seemed to quite match up with V. blanda descriptions of usually hairless all over, dark brownish-black seeds, beardless flowers and the supposed twisting of the upper petals, which I could never quite see.

V. incognita is recognized by: not more than about 6 inches tall; all basal leaves held ascending to spreading, blades up to 2½ inches long and about as wide, heart to kidney-shaped, shallowly toothed, frequently at least sparsely hairy on the upper surface, though may be more or less hairy; leaf stalks and flowering stems often sparsely hairy; white flowers about ½ inch long, lateral petals short-bearded, beardless spur petal, short spur; thread-like stolons produced in summer, usually naked or with a leaf or two.

It is most easily confused with Viola miniscula (Northern White Violet, formerly V. macloskeyi or V. pallens) and Viola renifolia (Kidney-leaved Violet). V. miniscula leaves are hairless, the edges have more rounded teeth, sometimes stalks are sparsely hairy; flowers are usually beardless; seeds are medium to dark olive brown; stolons have multiple nodes with leaves and cleistogamous capsules. V. renifolia leaves are typically prostrate to spreading, the upper surface shiny, both surfaces variably hairy from hairless to dense; flowers usually beardless; seeds are light to medium orange-brown to brown; no stolons are produced; frequently found in rocky soil.