Viola sororia albiflora
Violet family (Violaceae)
Description: This is a herbaceous perennial plant with the leaves and flowers emerging directly from the rhizomes, and forming a basal rosette. A typical mature plant may be 6" across and 4" high, with the flowers slightly higher than the leaves. The leaves are individually up to 3" long and 3" across (excluding the long petioles), and vary in color from pale green to dark green, depending on growing conditions. They are oval-ovate to orbicular-cordate, and crenate or serrate along the margins. The foliage is glabrous to slightly pubescent. The flowers are about ¾" across, and consist of 5 rounded petals. There are 2 upper petals, 2 lateral petals with white hairs (or beards) near the throat of the flower, and a lower petal that functions as a landing pad for visiting insects. The flowers of this form of Viola sororia are white to mostly white, except for violet lines radiating from the throat of the flower (particularly the lower petal). There is no noticeable floral scent. The blooming period occurs from mid- to late spring and lasts about 1-1½ months. During the summer, cleistogamous flowers without petals produce seeds, which are flung outward by mechanical ejection from the three-parted seed capsules. The root system consists of thick, horizontally branched rhizomes; there is a tendency to form vegetative colonies.
Cultivation: The preference is partial sun or light shade, and moist to mesic conditions, although full sun is tolerated if there is sufficient moisture. The soil should be a rich silty loam or clay loam with above average amounts of organic matter. This plant is easy to grow, and it will spread under favorable conditions.
Habitat & Range: The native White Wood Violet is occasional to locally common in Illinois; because it is (or was) considered a mere color form of Viola sororia, a Distribution Map is currently unavailable. Natural habitats include open woodlands, woodland borders, savannas, and wooded slopes along rivers or lakes. In more developed areas, it is sometimes found in city parks, lawns, and along hedges or buildings. It is often found in close proximity to Viola sororia sororia (Common Blue Violet).
Faunal Associations: The flowers have few visitors (hence the need for cleistogamous flowers), but sometimes they attract bees and other insects. The species Andrena viola (Violet Andrenid Bee) is an oligolectic visitor of Viola spp. (Violets). The caterpillars of many Fritillary butterflies feed on the foliage of violets, including Speyeria diane (Diana), Euptoieta claudia (Variegated Fritillary), Speyeria aphrodite (Aphrodite Fritillary), Boloria bellona (Meadow Fritillary), and Boloria selene myrina (Silver-Border Fritillary). Some seeds have soft appendages that attract ants, which help to distribute them. Various upland gamebirds and small mammals occasionally eat the seeds, including the Wild Turkey, Bobwhite, Mourning Dove, and White-Footed Mouse. Wild Turkeys also eat the leaves and fleshy roots of violets. Although it is not a preferred food source, mammalian herbivores occasionally eat the foliage, including the White-Tailed Deer, Cottontail Rabbit, and livestock.
Photographic Location: The photographs were taken of plants growing along the edge of a yard in Urbana, Illinois.
Comments: The White Wood Violet is the white form, f. albiflora, of Viola sororia. The typical form of this species, Viola sororia sororia (Common Blue Violet), which is more common, has medium to dark violet flowers. Generally, the White Wood Violet doesn't appear to spread as aggressively as the typical form of this species; it is equally attractive and its light-colored flowers are more conspicuous in shady areas. Some authorities (e.g., Mohlenbrock) combine the White Wood Violet with Viola sororia priceana (Confederate Violet) and regard the two of them together as a distinct species, Viola priceana. However, I disagree with this taxonomic revision and prefer to regard them as distinct color forms of Viola sororia at the present time. This corresponds to the taxonomic classification of the American Violet Society.