Downy yellow violets are one of my favorite woodland violets. The heart-shaped leaves set off the bright yellow flowers in early spring. Because of its short stature (6-12"), I use this violet on woodland borders, intermixed with Pennsylvania sedge, rue anemone and virginia waterleaf.
Other visitors of downy yellow violet include bee flies (Bombylius sp.), clouded sulphur butterflies (Colias philodice) and Syrphid flies.
Beattie, A. J. (1974). Floral evolution in Viola. Annals of the Missouri Botanical Garden, 781-793. Retrieved from: http://www.jstor.org/stable/2395029