Sand violets are closely related to common violets. Or, according to some, they are common violets. When I first found this in 1987, I sent a specimen to MICH (the University of Michigan Herbarium). They sent back a note that it was V. sororia, the common violet. But some time later, I got another note that a violet expert had examined their collection, and determined that this was V. affinis. The staff there have been incredibly generous helping with my collections. Particularly Dr. Anton Reznicek and the late Dr. Ed Voss. Very much appreciated.