Newcomb's Wildflower Guide lists over 30 Viola species occurring in Northeastern and North-central North America.
This was the first day of our monitoring season. There wasn't much blooming, but for me, the Birdfoot Violet makes any trip worthwhile. We counted over 300 plants blooming on the sand dunes just off Ostrich Lane.
The Sand cherry had enough buds for us to count it as well.