A Different Violet

Looking closer at the violets in the garden, I noticed that I have two different species. Alongside the Common Dog Violet (Viola riviniana, #26), I have Wood Dog Violet (Viola reichenbachiana, #556). This is sometimes also called Early Dog Violet, but it doesn’t seem to flower much earlier than Common. The easiest identification feature is to look st the spur at the back of the flower, which is white in the Common Dog Violet but the same purple colour as the flower in Wood Dog Violet. Putting the two side by side there are other more subtle differences in the flowers and the leaves: in my garden the leaves & stems of the Common Dog Violet have a purple tinge and the leaf edges are also different. The white form I found on a walk around the local woodland seems to be Common Dog Violet.