I have a plant with rose flowers that was sold as Viola adunca. I suspect that it is the rose form of V. riviniana. Does someone know a definitive character that will distinguish the two?
See if you can find the difference in the spurs. V. adunca has a blunt, sometimes slightly hooked spur, whereas V. riviniana often has a notched paler spur: http://upload.wikimedia.org/wikipedia/commons/5/50/Viola_adunca_1126.JPG http://upload.wikimedia.org/wikipedia/commons/d/d6/Viola_riviniana.jpeg
Yes, the weedy, rose-colored, fading form of V. riviniana is mis-called V. adunca in this region. I once even had a vendor at a local plant sale tell me a botanist at the University of Washington had confirmed - or identified originally - (the stock of obvious V. riviniana) she was presenting as V. adunca. In addition, V. riviniana 'Purpurea' continues to be sold as V. labradorica or V. labradorica 'Purpurea'.
