Viola rupestris and its hybrids in Britain.

Hybrids between Viola riviniana and V. rupestris were identified by means of isoenzymes from three of the four localities for V. rupestris known from Britain. Differentiating characters between V. riviniana and V. rupestris are primarily found in leaf shape and indumentum, flower colour, spur shape and capsule shape. The ecology of V. rupestris is presented and compared with that of the hybrid and V. riviniana.