Heath Dog Violet and hybrids in New Forrest

Heath Dog Violet ( Viola canina) and hybrid with Pale Dog Violet.  New Forest. May 2015
The new Viola BSBI Handbook has been published and gives a good baseline for all the species and hybrids that occur in Britain and Ireland. It has the advantage of comparing the hybrids against the  parent species in table form, which the detailed coverage in the 'Hybrid Flora of the British Isles ' does not do, as it only covers hybrids.  Written by the same Mr Porter and Mr Foley the combination of both books gives much useful information and the key warning that violets have weak barriers to hybridisation.  It would now appear that a small percentage of hybrids are fertile and 'introgression may occur more widely than has been previously thought".

My previous attempts to find Heath Dog Violet have been searching Newmarket Heath in Cambridgeshire, where they are effectively gone and at Lough Allua in West Cork where hybrids with Pale Dog Violet ( V. lacteal) and Common Dog Violet ( V. riviniana) make finding a 'pure' example hard but not impossible.
An attempt to find Heath Dog Violet in the New Forrest started well but walking down the track I found paler and paler flowers which raised the possibility that  I was looking at hybrids with Pale Dog Violet.

Side view .
21st May 2015,  New Forrest.  Very large sepal appendages seem a consistent feature along with the pale greenish yellow spur colour. Looks good for Heath Dog Violet ( V. canina).

Front view ,
showing very thin veins on the lower petal which extend well down the length and no sign of the darker band at the edge of the white throat that V. riviniana often has.

Third photos a little further down the track shows a paler flower but flowers of intermediate colour were present. This photo was the palest found. It was going so well but.....

Final New Forrest shot from 21st May 15 shows pale flower and leaf shape tending towards Pale Dog Violet.  Concluded better retreat and look for pure Heath Dog Violet somewhere else. With more time it would have been interesting to check out these intermediate coloured plants to determine if they are hybrids and also if Pale Dog Violet were present. They were not showing any vigorous tendency which is often looked for in the hybrid.  

Peter Leonard.   24th April 2017