Heath Dog Violet ( Viola canina) Norfolk

Heath Dog Violet ( V. canina)  The search continues.

Armed with the new BSBI Viola Book (recently published ) I though it was time to find some pure 100% Heath Dog Violets.  I had noticed that the BSBI map was showing a few dots on the Norfolk coast in an area where I have been birdwatching in the past. The sand dunes just west of Holkham Pines is a great place  and good for a walk. Late April is a bit early for Heath Dog Violets but on arrival on 23rd April there were several hundred plants scattered over the dunes.  Not having seen violets in a dune habitat I was surprised how small the plants were, tiny leaves but almost normal size flowers.

23rd April 2017, North Norfolk Coast TF856458.  Side view showing the pointed sepals having large sepal appendages, short pale yellow spur and small leaves.

23rd April 2017.  Lower petal showing thin but very clearly defined veins. In full thickness they only continue about half way down the petal but they do continue very faintly almost to the end. No darker terminal band to the white throat. Pale yellow spur just showing and tiny leaves.

Habitat photo. Soil almost pure sand. No competition from grass yet.

This next shot shows the leaf. The largest leaf seen was only 12mm long and 7mm wide, many much smaller. Shape not typical in that only a few were seen with cordate ( heart -shaped) bases or the squared off base of more triangle shaped leaves. No basal rosette  of leaves present which was easy to see on plants growing in pure sand without any other plants around them. Thick with shallow crenate edges.    I was happy these were 100% V. Canina as all the plants looked the same without any variation.  There again nothing is 100% in Violets.

Final photo shows stipules with mainly forward pointing teeth (fimbriae) which are quite thick. In comparison a Common Dog Violet has stipules which have thinner fimbriae more hair like than tooth shaped and tend to stick out at right angles to the stipule (although some do point forward).
Leaf base on right showing slightly cordate (heart shaped) base. Due to the very small size of all the leaves at this site none seemed to have the triangular  shape often seen with Heath Dog Violet growing on better ground.

Peter Leonard.  26 April 2017

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