VARIATION OF SOME DIAGNOSTIC CHARACTERS OF THE SESSILE AND PEDUNCULATE OAKS AND THEIR HYBRIDS IN SCOTLAND

Abstract

A collection of Scottish oaks including nearly 1,000 fertile specimens has been analysed in respect of selected diagnostic characters. Pictorialized scatter-diagrams confirm that only two taxa are involved and that considerably more than half the fertile material cannot be diagnosed with confidence as belonging to either. The variation patterns within population samples are so exactly what would be expected from widespread and massive introgression that the objections to this interpretation are called into question. All the robur-dominated woods appear to be quite strongly introgressed but there are a few petraea woods which are relatively homogeneous and show no evidence of introgression. The latter are used to demonstrate the variation that may be expected from reasonably good petraea in Scotland.