Isozyme analysis of the origin of a new endemic orchid species, Epipactis youngiana, in the British Isles

A survey of isozyme variation in what has been recorded as a new hybrid orchid species in the British Isles, Epipactis is youngiana (Young's helleborine), and its putative parent species, has cast doubt on its supposed origins, i.e. stabilization of a hybrid product via autogamy after hybridization between E. helleborine x E. leptochila or E. helleborine x E. phyllanthes. Contrary to expectation, E. youngiana was found to contain a high level of genetic diversity and a genotypic structure indicative of outcrossing. Moreover, at a Glasgow site it appears to be interbreeding with two of its putative parents, E. helleborine and E. leptochila, to form part of a hybrid swarm. From the isozyme data, it is possible to dismiss the idea that E. phyllanthes may have acted as a parent of E. youngiana; however, it cannot be ruled out that the 'new species' is merely a variant form of E. helleborine or an introduction rather than a product of hybridization.