ISOZYME ANALYSIS OF THE REPORTED ORIGIN OF A NEW HYBRID ORCHID SPECIES, EPIPACTIS-YOUNGIANA (YOUNGS HELLEBORINE), IN THE BRITISH-ISLES

A survey of isozyme variation in what has been recorded as a new hybri d 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. helle borine x E. phyllanthes. Contrary to expectation, E. youngiana was fou nd to contain a high level of genetic diversity and a genotypic struct ure indicative of outcrossing. Moreover, at a Glasgow site it appears to be interbreeding with two of its putative parents, E. helleborine a nd E. leptochila, to form part of a hybrid swarm. From the isozyme dat a, it is possible to dismiss the idea that E. phyllanthes may have act ed as a parent of E. youngiana; however, it cannot be ruled out that t he 'new species' is merely a variant form of E. helleborine or an intr oduction rather than a product of hybridization.