Notes on the biology of some native orchids of Thunder Bay, their endophytes and symbionts

Field studies were made of eight terrestrial orchid species of the Thunder Bay region during their active growing period. In four of them roots were examined for infection, then isolation and identification of endophytes attempted.Seeds were collected from all species and, along with those of two alien ones, were grown on various media in axenic culture. Their germination and development were studied and described.Seeds were also tested in dixenic cultures with locally isolated endophytes and four fungi known to be good symbionts with other orchids. The nature of infection was finally assessed and discussed.In the field the roots of mature plants of the orchid species differed in their degree of infection and reaction to their endophytes. Only two species of Rhizoctonia were isolated. These are described.In axenic culture, germination of some species was affected by the organic (and inorganic) components of the media, in others it was not. For growth they all responded differently to such components, but most were intolerant of casamino acids, yeast extract, and potato extract. Generally there seemed to be a direct correlation between percentage of germination and amounts of subsequent growth, but a less defined one with the number of cells per seed.In dixenic cultures the orchids responded differently also to the fungi. Their reaction to infection had no relation to their ability to germinate on poor media or to germinate and grow on richer ones. Only one good symbiotic association was established. It was between Goodyera oblongifolia from British Columbia and Rs10, a rice pathogen from Malaysia.The results and their implications are briefly discussed.