The vegetation associated with Spiranthes romanzoJJiana Cham. (Orchidaceae), Irish Lady's-tresses, on the Isle of ColI, Inner Hebrides

This paper details some environmental preferences of the scarce orchid Spiranthes romanzojfiana Cham. on the Isle of Coli in the Inner Hebrides. Samples were categorised into four site types that form a continuum rather than a series of discrete habitat types. High cover of Carex panicea L., and to a lesser extent Molinia caentlea (L.) Moench and Jun cus articulatus L., occurs throughout. The habitats appear to be influenced by varying degrees of high water and low nutrient ava il ability, as suggested by the disparate spec ies. There is no apparent difference between former and present habitat of the orchid on the island, but few conclusions can be made from vegetation description alone. As it stands, the habitat as defined in this study is not uncommon, and it may be that other factors. such as seed sterility or availability of mycorrhizal associate, are limiting the species distribution