Long-term study of the Sword-leaved Helleborine Cephalanthera longifolia (Orchidaceae) in Knapdale, Argyll

Abstract

The results of detailed monitoring of four populations of Sword-leaved Helleborine, Cephalanthera longifolia (L.) Fritsch over a 22-year period at Knapdale, Argyll are presented. Flowering and vegetative plants were recorded each year, with individuals relocated using triangulation. There were marked differences in the population changes at the four sites with the likely causes being grazing and changes in light intensity. In addition, a few large plants were recorded over a 31-year period. A few, large, plants flowered for the majority of the study and were probably of disproportionate importance to the long-term survival of the plant at Knapdale. The flowering, survival and occurrence of the other plants varied considerably. In addition, observations from other sites in Knapdale were noted.