ENVIRONMENTAL PARAMETERS INFLUENCING THE DISTRIBUTION OF PLATANTHERA-BLEPHARIGLOTTIS AND PLATANTHERA-CLAVELLATA (ORCHIDACEAE) IN PEATLANDS ON THE AVALON PENINSULA, NEWFOUNDLAND

Populations of two terrestrial species of orchids, Platanthera blephar iglottis (Willd.) Lindl. and Platanthera clavellata (Michx.) Luer, wer e investigated for two field seasons (1991-1992) to determine what env ironmental factors (substrate constituents, water pH, water level) may influence their distributions within a peatland. Feat constituent val ues (magnesium, phosphorus, nitrogen, potassium, iron, calcium, pH, mo isture, organic matter, ash) associated with individual species were, for the most part, not significantly different among sites or between species, although the values associated with P. clavellata tended to b e higher and to have a greater range than those associated with P. ble phariglottis. Water level values associated with species were signific antly different between species, suggesting that it is on this basis t hat these species partition their habitat.