AbstractSphagnum pylaisiiBrid. occurs in north-western Spain in areas with mean annual precipitation exceeding 1500 mm. It is characteristic of denuded places in acid fens on shallow peat, generally over granitic bedrock. Water stays above ground-level in winter but may drop below−50 cm in summer. A comparison with its habitat in Brittany, France and Northern America is made. Its distribution in Northern Spain and Europe is illustrated.