Pilularia globulifera L. (Pilvaren) in Zuid-Holland

Pilularia globulifera is restricted to Europe. It has a scattered distribution and in the most parts it is considered vulnerable or endangered. In the Netherlands it seemed confined to sandy or loamy soils in pleistocene and dune areas. In 1987, however, it was found in a ditch on acid clay (kattenklei) in the province of Zuid-Holland. This ditch is strongly influenced by seepage water. Relevées 2 and 3 show the vegetation of the margin of the ditch (nr. 2) and the ditch proper (nr. 3). In 1995 Pilularia was discovered near Berkenwoude in a former meadow of which the top layer (about 25 cm) was removed in 1994. Here it grew on peat in an area in which rainwater infiltrates. Relevée 1 was made on the latter locality.