375 Lemna minor L.

This species is almost cosmopolitan in its distribution. See world map in Meusel et al. 1965, p. 81. It belongs to the circumpolar plants (Hultén, Circumpol. I, p. 130 and map 121). Recently, a rather similar species, L. minuscula Herter (syn.: L. minima Phil.) is recorded as introduced into Europe (England France, W. Germany, Switzerland) from N. America (Landolt in Ber. Geobot. Inst. ETH, Stift. Rubel, H. 76, Ziirich 1979).