SUMMARYThe diatom floras of some calcareous spring and stream samples in a small watercress‐growing area have been examined. Plants and sediments from the springs, and plants, sediments and stones from the streams have yielded a total of 123 diatoms, divisible into distinct communities, the composition of which is discussed. The sediments yield a large number of species with several species co‐dominant. The epilithic samples are poor in species with generally a single dominant. The Rhodophycean algaBatracko‐spermumsupports a very sparse epiphytic flora, whereas that on mosses, in algal felts and on water plants is richer. Comparison is made with data from Denmark, Hungary and the Ba