Abstract
In contrast to their dominance on land, few angiosperms occur in the aquatic environment, and even fewer have adapted to living in the marine and brackish environment. In this paper, species richness in fresh, brackish and marine habitats is reviewed briefly, and the results of comparison of species richness between 3 brackish lakes and their inlet rivers are described. In Japan, there exist 15 seagrass species and only 7 species are recognized as brackish inhabitants.
