It is clear that in Japan there are at least two races of Triglochin maritimum in a wide sense. The northern race is very similar in outer morphological characters to a common form of T. maritimum L. of Europe, but it is a high polyploid with 2n=120 chromosomes. The other race distributed in western Japan, however, has scapes often shorter than soft elongate leaves, and narrow oblong capsules with recurved style and small stigma, and it is, contrary to Löve's presumtion, the same as the European one in the number of chromosomes (2n=48). Subsp. asiaticum Kitagawa described from south Manchuria has never been studied cytologically.