Catapodium marinum (L.) Hubbard is found growing in the Netherlands in the Slufter on the isle of Texel and in the inundated (flooded) Zwarte polder in Zeeuws Vlaanderen. An investigation was made on how the grass, that grows in the Netherlands on the northern boundary of its area, maintains itself. To that purpose a part of the habitat in the Zwarte polder was provided with marks. On these spots the development of the seed into the flowering plant was observed for the period of two years. It appeared that normally the seed germinates in the months of August/September and that the young plants have grown to thoroughly stooled plants before the setting in of the winter; in this stage they are able to hibernate when the winter is not too severe. A small percentage of the seed germinates not before spring, and the plants originated from this seed as a rule have only one flowering stem with few, small spikelets. After the severe winter of 1955/56 on the marked spots one-stemmed plants were found exclusively, from which fact it may be concluded that the plants of the preceding autumn had not outlived the severe cold.