The cell wall fine structure of the red alga Palmaria palmata has been analysed extensively in recent years, but cell wall biosynthesis has not. The glycosidic composition of the cell walls of gametophytic and sporophytic fronds revealed no differences between the two stages. Spores were isolated from mature sporophytes and cultivated in vitro. Spore settlement, germination and first stages of germling development were described in terms of glycoside composition. Isolated spores were surrounded by a cell wall composed of xylose, galactose and glucose. During germination and germling development, the xylose content increased to the level of glycosides found in erect fronds, concurrently with starch degradation. Spores isolated from Palmaria palmata appeared to be good candidates for studying cell wall biosynthesis.