A study was made of the floristic composition of the forest vegetation, including the rocks and peatlands, in four study areas, two of which were on the coast, two inland. The frequency of the different species is expressed as an estimate of the area occupied by the stands of the species in relation to the total area. Lists of plant species were made every 50 m on survey lines 5 m broad. The number of such plots (5 × 50 m) on which a species was recorded in relation to the total number of plots is regarded as an estimate of this coverage. Once estimates of the commonest species had been made in the Korso area, these were left unrecorded and only the rarer plants were noted; in this way the field work was considerably reduced and the method became rather similar to the usual excursion method. Several suggestions on the method are proposed. Marked differences in frequency were found between the coast and the inland areas, in particular in the case of the dominant plant species (table 2). After a discussion of several factors the hypothesis is advanced that the climate in the coastal areas, which is thermally more oceanic but at the same time deficient in summer rains, may be the main cause of this distribution pattern. Additional factors are the different biotope frequency on the coast (in particular the abundance of rocks and slightly smaller area of fertile biotopes), and in some cases also the prescribed burning earlier practiced and also pure chance.