ABSTRACT: Morphological development of Laminaria hyperborea was examined at localities with different degrees of wave exposure. Biomass data were converted to estimates of annual growth of lamina, stipe and hapteron. Allocation of annual growth to thehapteron constituted a small amount of the total production, but increased with increasing wave exposure. At the most sheltered locality, lamina growth amounted to between 80 and 95% of total growth in all age groups, and lamina to stipe ratios (freshweight) were about 10. A higher portion of the annual growth was allocated to the stipe at the more wave-exposed localities. This resulted in lamina to stipe ratios of between 1 and 2 in old plants, but within these localities no gradual decrease inlamina to stipe ratio with increasing wave exposure was observed. At some localities a maximum of growth allocation to the stipe was found in the intermediate age groups. This was most pronounced at the locality with the highest density of canopy plantsand intermediate wave exposure. Also, at this locality the stipes were longer in relation to their weight than at the other localities. These results indicate that light environment, in addition to wave exposure, may influence the stipe morphology and therelationship between stipe and lamina growth. At one station stipe growth was also calculated in individual tagged plants using the length-weight relationship. The results agreed with those obtained by the biomass method. The highest allocation of growthto the stipes was found in 3 and 4 yr old plants. Maximum annual stipe growth (weight increase) occurred in 4 and 5 yr old plants and decreased in older plants, while maximum lamina growth was found in the oldest plants.