ECOTYPIG DIFFERENTIATION OF CALLUNA VULGARIS (L.) IN RELATION TO ALTITUDE

Abstract

Population studies of Calluna vulgaris (L.) were undertaken in order to investigate plant variations genotypic in origin. Seed was collected from ten widely separated areas in Great Britain and seedlings from each population were grown in a spaced plant trial. In a later study plants were raised from seed collected at high and low altitudes from within sixteen centres in Scotland. Data were collected on growth habit, flowering and frost resistance. The results indicate that ecotypic differentiation occurs and that the pattern of differentiation is ecoclinal. (i) Variation in growth habit is continuous and the proportions of the various growth forms change with change in altitude. (ii) Maturity type is related to the length of the growing season at the site of origin of the population. Populations originating from areas having shorter growing seasons are composed of individuals of an earlier maturity type than those from areas where the season is longer. (iii) Observations on frost damage were made in the first study. The numbers of susceptible plants were too low to permit population comparison but susceptibility could be related to soil and climatic variation. The significance of the variational trends is discussed. Copyright © 1962, Wiley Blackwell. All rights reserved