Floral Phenology of a Stand of Mountain Ash (Eucalyptus regnans F. Muell.) In Gippsland, Victoria

Abstract

Flowering phenology was observed in a stand of Eucalyptus regnans F.Muell. at Narracan, Gippsland, Vic. during 1977 and again in 1979. The first tree flowered on 15 February in 1977 and on 30 January in 1979. Flowering of all trees was completed after 90 and 100 days respectively, and in both seasons the modal value for the number of trees concurrently in flower occurred 40 days after commencement. There was a highly significant association, between years, for the relative time and duration of flowering of individual trees. Tree size was not an important determinant of flowering attributes. Trees were not randomly distributed with respect to peak flowering time: thus flowering of adjacent trees tended to be synchronous. Detailed observation of flowering within the crowns of three trees showed that within inflorescences the mean period between anthesis of the earliest and latest flowers was 6 days, and within branches 14 days. The degree to which flowering was synchronous within the crown varied consistently between trees at each structural level assessed, which suggested genetic control of this trait. Implications of the floral phenology for the breeding system and gene flow of the species are discussed.