The Influence of Fruit and Bud Volumes on Eucalypt Flowering—An Exploratory Analysis

Abstract

The appearance of buds and development of fruits in 51 species of Eucalyptus L’Hér. were examined to determine whether bud and fruit volume had an influence on flowering. These variables exert an influence on eucalypt flowering as individuals and as members within an umbel. Flowering earlier in the growing season is characteristic of species with large, individual bud and fruit volume and those that have a large umbel volume. The number of buds and fruits in an umbel is influenced by volume of the individuals. Development time of buds was longer in umbels which had a larger total volume. Bud and fruit umbel volume was positively correlated with the timing of bud appearance as was seed maturity with individual fruit and fruit umbel volume. A threshold of bud and fruit volume was indicated below which seed maturity and time of flowering is not reflected by volume. Discriminant analysis used nine predictors to assign 80% (overall) of section members of Adnataria (91%), Bisectaria (60%), Maidenaria (67%) and Renantheria (87%) to their true groups. Across groups examination adduced the possibility of each group having a distinct bud development period and a discernible cessation of flowering. Five clusters were revealed whose members were significantly differentiated on seed maturity, section, individual fruit volumes, bud and fruit umbel volumes. Factor analysis outlined four factors—buds, fruits, timing and development—which accounted for 78.9% of the variance.