Variation in Leaf Waxes of the Tasmanian Eucalyptus Species - I. Subgenus Symphyomyrtus

Leaf waxes were analysed from juvenile and adult leaves collected from natural populations of all Eucalyptus species from the informal subgenus Symphyomyrtus native to the island of Tasmania. Four species were from the series Ovatae (Eucalyptus barberi, E. brookeriana, E. ovata, E. rodwayi) and 13 were from the series Viminales (E. globulus ssp. globulus, E. vernicosa, E. subcrenulata, E. johnstonii, E. viminalis ssp. viminalis, E. dalrympleane ssp. dalrympleana, E. rubida, E. gunnii, E, archeri, E. morrisbyi, E. urnigera, E. perriniana and E. cordata). The major classes of compounds identified from hexane soluble leaf waxes were long chain hydrocarbons, aldehydes, alcohols, esters and β-diketones; flavonoids and triterpenoids. Long chain β-diketones were the major components of hexane soluble waxes of the majority of species, but some species had high proportions of long chain hydrocarbons, aldehydes or triterpenoids. Cluster analyses based on the percentage composition of leaf waxes resulted in the majority of populations of the Tasmanian Symphyomyrtus species clustering according to species with excellent differentiation of many species within series. The chemical composition of leaf waxes of juvenile and adult leaves was qualitatively similar for most components and no significant quantitative differences were detected in most species. The relative ontogenetic stability of wax composition, coupled with the often clear differentiation of species, indicates the usefulness of biochemical markers derived from leaf waxes for taxonomic and phylogenetic studies in the genus Eucalyptus.