Chemotaxonomy of the genus eucalyptus

Chemical characters in the majority of the Tasmanian species of Eucalypts have been investigated to determine their value to the taxonomy of the genus. The investigation has included three classes of chemicals. 1. The leaf and twig bark anthocyanins of each of twenty-two species were isolated and identified; it was found that anthocyanin distribution generally paralleled the split of the Tasmanian Eucalypts into two sections, namely, Sections Macrantherae and Renantherae. Cyanidin compounds containing glucose are the most widespread in the genus, other anthocyanidins found being delphinidin, malvidin and peonidin. The anthocyanin pattern of the Macrantherae is generally simple, and is based on the 3-glucoside and 3,5-diglucoside of cyanidin. The Section Renantherae, is further subdivided into two groups on the basis of the distribution both of the galactosides of cyanidin and delphinidin and of the methylated anthocyanins ~ this division parallels that based on morphological characters. The anthocyanin patterns of some renantherous species, (E. coccifera, E. risdoni and E. tasmanica) reflects the simplicity of the patterns found in macrantherous species. 2. Other flavonoids in leaf and twig bark were classified according to their Rf values in different solvent systems. Certain aglycones and alcohol-soluble polyphenols were restricted to either section or to groups within these sections. Again, these divisions agreed with morphological classification excepting for E. coccifera. 3. Protein and isoenzyme patterns of seedlings of the twenty-two species were obtained. Peroxidase and esterase patterns were useful in showing taxa relationships. All macrantherous species, except E. aggregata showed similar peroxidase patterns, while E. aggregata showed a typically renantherous pattern. Quantitative differences in peroxidase bands reflect intra-section variation. Qualitative and quantitative variations in esterase patterns also provide useful taxonomic markers in the two sections. Chemical characters were also used in an investigation of the E. viminalis/E. dalrympleana complex in Tasmania. Macro-molecular characters of seedlings did not aid in distinguishing the two species, but differences in the phenolic compounds of the seedling leaves enabled positive identification of a \viminalis-type\" or a \"dalrympleana-type\" tree."