A CELEBRATION OF THE HISTORY, CULTURE, SCIENCE AND TECHNOLOGY OF RECHERCHE BAY
CSIRO Marine and Atmospheric Research Auditorium Hobart, Tasmania
26–28 February 2007

Eucalypt taxonomy – from L’Héritier to DNA
Professor Pauline Ladiges, FAA

Pauline Ladiges is the Head of the School of Botany at the University of Melbourne. She has a wide interest in the diversity and evolution of the Australian flora and is best known for her research work on the phylogeny and biogeography of the eucalypts. She has published more than 120 scientific papers, is an elected Fellow of the Australian Academy of Science, and recipient of the Royal Society of Victoria's Research Medal for 2005. She has co-authored and co-edited three award-winning biology textbooks for Australian secondary and tertiary education.

The eucalypts are the single group of plants that are universally associated with Australia. Although the first botanical collections of eucalypt species was made by Joseph Banks and Daniel Solander at Botany Bay in 1770, it was in 1777, on Cook's third voyage, that David Nelson collected a specimen from Bruny island, Tasmania. This specimen was taken back to the Natural History Museum in London and formally named Eucalyptus obliqua by the French botanist L’Héritier. This is the type specimen for the genus Eucalyptus, the name meaning 'well (eu) covered (calyptos)', referring to the distinctive cap that covers the young flowers of most eucalypt species.

Since the time of the early collectors, more than 700 species of eucalypts have been named, with more than 500 in the genus Eucalyptus the remainder being placed in the bloodwood genus, Corymbia, and the small genus Angophora. Four relictual rainforest genera that occur in northern Australia, New Guinea or New Caledonia (Allosyncarpia, Stockwellia, Eucalyptopsis and Arillastrum) are now recognised as their closest relatives. Discovery of the phylogenetic relationships (evolutionary tree) of the eucalypt group has been based on combining studies of morphological characters with molecular data. DNA comparisons have identified major lines of evolution that date back to 70 million years ago. The biogeographic patterns suggested by these phylogenies can be interpreted in the light of past climatic and geological changes.