Botanic Gardens Trust, Sydney, Australia


Research Visit to New Caledonia

Royal Botanic Gardens and Domain Trust scientists have a long history of interest and research activity in New Caledonia, in various plant groups ranging from bryophytes to flowering plants from families such as Rutaceae and Proteaceae. During the past year Peter Wilson has had an active involvement in research on the distinctive genus Xanthostemon in the family Myrtaceae, which is a prominent feature of the ‘maquis’ vegetation of New Caledonia.

The genus Xanthostemon has a wide distribution and occurs in northern Australia, New Caledonia, New Guinea, the Solomon Islands, the Philippines and parts of eastern Indonesia. Peter has had a long-term interest in the genus and its close relatives, dating back to his PhD in the late 70s. He has published on the taxonomy of the group a number of times but this time the opportunity arose to do some DNA-based research, which would potentially answer a number of questions about the biogeography and evolution of the genus. In New Caledonia, Xanthostemon is particularly species-rich. There are 19 accepted species in this genus and there are a few others in the small, related genera Purpureostemon (one species) and Pleurocalyptus (two species).

The current project was initiated by Dr Adrien Wulff of the University of New Caledonia and the Institut Agronomique néo-Calédonien (IAC) and involved a coursework Masters student, Olivier Laporte-Daube, doing a six month research project. Towards the end of the six months of the student’s work, in late August to early September 2012, Peter was able to visit New Caledonia, with the airfare provided by the IAC. During his time there, he gave a lunchtime lecture on Myrtaceae at the university and worked with both Adrien and Olivier on aspects of the project. Adrien and Peter reviewed the herbarium vouchers and some issues relating to hybridisation were discussed. We both went over the preliminary DNA sequence data with Olivier to assist him with writing up his project report.

Peter was also able to participate in a number of short field trips that enabled him to see some of the amazing vegetation of the island, including some of the species being studied. Near Koauoua, on the eastern side of the island, he saw two species of Xanthostemon (see photo of X. macrophyllus) and a few days later, on a nickel mining area at Tiebaghi, in the far north of the island, he found numerous plants of the striking red-flowered Purpureostemon ciliatus (see photo).

This work is continuing in the Trust’s DNA lab, where Peter and his colleagues are expanding the non-New Caledonian coverage of the genus to broaden the understanding of its relationships and the evolution of the morphological characters that have traditionally been considered important.


X. macrophyllus

Purpureostemon ciliatus