Introduction

The Australian flora is rich in trees and shrubs from the family Myrtaceae. Eucalyptus, is well known for profuse oil glands which contain a diverse range of constituents, of which 1,8-cineole is the most abundant and most commercially utilized (Doran 1991). The genus Melaleuca also contains hundreds of individual species with a myriad of oil constituents present in the leaf (Brophy and Doran 1996). Both genera extend beyond Australia to neighbouring regions of SE Asia and the Pacific. Eucalyptus is now grown extensively in many parts of the world. Consequently Australia produces only about five percent of the world’s eucalyptus oil. Although Melaleuca has not yet been as extensively dispersed, plantings of M. alternifolia have been established in the United States, Zimbabwe, New Zealand, China, India and other countries. Provenances of M. quinquenervia, a species native to Australia, New Caledonia and Papua New Guinea, have been grown in Madagascar (Ramanoelina et al. 1992, 1994) and, along with the New Caledonian provenance, have been used as a source of niaouli oil. M. cajuputi, native to Australia, Indonesia, Papua New Guinea, Malaysia, Thailand, Cambodia and Vietnam, along with some provenances of M. quinquenervia have sometimes been described as M. leucadendron (Todorova and Ognyanov 1988; Motl et al. 1990). In addition, M. quinquenervia is grown elsewhere as an ornamental species and for swamp reclamation and erosion control. In Florida this species has colonized vast areas to the detriment of the environmentally important Everglades (Weiss 1997) but in Hawaii, plantings of an estimated two million trees have not produced a weed problem (Geary 1988).