Detailed GC and GC-MS analyses of oil of Melaleuca have identified several constituents not previously reported from Melaleuca alternifolia and clarified some earlier assignments. The range, mean, and coefficient of variation for the principle constituents in 800 typical samples are presented along with the compositions of several substandard oils. Isolation and storage procedures affecting the chemical composition of the oil are reported. Ethanolic extraction of mature leaves gave solutions suitable for direct injection into a gas chromatograph for the qualitative determination of tea tree oil. Comparison with conventional steam distillation showed that this technique was suitable for preliminary analysis of tea tree oil yield and quality.The essential oil of Melaleuca alternifolia Cheel (family Myrtaceae) was first reported early this century (Penfold, 1925) from the leaves of a paperbark tea tree growing in the central coastal region of eastern Australia. This taxon, previously known as Melaleuca linariifolia var. alternifolia, had been raised to species rank the previous year (Cheel, 1924), and the entire genus is at present undergoing taxonomic revision (Barlow, 1987, personal communication).Possible economic uses of the oil were immediately investigated as affinities with nutmeg oil were noted (Penfold, 1925; Penfold and Morrison, 1946) and high bactericidal activity was recorded (Penfold and Grant, 1925). Early reports list many medical conditions responding to treatment with oil of M. alternifolia (Penfold and Morrison, 1946;Guenther, 1950;Lassak and McCarthy, 1983).The oil was also used in machine "cutting" oils, as a perfumery toner and blender, and as a flavoring and antiseptic agent in denture and mouth washes (Guenther, 1950;Pickering, 1956). Consequently, the oil has maintained a place in the essential oil trade and has subsequently been investigated for use as a nutmeg flavor substitute (Pickering, 1956), in the treatment of furunculosis (Feinblatt, 1960), in combatting wood-destroying fungi (Maruzzella et al., 1960), in treatment of vaginitis (Pena, 1962), as an antiseptic in a "Water-Jel" fire blanket (Water-Jel, 1973), in veterinary products (Lassak and McCarthy, 1983), and as an additive to podophyllotoxin in oral contraceptives (Davis, 1984). An issue of Phytotherapy was dedicated principally to the medicinal uses of M. alternifolia oil (Belaiche, 1985; Carnero, 1985). Numerous studies have established the bactericidal and fungicidal efficacy of the oil against Bacillus typhosus, Staphylococcus aureus,

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Phenotypic variation in heartwood and essential-oil characters of Santalum austrocaledonicum was assessed across eleven populations on seven islands of Vanuatu. Trees differed significantly in their percentage heartwood cross-sectional area and this varied independently of stem diameter. The concentrations of the four major essential-oil constituents (alpha-santalol, beta-santalol, (Z)-beta-curcumen-12-ol, and cis-nuciferol) of alcohol-extracted heartwood exhibited at least tenfold and continuous tree-to-tree variation. Commercially important components alpha- and beta-santalol found in individual trees ranged from 0.8-47% and 0-24.1%, respectively, across all populations, and significant (P<0.05) differences for each were found between individual populations. The Erromango population was unique in that the mean concentrations of its monocyclic ((Z)-beta-curcumen-12-ol and cis-nuciferol) sesquiterpenes exceeded those of its bi- and tricyclic (alpha- and beta-santalol) sesquiterpenes. Heartwood colour varied between trees and spanned 65 colour categories, but no identifiable relationships were found between heartwood colour and alpha- and beta-santalol, although a weak relationship was evident between colour saturation and total oil concentration. These results indicate that the heartwood colour is not a reliable predictive trait for oil quality. The results of this study highlight the knowledge gaps in fundamental understanding of heartwood biology in Santalum genus. The intraspecific variation in heartwood cross-sectional area, oil concentration, and oil quality traits is of considerable importance to the domestication of sandalwood and present opportunities for the development of highly superior S. austrocaledonicum cultivars that conform to the industry's International Standards used for S. album.