Manuka oil is produced in New Zealand by steam distillation of the fresh leaves and small branches of Leptospermum scoparium J. R. Forst et F. Forst collected from the wild. Leptospermum scoparium is known to exist in at least three varietal forms such as L. scoparium J. R. Forst et G. Forst var. rotundifolium Maiden et Betche, L. scoparium var. scoparium and L. scoparium var. eximium J. R. Forst et G. Forst. The three varieties of L. scoparium can be found in Australia.
In 1979, Flynn et al. reported that L. scoparium var. rotundifolium contained the following constituents:
Twenty years later, Brophy et al. (1999) examined the oil composition of the other two varieties of L. scoparium. The composition of these oils is shown in Table I.
As can be seen, the varietal oils of L. scoparium of Australian origin do not possess the typical manuka triketone oil composition as was originally reported by Briggs et al. (1938 and 1945).