VARIATION IN CALLISTEMON VIMINALIS (MYRTACEAE) - NEW EVIDENCE FROM LEAF ESSENTIAL OILS

Analysis of leaf essential oils in Callistemon viminalis (Sol. ex Gaer tner) G.Don ex Loudon was used to determine the validity of infraspeci fic taxa recognised in the taxon. The leaf essential oils obtained, in 0.08-0.63% yield, have been found to be qualitatively similar over th e wide geographic distribution of the species (from 12 degrees 28' S t o 29 degrees 43' S) but to differ quantitatively over this range. All oils contained alpha-pinene, beta-pinene, myrcene and 1,8-cineole as t heir major compounds and traces of the beta-triketones, leptospermone and flavesone. Overall the essential oils that contained the most 1,8- cineole (60-82%) came from the more southern latitudes (29 degrees 14' S to 20 degrees 16' S) while those oils with less 1,8-cineole (0.5-47 %) came from the more northerly latitudes (12 degrees 53' S to 25 degr ees 18' S). There was overlap in the region 25 degrees S to 22 degrees S, although the majority of samples from this region contained high 1 ,8-cineole values. Partial least squares analysis allowed the latitude to be calibrated by the leaf oil concentrations. These data would len d only equivocal support for the establishment of two intraspecific ta xa of C. viminalis.