A preliminary survey of selected species of endemic plants to determine commercial cropping potential for essential oils

This work was embarked upon as a preliminary survey of the Tasmanian endemic essential-oil-bearing plants, with a view to locating species which may be suitable for commercial production of oil. Initially, twenty plant species were selected as having been observed to contain an essential oil. The species were : Bedfordia salicina, Beyeria viscosa, Callitris tasmanica, Cassinia aculeata, Drimys lanceolata (also known as Tasmannia lanceolata), Eriostemon virgatus, Kunzea ambigua, Leptospermum glaucescens, Leptospermum lanigerum, Leptospermum scoparium, Melaleuca squamea, Melaleuca squarrosa, Olearia argophylla, Olearia phlogopappa, Phebalium squameum, Prostanthera lasianthos, Senecia linearifolius and Zieria arborescens. Material from these species was taken for steam distillation and solvent extraction, and the oil samples, thus obtained, were analysed by GC-MS. In addition, data on yields of oil were compiled, in order that comparisons between species could be made. The number of species under investigation was reduced to ten, by excluding those that did not possess a persistent or powerfully pleasant odour. The other major criterion used in determining which species may be of commercial value was oil yield, which was not to be less than 0.1%. The species that were retained were as follows: B. viscosa, C. tasmanica, D. lanceolata, E. virgatus, E. amygdalina, K. ambigua, L. glaucescens, L. lanigerum, 0. phlogopappa and P. squameum. Comparisons between the estimated yield of these species, on a per hectare basis, with that of commercial essential oil crops, showed that they have the potential to produce similar quantities of oil. Scanning electron microscope studies of the oil glands of the ten selected species were undertaken. These showed definite similarities in structure, both among themselves and with glands described in the literature. Small-scale propagation trials were run with the species listed above. Many were found to grow readily form cuttings, whilst others were easily raised from seed, and all of the ten species were propagated by one or other of these means. However, tissue culture techniques would vastly improve the efficiency of any large scale propagation project. The GC-MS results showed the preesence of many commercially important compounds, as well as one which had not been cited previously in the literature, namely epi-Y-eudesmol in Olearia spp. Compounds which were identified by this method were quantified by determining the area under the relevant peak. In addition, the oils from these species were examined using a gas chromatograph which had been equipped with a splitter, so that the various components could be described as they were vented from the column.