Samples of M. ericifolia leaves were obtained from 19 locations as follows: DL3104- 3110, Coopernook, New South Wales (NSW), 31° 49′ 31″ S, 152° 36′ 48″ E (Site No. 1); DL3114-3120, Hawks Nest, NSW, 32° 40′ 09″ S, 152° 10′ 12″ E (Site No. 2); DL3240-3244, Hexham, NSW, 32° 48′ 50″ S, 151° 42′ E (Site No. 3); DL3245-3249, The Entrance, NSW, 32° 22′ 24″ S, 151° 28′ 19″ E (Site No. 4); DL3397-3401, Tuggerah Lake, NSW, 33° 21′ S, 151° 27′ E (Site No. 5); DL3250-3254, Georges River, NSW, 33° 58′ 42″ S, 151° 00′ 14″ E (Site No. 6); DL3255-3259, Berry, NSW, 34° 46′ 37″ S, 150° 45′ 27″ E (Site No. 7); DL3260-3264, Lake Durras, NSW, 35° 36′ 00″ S, 150° 16′ 17″ E (Site No. 8); DL3265- 3269, Wallaga Lake, NSW, 36° 23′ 43″ S, 150° 03′ 04″ E (Site No. 9); DL3270-3274, Wallagoot, NSW, 36° 44′ 50″ S, 149° 55′ 46″ E (Site No. 10); DL3275-3279, Genoa, Victoria (Vic), 37° 25′ 56″ S, 149° 38′ 41″ E (Site No. 11); BVG3024- 3028, West of Lakes Entrance, Vic, 37° 48′ S, 148° 03′E (Site No. 12); BVG3014-3018, West of Lang Lang, Vic, 38° 13′ S, 145° 30′ 13″ E (Site No. 13); BVG3019-3023, East of Welshpool, Vic, 38° 38′ 28″ S, 146° 30′53″ E (Site No. 14); ACC1019/1-2, 5-7, Nelson on the Glenelg River, Vic, 38° 03′ S, 141° 00′ E (Site No. 15); KJ1-5, Airport Flinders Island, Tasmania (Tas), 40° 05′ S, 148° 00′ E (Site No. 16); KJ6-10, Lackrana Road Flinders Island, Tas, 40° 18′ S, 148° 06′ E (Site No. 17); ACR1848/1-3, Woolnorth Point, Tas, 40° 38′ 30″ S, 144° 43′ 30″ E (Site No. 18); JB4509, Robins Island Track, Tas, 40° 45′ S, 144°53′E (Site No. 19). The majority of samples were collected during June to December 1999 with the exceptions being sites 5, 15 and 18, which were collected during July to October 2000. Leaf material totaling about 100 g of fresh leaves and twigs was obtained mainly from five widely spaced individual trees per location.

Oil composition varied quantitatively throughout the species range rather than qualitatively in an apparent association with latitude of occurrence. Linalool and linalool oxide were abundant in the oils from the north of the species range in New South Wales with a gradual southerly decline in these compounds to central Victoria with concomitant increase in the proportions of 1,8-cineole, alpha-terpineol and limonene. The most southerly populations sampled in southern Victoria and Tasmania gave oils containing relatively high proportions of 1,8-cineole (mean 34.5%) and low proportions of linalool (3%). Four populations from the Central Coast of NSW (Coopernook, Hawks Nest, The Entrance and Tuggerah Lake) provided the greatest opportunity of identifying seed trees that combine the attributes required for plantation development. The tree that had the best combination of oil traits (DL 3116 from Hawks Nest) had an oil yield of 4.5%, a linalool content of 60% and a 1,8-cineole content of 16%.

One hundred grams of mature leaves were collected from 2 to 10 widely spaced trees per site and sent to Sydney for analysis as soon as possible after collection. Samples usually arrived in the laboratory within 48 h of collection. The majority of the sampling was done between December 1998 and October 1999. Seasonal trends in oil yields and composition are confounded in the data on geographic variation, but these were considered minor in the context of this study.

Chemotype 1 is comprised of E-nerolidol (74-95%) and linalool (14-30%) and is found from Sydney, north along the east coast of Australia to Selection Flat, New South Wales, with an isolated occurrence near Maryborough, Queensland. Two divisions occur in this chemotype which are based on the presence or absence of significant proportions of linalool (14-40%). Chemotype 2 contains 1,8-cineole (10-75%), viridiflorol (13-66%), alpha-terpineol (0.5-14%) and beta-caryophyllene (0.5-28%) in varying proportions and order of dominance in the oils. It is found throughout the distribution of the species, from Sydney to Papua New Guinea and New Caledonia. Within chemotype 2 there appears to be a continuous spread of oil composition without formation of any further discrete divisions as in chemotype 1. Analyses have shown that M. quinquenervia trees that occur at latitudes south of 25d S have high oil yields (1-3% w/w%, fresh leaves) and comprise chemotypes 1 and 2. North of 25d S, however, chemotype 1 does not occur and oil yields amongst the Australian populations are uniformly low (0.1-0.2%).