The leaf oils of the 10 Australian species of Medicosma have been examined. Medicosma cunninghamii produced an oil in which the principal components were the chromenes, evodionol and evodionol methyl ether, as well its the terpenes alpha-pinene, myrcene and (Z)-beta-ocimene. In M.. elliptica the major components were alpha-pinene (0.6-29%), sabinene (12-55%), myrcene (8-16%) and limonene (0.4-13%). Medicosma fareana produced an oil in which bicyclogermacrene (15-44%) was the principal component. M.glandulosa gave a variable oil in which alpha-pinene (t-35%) beta-caryophyllene (t-15%), aromadendrene (t-10%), (EE)-alpha-farnesene (1-13%), bicyclogermacrene (1-13%), globulol (1 -8%) and spathulenol (3-1 0%),were the principal contributors, while for M. obovala, u-pinei ie (1-12%), limoi iel ie ( 1013%). (E)-beta-ocimene (14-23%), beta-caryophyllene (17-19%) and alpha-humulene (6-14%) were the major components. Medicosma riparia produced a leaf oil that was evenly distributed between sesquiterpenes and aromatic components, the principal components being alpha-selinene (7-15%), and the two chromenes, evodionol (1-3%) and evoclionol methyl ether (30-56%). Medicosma sessiliflora presented an almost completely sesquiterpenic oil with beta-caryophyllene (3-11%). aromadendrene (5-14%), humulene (8-19%), and spathulenol (3-12%) as major components. The leaf oil of Medicosma sp. (East Mulgrave River R.L. jago+ 3696) presented a sesquiterpenic oil in which the principal component was bicyclogermacrene (17-21%). Medicosma sp. (Karnak P.I.. Forster+ PIF15541) produced a variable oil in which one sample contained 50% monoterpenes while the remainder were more heavily sesquiterpenic. The major compountds detected were alpha-pinene(1-40%), bicyclogermacrene (3-8%) and spathulenol (10-22%). The oil of Medicosma sp. (Mt Mellum P.I. Forster+ PIF25572) was dominated by alpha-pinene (38-54%) which -,vas accompanied by lesser amounts of (Z)(Z>-beta-ocimene (10-13%). Oil yields, with the exception of M. obovata, which were 1-2%, were low, being in the range 0.04-0.5% based on fresh leaves. None of the oils would appear to have an economic potential.
