The leaf oils of the two Australian species of Decaspermum have been examined by GC and GC/MS. The leaf oil of D. struckoilicum contained alpha-pinene (37.5%) as its principal component in an oil that contained similar amounts of mono- and sesquiterpenes. The major sesquiterpenes identified in the oil were beta-caryophyllene (2.4%), alpha-humulene (2.2%) and alpha- and beta-eudesmol (8.2% and 8.1%, respectively). Decaspermum humile produced a leaf oil that contained either approximately equal amounts of mono- and sesquiterpenes or had a majority of the latter components. The principal monoterpenes were alpha-thujene (0.1-13%) and alpha-pinene (0.2-21%). Other prominent monoterpenes identified were limonene (0.2-8%), myrcene (0.3-10%), beta-phellandrene (0.1-5%), linalool (0.3-9%) and terpinen-4-ol (0.3-6%). 1,8-Cineole was usually absent from the oils. The main sesquiterpenes identified in the oils were beta-caryophyllene (0.7-5%), aromadendrene (1-6%), viridiflorene (1-7%), delta-cadinene (0.4-14%), bicyclogermacrene (0.2-10%), globulol (1-9%) and in some collections 7-epi-alpha-selinene (trace-9%).
