Extensive research has focused on the concentration of aglycones within brown boronia (Boronia megastigma) ¯owers, however emission of volatiles into the headspace above these ¯owers is not well documented. Using solidphase microextraction (SPME) to trap volatiles and GCMS analysis, we observed 23 volatiles in the headspace above buds and ¯owers throughout ¯ower maturation, above dissected ¯oral organs and above whole plants held for 36 h under either continuous light, continuous dark or 12 h light: 12 h dark: 12 h light treatments. Fully-opened ¯owers emitted the most complex mixture of volatiles and in the greatest quantity, with a rapid decline in senescent ¯owers. Caryophyllene, humulene and bicyclogermacrene declined as ¯ower buds matured; b-ionone increased. From the individual ¯oral organs, emission from the petaline anthers comprised 38 % of total emissions from the (calculated) whole ¯ower', with 27 % contributed by the petals and 10.5% by the stigma. Monoterpenes dominated the headspace from the calyx; dodecyl acetate, methyl jasmonate and (Z)-n-heptadec-8-ene were relatively predominant in emissions from the androecium. b-Ionone, the major ¯oral volatile in brown boronia, dominated volatiles emitted from the stigma (87 %). However, the relatively tiny petaline anthers, active in pollen production and high in carotenoids, contributed the greatest overall amount of b-ionone to emission from the whole ¯ower. There were three dierent patterns in emission of volatiles from plants in response to dierent light conditions: (1) emission patterns identical irrespective of light environment, with maximum emission in theendogenous' dark period, i.e. when the plant would normally have been in the dark (a-pinene); (2) similar emission in all treatments, with an increase and decline over a period of 26 h (5-acetoxy linalool, cyclic b-ionone, dodecyl acetate and (Z)-n-heptadec-8-ene); and (3) emission in all treatments but enhanced in the dark, with a 27.5 h period in some cases (cyclic b-ionone endoperoxide, dihydro b-ionone, b-ionone, and `total volatiles'). Preliminary evidence is presented for endogenous control of emission of a number of volatiles such as a-pinene, with perhaps diurnal control of others such as b-ionone.