lemon oils are amongst the highest volume and most frequently traded of the flavour and fragrance essential oils. citronellal and citral are considered the key components responsible for the lemon note with citral (neral + geranial) preferred. of the myriad of sources of citral, the australian myrtaceous tree, backhousia citriodora, is considered superior. this review examines the history, natural occurrence, the cultivation, the taxonomy, the chemistry, the biological activity, the toxicology, standardisation and the commercialisation of backhousia citriodora especially in relation to its essential oil.