Feeding experiments using 13C labelled precursors and NMR spectroscopic studies revealed general biosynthetic incorporation of phenylalanine and variable incorporation of cinnamic acid, p-coumaric acid, caffeic acid and ferulic acid into phenylphenalenones in root cultures of Anigozanthos preissii. Evidence was obtained for parallel pathways of phenylphenalenone biosynthesis, with respect to the left phenylpropanoid unit, and a sequence involving utilisation of p-coumaric acid with late generation of an intermediate catechol moiety in the right phenylpropanoid unit.