The crystal structures of two triclinic polymorphs of the previously unreported flavonoid 3´,5-dihydroxy-3,4´ dimethoxy-7-(3-methylbut-2-enyloxy)flavone, from the indigenous Australian tree Melicope elleryana, have shown two largely differing conformational forms; one with an extended, the other a convoluted C7 substituent side chain. In both forms, intermolecular head-to-tail hydrogen-bonding associations give simple chain-polymer structures.