The lower leaves of fern Notholaena sulphurea contain a new flavonoid called 2,3-trans-5,2'-dihydroxy-7,8-dimethoxy-dihydroflavonol-3-O-acetate, along with a co-constituent called 2,3-cis diastereoisomer. This acylated flavonoid is unique to N. sulphurea and confirms the fern's classification within the Notholaena genus. The discovery of this novel compound may have implications for future studies on the chemical makeup and potential medicinal properties of ferns.