This study investigated the cyanogenic constituents of Rawsonia lucida (Flacourtiaceae). Dried leaves liberated 5.6 μmol HCN/g. The cyanogenic glycoside gynocardin (1) was isolated via boiling MeOH extraction, silica gel fractionation, and MPLC purification, with its identity confirmed by 300 MHz ¹H and 75 MHz ¹³C NMR spectra (and comparison with authentic gynocardin and its hexaacetate). Additionally, the possible biosynthetic precursor (2S,1'R)-2-(2'-cyclopentenyl)glycine (2) was detected through water extraction, Dowex-50W (H⁺) ion exchange chromatography, and 400 MHz ¹H NMR analysis. Chemotaxonomically, the presence of gynocardin suggests a close relationship between Rawsonia and Pangieae/Oncobeae s. str., making R. lucida the first member of Erythrospermeae sensu Lemke with identified cyanogenic constituents.