AbstractCalystegines are a new group of polyhydroxy nortropane alkaloids that have recently been isolated fromCalystegia sepium.Thin layer chromatography systems have been developed for preliminary screening for these compounds, whilst quantitative analysis has been achieved, following silylation, by gas chromatography (GC) with an internal standard. The reproducibility and accuracy of the quantification method have been examined. The identity of the calystegines was assessed by co‐chromatography with reference samples, by chemical ionization mass spectroscopy (CI‐MS) of isolated calystegines, and by GC‐MS. Cultured roots ofAtropa belladonnawere examined for calyste