Earlier work with buckwheat seedlings showed that dihydrokaempferol (3,5,7,4′-tetrahydroxyflavanone) (1) is a good precursor for cyanidin and quercetin. Since cell suspension cultures have several advantages for the quantitative comparison of the incorporation of a radioactive precursor into a product, the role of 1 in the biosynthesis of cyanidin was reinvestigated with cell cultures of Haplopappus gracilis. These cultures show good production of cyanidin-glycosides in blue light in a medium containing sucrose, 2,4-D and Fe-EDTA. Maximum anthocyanin production and maximal activity of phenylalanine ammonia-lyase is reached about 60 — 70 hrs. after the onset of illumination. The incorporation of 1 and of phenylalanine and 4,2′,4′,6′-tetrahydroxychalcone into cyanidin was compared under identical conditions after 1, 3 and 6 hrs. feeding time. 1 prooved to be by far the best precursor for cyanidin. The feeding time required was much shorter and the incorporation rates were much higher than in experiments with seedlings.