Cyanogenic glycosides are secondary plant compounds that occur widely in the plant kingdom. They are the source of HCN which can render the plant toxic if it is taken as food. The enzymes responsible for production of the HCN have long been known. More recent biosynthetic studies have established certain protein amino acids as precursors of the aglycones, and indicate N-hydroxyamino acids, aldoximes, nitriles and alpha-hydroxynitriles as intermediates. In sorghum the several biosynthetic enzymes catalyzing the flow of carbon atoms from L-tyrosine through such nitrogenous intermediates are located in a membrane fraction and may be capable of metabolic channeling.