A NUMBER of edible green plant tissues have been successfully cultured on synthetic media in tissue culture. The amount of growth and degree of differentiation varied with the composition of the medium and other environmental conditions. Growth and chlorophyll development of some cultures were correlated with the type and amount of sugar in the medium1. Iron holds a key position in intact plants in the biosynthesis of chlorophyll and, therefore, comparisons of iron sources for growth and chlorophyll formation in isolated tissues were also recently examined2. This communication describes effects of several iron sources and of a pancreatic digest of lactalbumin (`Edamin') on the growth and chlorophyll content of several species of callus tissue.