Betacyanin-forming callus of the red-flowering (var. JR) Portulaca grandiflora, Hook, is shown to contain dopamine, adrenaline, noradrenaline, and epinine. Whereas the synthesis of DOPA, dopamine, and betacyanin is much higher in callus kept in the dark than in illuminated callus, the other catecholamines are only accumulated in the dark. The synthesis of dopamine via DOPA can be demonstrated by the use of inhibitors.