Influence of growth regulators during initiation ofMimosa tenuiflora calli tissue varied according to explant source. KN (Kinetin) affected hypocotyls, while an interaction between different combinations of 2,41) (2,4 dichlorophenoxyacetic acid) and KN induced cotyledons,stems and leaves. Calli growth after 60 days was influenced by both hormones in cotyledons, by 2,4D in hypocotils and by an interaction of the two regulators in stems and leaves. The indole alkaloid Nb-Nb dimethyltryptamine was found to be present in some cultures at a level comparable to that of the source plant.