The morphogenic pathway of adventitious bud and shoot regeneration at the ends of Troyer citrange epicotyl cuttings is determined by polarity and explant orientation. In explants planted vertically with the basal end inserted in the medium, bud formation at the apical end occurs by direct organogenesis. Bud growth and subsequent shoot formation is markedly increased by the addition of 6-benzyladenine (BA) to the medium. This growth regulator also increases the number of buds formed. When they come into contact with the culture medium, both the apical end and the basal end of the cuttings form a vigorous callus with many xyllary elements, more numerous in the calli from the basal end. In these calli, buds differentiate by a process of indirect organogenesis. This indirect regeneration pathway requires the addition of 6-benzyladenine to the medium, and the number of buds formed is higher at the apical end than at the basal end of the cuttings. This pathway of regeneration is reduced as the position of the cuttings during incubation deviates from the normal upright vertical position. Thus, for the basal end of the cuttings, the number of buds and shoots formed is higher when the explants are placed vertically than when they lie on the surface of the medium. For the apical end, this number is higher in explants placed horizontally than when inserted vertically in the medium in an inverted position.