Some studies were undertaken to identify the association of distribution pattern of photosynthetic assimilates with the phyllotaxis and vascular system in tomato plants. The vascular system of tomato consisted basically of four orthostichies with two vascular bundles from each leaf. It was clearly observed that the arrangement of the vascular system affected a distribution pattern of ¹⁴C-assimilates. The source leaves exported only a smaller portion of their assimilates to young leaves located on the opposite orthostichy to them, as compared with those on the same as well as side orthostichies. Since tomato plants have a sympodial branching system, the leaf which was situated just above the inflorescence differentiated in advance to the inflorescence. The vascular bundles of the leaf in a sympodial branch near inflorescence developed in the location between the inflorescence and the leaf just above it. This vascular pattern cause a limited distribution of photosynthetic assimilates to the inflorescence from the leaf just above it.