The Generation and Elaboration of Primary Vascular Tissue Patterns in Roots of Zea

Files of metaxylem were traced to their levels of origin in the root apex of Zea. The first four files differentiated simultaneously, with new files added sequentially at more proximal levels in the root. The differentiation of the metaxylem was correlated with dimensions of the quiescent center. From these correlations a hypothesis is advanced of the possible regulatory effects of the quiescent center on primary vascular tissue patterns in roots.