抄録
The differentiation of vascular elements in Zea mays roots proceeds centrifugally from late metaxylem, to early metaxylem, metaphloem, protophloem and protoxylem, but its maturation proceeds centripetally from protophloem to late metaxylem. The completion of vascular elements aparts 24-25 cm from root apex. The distances from root apex to the differentiation of vascular elements are shortened with root elongation, and Clowes'es generative centre does also. It depends upon the decrease of cell divisions in generative centre and differentiating zone.
