Studies on the origin and structure of the nodal plexus of rice seedling

Abstract

With serial sections made by micorotome, the nodal plexus of rice seedlings have been investigated about their origin and connection with other vascular bundles. (1) In the transverse sections, it is observed that the nodal plexus developed a fairly good forms, the imperfect concentric vascular bundles surrounding the phloem. In longitudial sections, therefore, the nodal plexus is been like a form that accompanied with the xylem on one side or both side of the phloem. (2) It seems that when the peripheral vascular bundles begin to grow, the cells, surrounding the vertical bundles in the state of the procambium, begin the differentiation and develope into the nodal plexus, (3) In the case the nodal plexus has grown fully, in the node of the lower part, they form a network in the pith and they are connected with peripheral vascular bundles as well as together with the combined vascular bundles. The nodal plexus are not connected with the vertical bundles. But the vertical bundles which streched down from the leaf located at the 3rd node above are connected with the nodal plexus for the first time. The connection of the nodal plexus with the root and the tillers is not fundamental.