Vascular Transfer Cells in the Vegetative Nodes of Wheat

Abstract

The structure of the vascular bundles in the vegetative nodes and in the terminal "node" of the culm of wheat has been studied in serial transverse sections. Three types of bundles are present in the vegetative nodes (except for the terminal node): (1) nodal plate bundles, which contain numerous phloem transfer cells but no xylem transfer cells; (2) large elliptical bundles containing numerous xylem transfer cells; and (3) diffuse bundles, which alternate with the elliptical bundles, lack xylem transfer cells, but contain phloem transfer cells especially where they join with the nodal plate bundles. The significance of the presence of xylem transfer cells in the stem nodes and their absence from the terminal node of the culm and the internodes, and the possible function of the phloem transfer cells, are discussed.