Structure of Phloem

In this we will explain the structural and functional relationship of phloem and compare it with xylem. The location of phloem with respect to other tissues can be examined by a single transverse section, but to get an idea of their longitudinal route from stem to various branches requires a painstaking study of innumerable serial transverse sections along the height of the plant.

Figure: Branching, criss- crossing and remification of vascular bundles in a stem of clematis vitalba (schematic)

Figure shows a schematic drawing envisaged from serial sections. Note the branching, criss-crossing and ramification of vascular bundles. The longitudinal branching and fusion of phloem, particularly at the node show that phloem of one side of a stem can effectively cross over to the opposite side on its longitudinal path.