Vascular anatomy of fabaceous nodules of determinate growth

The vascular anatomy of nodules of 12 genera of tropical pasture and grain legumes of three tribes of the Fabaceae is described. Tracheary strands branch dichotomously and repeatedly from a root connection and generally terminate within sealed pockets of endodermis. Anastomosis of vascular strands at the nodule tip to form a complete xylem circuit was seen in three genera (Vigna, Glycine and Lablab). The functional significance of vascular structure is discussed in terms of pathways of solute movement between the infected cells and the root, and the permeability of the nodule cortex to gases.