Torus is composed of suberin. Torus is the thickened part of a stem, the receptacle, from which the flower and fruit parts grow. Torus, a structure of the xylem. Suberin is highly hydrophobic and a somewhat rubbery material. Its main function is to prevent water from penetrating the tissue. In roots, suberin is deposited in the radial and transverse cell walls of the endodermal cells.