OBSOLETEC 3.1 metaxylem differentiation of root. true plant_structure_development_stage metaxylem differentiation of lateral root (related) PO:0007521 metaxylem differentiation of primary root (related) metaxylem differentiation of crown root (related) OBSOLETE. Differentiation begins with the enlargement and vacuolation of the tracheary elements of the metaxylem. These stages are based on Arabidopsis plant. This term has been obsoleted to keep the structure simple.