Annular thickening Rings of thickening laid down on the inner wall of protoxylem vessels and tracheids.环状加厚：原生木质部导管和管胞的内层环状増厚。
In diarch and tetrarch roots the primodia of the lateral root can be initiated from the pericycle situated opposite adja在原型和原型的根中,发现侧根正对着原生木质部的位置,也有在原生木质部和原生韧皮部之间的部位,由中柱鞘细胞脱分化再分化而成。