In the primary structure of root, the primary xylem is diarch and the development of both the primary xylem and the primary phloem is exarch.
In the primary structure of root, the primary xylem is diarch and the development of both the primary xylem and the primary phloem is exarch.
在根的初生结构中，其初生木质部为二原型，木质部及韧皮部的发育均为外始式。