Cell  division  in the vascular
   cambium.
a. Types of cell division.
A  cambium cell can divide transversely to form more cambium cells
(C) or radially to produce either xylem (X) or phloem (P) cells.
<lI> Accumulation of secondary growth.
Repeated radial divisions build up layers of xylem and phloem. The
cambium usually produces much more xylem than phloem.