Primary and secondary growth.
<P>
<Li> Apical  meristem initiates primary growth, producing primary xylem
and primary phloem, as well as the vascular cambium.
<Li> Secondary  growth  occurs  at  the  vascular  cambium, which forms
secondary xylem (wood) and secondary phloem (inner bark).
<Li> The cork cambium produces cork (outer bark).