Derivatives of the secondary meristem in the steler region are
Phellem and phelloderm
Alburnum and primary phloem
Duramen and alburnum
Primary xylem and secondary phloem
The common bottle cork is a product of
Velamen is needed for
Passage cells are found in
The tunica-corpus theory was proposed by
Amphiphloic $(bicollateral)$ condition of stele means that