(i) Due to more activity of certain portions of phellogen,
the phellem cells are cut off very rapidly and hence,
these cells are loosely arranged with a lot of
intercellular spaces.
These loosely arranged cells are called
complementary cells and loosely arranged areas in
the periderm are called lenticels.
(ii) The number of lenticels formed in a stem is variable.
(iii) Lenticels help in
(a) gas exchange.
(b) lenticular transpiration.