Definition
• Barks may be defined as those drugs formed of
tissues outside the vascular cambium, which is
the place where the separation takes place,
because the cells are young, very soft and
ruptured. • They may be obtained from stems branches and
roots of woody plants. • The cambium formed of delicate meristematic
tissue responsible for reproduction of new
conducting vascular tissues. 1
elopment • The changes by which the bark is developed from
the tissues of the young stem are brought by the
activity of two circles of meristimatic cells;
A. Inner circle or cambium which produces wood
towards the interior and bast towards exterior.
B. outer circle or phellogen which produces Cork
towards the exterior and phelloderm towards
the interior.