DENDROLOGY

Detailed explanation-1: -C: The cambium cell layer is the growing part of the trunk. It annually produces new bark and new wood in response to hormones that pass down through the phloem with food from the leaves.

Detailed explanation-2: -Various kinds of cell layers that constitute the bark are – Periderm (phellogen, phellem and phelloderm), primary cortex, pericycle, primary and secondary phloem. These all tissues are present outside the vascular cambium.

Detailed explanation-3: -The inner soft bark, or bast, is produced by the vascular cambium; it consists of secondary phloem tissue whose innermost layer conveys food from the leaves to the rest of the plant. The outer bark, which is mostly dead tissue, is the product of the cork cambium (phellogen).