AP BIOLOGY

Detailed explanation-1: -Periderm = secondary tissue derived from the cork cambium (phellogen) and the cork cambium itself; replaces the epidermis in woody stems and roots (Liquidambar twig). It is usually a continuous ring (not always), all the way around the stem, root, or fruit.

Detailed explanation-2: -The periderm acts as the first line of defence for a plant, protecting wood and phloem from abiotic and biotic stresses. During secondary growth, through the increase in girth of plant organs, the periderm replaces the epidermis as the outermost tissue.

Detailed explanation-3: -The phellem, or cork, forms a series of cell layers at the outermost level of the periderm and is derived from the underlying meristematic phellogen layer (cork cambium).

Detailed explanation-4: -peri·derm ˈper-ə-ˌdərm. : an outer layer of tissue. especially : a cortical protective layer of many roots and stems that typically consists of phellem, phellogen, and phelloderm.

Detailed explanation-5: -cambium, called the phellogen or cork cambium, is the source of the periderm, a protective tissue that replaces the epidermis when the secondary growth displaces, and ultimately destroys, the epidermis of the primary plant body.