Q.In the diagram of lenticel identify the parts marked as A,B,C,D
a. A. phellem, B. Complementary tissue, C. Phelloderm, D. Phellogen.
b. A. Complementary tissue, B. Phellem, C. Phellogen, D. Phelloderm.
c. A. Phellogen, B. Phellem, C. Phelloderm, D. complementary tissue
d. A. Phelloderm, B. Phellem, C. Complementary tissue, D. Phellogen

Step 1. Locate the raised mound (B). The pore of the lenticel is filled by a mass of loosely arranged, rounded, thin-walled cells with intercellular spaces that bulges outward through the ruptured epidermis. This loose filling tissue is the complementary cells (complementary tissue), produced continuously by the phellogen beneath the pore to permit gas exchange. This matches label B.

Step 2. Locate the flanking rows (A). On either side of the mound, compact rows of suberised, dead cells continue from the normal periderm of the stem surface. This protective outer layer is the phellem (cork), also produced by the phellogen. This matches label A.

Step 3. Locate the meristematic arc (D). Beneath both the complementary cells and the phellem, a thin continuous layer of actively dividing cells arcs across the base of the lenticel and the surrounding stem. This is the phellogen (cork cambium) — the meristem that cuts off phellem/complementary cells outward and phelloderm inward. This matches label D.

Step 4. Locate the innermost layer (C). Below the phellogen lies a layer of living, thin-walled parenchymatous cells — the phelloderm, formed on the inner face of the phellogen. This matches label C.

Step 5. Match to the options. A = phellem, B = complementary tissue, C = phelloderm, D = phellogen corresponds exactly to option (a).

Work outward-to-inward through the periderm/lenticel anatomy — the loosely packed filling cells at the pore are complementary cells, the compact cork rows flanking it are phellem, the actively dividing arc beneath is phellogen, and the innermost living layer is phelloderm — then map each identification onto its labelled position in the figure.

• Confusing complementary cells (loosely arranged, filling the pore) with phellem (compactly arranged, flanking the pore) because both sit near the surface.
• Swapping phellogen and phelloderm since both lie in the inner part of the periderm, only one cell layer apart.
• Assuming the outer protective cork layer must be 'phellogen' because the names look similar, instead of remembering phellogen is the actively dividing middle layer, not the outer protective layer (phellem).