Cork cambium and vascular cambium are lateral meristems responsible for secondary growth in plants, increasing girth in stems and roots. Procambium and protoderm are primary meristems involved in initial lengthwise growth. The correct answer for Q.31 is (A) and (D).

Option Analysis

• (A) Cork cambium: This secondary meristem, also called phellogen, forms the periderm including cork (phellem) outward and phelloderm inward, providing protection during secondary growth.

• (B) Procambium: A primary meristem from apical regions that differentiates into primary xylem and phloem for lengthwise primary growth, not lateral thickening.

• (C) Protoderm: The outermost primary meristem that develops into the epidermis, including stomata and hairs, for surface protection in primary growth.

• (D) Vascular cambium: This lateral meristem produces secondary xylem inward and secondary phloem outward, enabling girth increase in woody plants.

Lateral meristems drive secondary growth in plants, boosting stem and root thickness for structural support in dicots and gymnosperms. These tissues, including cork cambium and vascular cambium, form cylindrical layers unlike primary meristems focused on length.

Types of Meristems

Meristems divide into apical (length growth), intercalary (internode elongation), and lateral (girth increase). Lateral meristems arise later as secondary tissues from permanent cells.

• Primary meristems: Protoderm (epidermis), procambium (vascular), ground meristem (cortex/pith).

• Secondary/lateral: Vascular cambium, cork cambium.

Functions in Growth

Vascular cambium divides periclinally between xylem and phloem, adding annual rings visible in tree trunks. Cork cambium replaces epidermis with bark for wound healing and water impermeability.

This table highlights differences for CSIR NET preparation on plant anatomy. Monocots lack robust lateral meristems, limiting woodiness.