Which of the following is not a lateral meristem?

The correct answer is Intercalary meristem.

To understand why intercalary meristem is not a lateral meristem, let us break down the classification of meristematic tissues in plants based on their position:

1. Apical Meristems:
These are located at the growing tips of stems and roots (apices). They are responsible for primary growth, which increases the length of the plant body.

2. Intercalary Meristems:
These meristems are derived from apical meristems and are located at the base of leaves or internodes (often seen in grasses). They help in regenerating parts removed by grazing herbivores and also contribute to the elongation of the stem. Since they are positioned between regions of mature, permanent tissues and contribute to primary longitudinal growth, they are classified as primary meristems, not lateral meristems.

3. Lateral Meristems:
These meristems occur on the lateral sides of stems and roots, running parallel to the longitudinal axis. They are responsible for secondary growth, which increases the thickness or girth of the plant. Examples of lateral meristems include:
- Phellogen (Cork cambium): Produces the protective corky outer layer (periderm).
- Interfascicular cambium: Forms between vascular bundles to assist in forming a continuous cambial ring for secondary vascular tissue development.

Since Intercalary meristem is responsible for elongation (primary growth) and is positioned between mature tissues rather than along the lateral sides, it is not a lateral meristem.