Which one of the following tissues is responsible for increase of girth in the stem of a plant?

The increase in the girth or thickness of a plant stem is known as secondary growth. This process is primarily facilitated by lateral meristems, which include the vascular cambium and cork cambium [3]. Unlike apical meristems that contribute to length, lateral meristems are cylindrical tissues that produce secondary xylem and phloem, allowing the tree to grow wider each year [2]. Specifically, the vascular cambium adds layers of secondary vascular tissue, while the cork cambium replaces the epidermis with tougher periderm [3]. In contrast, tracheids are specialized water-conducting cells within the xylem [1], the pericycle is involved in lateral root initiation [3], and intercalary meristems are responsible for longitudinal growth at the nodes, particularly in monocots like grasses [3]. Therefore, the lateral meristem is the specific tissue responsible for radial expansion and increased stem girth.

Sources

1. [3] https://www.sciencedirect.com/topics/immunology-and-microbiology/xylem-cell
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Transport of water > p. 94
3. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 13: Plant Diversity of India > Cambium: > p. 204