The pericycle is a thin layer of cells found just inside the endodermis and surrounding the vascular tissues (xylem and phloem) in roots and sometimes in stems. It plays several important roles in plant growth, development, and transport.
Here are the main functions of the pericycle:
1. Formation of Lateral Roots
- The pericycle is the origin of lateral (side) roots.
- Cells in the pericycle become active and divide to form new root primordia (young roots) that grow outward through the cortex and epidermis.
- This helps the plant spread and absorb more water and nutrients.
2. Secondary Growth
- In dicot roots, the pericycle contributes to secondary growth (increase in thickness).
- It gives rise to parts of the vascular cambium and cork cambium, which produce secondary xylem, phloem, and protective tissues.
3. Support and Protection
- The pericycle acts as a protective boundary between the vascular tissues and the outer root layers.
- It helps maintain the structure and integrity of the vascular cylinder (stele).
4. Storage
- In some plants, pericycle cells store starch, oils, or other nutrients, serving as a reserve for plant growth.
5. Regeneration and Wound Healing
- The pericycle retains the ability to divide and form new tissues, helping in repair and regeneration if the root is injured.
In simple terms, the pericycle is a living, active layer that helps form new roots, thicken the root, store food, and protect the vascular tissues, making it vital for root growth and plant health.