what are meristems, lateral meristems, vascular cambium, and cork cambium??

Meristem (or meristematic tissue) is composed of immature and continuously dividing cells. These cells undergo differentiation to form the other kinds of tissues.

Meristem can be further classified based on the position or locations of meristematic tissues. They are of three types- apical, intercalary and lateral meristem. 

Lateral meristem: They are present on the lateral side of stems and roots. Lateral meristem is responsible for the radial  growth of plants. 

The lateral meristem consists of two types of tissues- vascular cambium and cork cambium.

1. Vascular cambium- It gives rise to new vascular tissue.

2. Cork cambium or phellogen- It arises later to replace the ruptured epidermis of the expanding plant body.