Cork cambium is otherwise called

In the primary tissues of the stem, the cambium separating xylem and phloem is called

In a stem which is covered by periderm and in which stomata are absent, gaseous exchange takes place through

Desert grasses often roll their leaves due to presence of

A transverse section of the trunk of a tree shows concentric rings which are known as growth rings. How are these rings formed ? What is the significance of these rings ?

Give explanation about cork cambium.