AP BIOLOGY

Detailed explanation-1: -Occurrence of secondary growth due to the activity of two laterally positioned meristems, viz. the vascular cambium and the phellogen (cork cambium) is a common feature of the gymnosperms and dicotyledons.

Detailed explanation-2: -Secondary Growth There are two types of meristem in the plant stem: apical and lateral. As we just reviewed, primary growth occurs at the apical meristem and increases plant stem length. Secondary growth is growth at the lateral meristem and increases the girth of the stem.

Detailed explanation-3: -All secondary meristems are lateral in position but all internal meristems are not secondary in origin.

Detailed explanation-4: -The lateral meristem tissues are responsible for the secondary growth of plants. The secondary growth of plants increase in stem thickness and it is due to the activity of the lateral meristems, which are absent in herbs or herbaceous plants.