What type of growth is characterized by apical growth in plants?

The type of growth characterized by apical growth in plants is indeed the lengthening of stems and roots. Apical growth occurs at the tips of the stems and roots, where the apical meristem is located. This region of actively dividing cells enables the plant to elongate and increase its height or depth. As these cells divide and differentiate, they contribute to the growth in length, allowing the plant to reach for sunlight and expand its root system into the soil.

While thickening of the plant, branching and lateral expansion, and formation of new leaves and flowers are all legitimate growth processes that occur in plants, they are not the direct result of apical growth. Thickening is associated with secondary growth and the activity of cambium cells, branching involves the activity of lateral meristems, and the formation of new leaves and flowers can occur from various growth patterns but does not specifically align with apical growth. Thus, lengthening of stems and roots is the defining characteristic of apical growth.