ISA Certified Arborist Practice Exam

The term for the zone where new growth occurs in a tree is the apical meristem. This is a region of actively dividing cells located at the tips of roots and shoots. The cells in the apical meristem differentiate to produce new tissues, allowing the tree to grow taller and develop new branches and foliage.

This growth occurs primarily during the growing season when conditions such as temperature and moisture are favorable. The apical meristem is essential for the vertical growth of the tree, contributing to its overall height and the formation of new leaves and buds.

In contrast, the cambium, though also a vital layer involved in growth, specifically refers to the lateral meristem responsible for the secondary growth (width) of stems and roots rather than new growth at the tips. The root system refers to the anchor and nutrient-absorbing portion of the tree, while heartwood is the older central wood of a tree, which no longer participates in growth and serves primarily for structural support. Each of these other terms denotes significant aspects of tree biology but does not describe the specific zone of new growth found in the apical meristem.