ISA Certified Arborist Practice Exam

The cambium is a vital layer of tissue found in trees that plays a critical role in their growth. Its primary function is to produce new cells, which contributes to the increase in the tree's girth or diameter. The cambium is a thin layer of living cells located between the bark and the wood of the tree. During the growing season, it generates new phloem cells towards the outside and new xylem cells towards the inside. This process allows the tree to expand, enabling it to grow thicker and stronger over time.

Understanding the function of the cambium is essential for comprehending how trees develop and adapt to their environments. The other options refer to functions that are important for a tree's survival but are performed by different tissues or systems; for example, nutrient storage occurs in the parenchyma cells, water conduction primarily happens in the xylem, and structural stability is provided by the combination of wood and bark. The cambium's unique role in cell production distinguishes it as the primary tissue for growth in trees.