In temperate regions, trees produce distinct layers of secondary xylem due to seasonal variations in growth rates. Spring wood, characterized by large, thin-walled vessels, and summer wood, with smaller, denser cells, together form a single annual ring. Counting these rings allows for the determination of the tree's age, a process known as dendrochronology.

Commercial cork is obtained from the bark of the cork oak tree, scientifically known as Quercus suber. The bark is harvested periodically without killing the tree. The unique properties of cork, such as its impermeability to water and gases and its elasticity, are due to the presence of suberin in the cell walls of the phellem tissue.

In the vascular cambium, fusiform initials can be arranged in two ways. When they are aligned in horizontal rows, the cambium is described as 'storied' or 'stratified'. This arrangement is common in many woods. Conversely, if the ends of the cells overlap and are not aligned in horizontal rows, the arrangement is referred to as 'non-storied' or 'non-stratified'.

Dendrochronology is the scientific method of dating based on the analysis of tree growth rings. In temperate climates, trees produce one ring of xylem per year, reflecting seasonal growth variations. By counting these annual rings, researchers can accurately determine the age of the tree and analyze historical climate patterns.

Interxylary phloem, also known as included phloem, refers to strands or groups of phloem tissue that are produced by the vascular cambium and become embedded within the secondary xylem during the process of secondary growth in certain plant species.

Bark formation depends on the pattern of phellogen (cork cambium) activity. When the phellogen develops in overlapping, discontinuous arcs or strips, the resulting periderm layers are also discontinuous. As the stem expands, these layers peel off in irregular, plate-like, or scale-like pieces. This type of bark is known as scaly bark, which contrasts with ring bark, where the phellogen forms a continuous cylinder around the stem.

The vascular cambium is a lateral meristem found in dicotyledonous plants. It is responsible for secondary growth, producing secondary xylem towards the interior and secondary phloem towards the exterior of the stem. This process increases the girth of the plant over time.

Witches' broom is a deformity in woody plants where the natural growth pattern is disrupted, leading to a dense mass of shoots. This is often associated with hypertrophy (excessive cell growth) or hyperplasia (excessive cell division) induced by pathogens like fungi, viruses, or phytoplasmas, which disrupt the plant's hormonal balance and apical dominance.

Lenticels are raised pores in the stem of woody plants that allow for gas exchange between the internal tissues and the atmosphere. Unlike the typical cork cambium (phellogen) which produces tightly packed cells, the phellogen in the region of a lenticel produces loosely arranged, rounded cells with significant intercellular spaces, facilitating the diffusion of oxygen and carbon dioxide.

The phellogen (cork cambium) is a lateral meristem that produces cells on both sides. The cells produced toward the outside differentiate into phellem, commonly known as cork, which provides protection and insulation to the plant stem during secondary growth.