Lateraalimeristemit

Lateraalimeristemit, often translated as lateral meristems, are a type of plant meristem responsible for secondary growth, leading to an increase in girth or diameter of stems and roots. Unlike apical meristems, which are found at the tips of shoots and roots and are responsible for primary growth (length increase), lateral meristems are arranged in cylinders or cylinders within the plant body.

There are two main types of lateral meristems in vascular plants: the vascular cambium and the cork cambium. The vascular cambium is a cylindrical layer of actively dividing cells located between the xylem and phloem tissues. Its activity produces secondary xylem (wood) towards the inside and secondary phloem (inner bark) towards the outside. This continuous production of new vascular tissue is what causes the thickening of woody stems and roots.

The cork cambium, also known as the phellogen, is another cylindrical meristem that arises in the outer tissues of stems and roots, typically in the cortex or pericycle. It produces cork (phellem) to the outside and often a layer of phelloderm to the inside. The cork cells are impregnated with suberin, making them waterproof and providing protection against mechanical injury, desiccation, and pathogens. Together, the cork cambium and its derivatives form the periderm, which replaces the epidermis in older stems and roots, constituting the outer bark. Secondary growth enabled by lateral meristems is crucial for the structural support and longevity of many plant species, particularly trees and shrubs.