Overview

The vascular cambium is a thin cylinder of lateral meristem found in many seed plants. It adds thickness to stems and roots by producing secondary xylem toward the inside and secondary phloem toward the outside. It is common in woody eudicots and gymnosperms; most monocots lack a typical vascular cambium, although a few show unusual secondary thickening.

In a typical stem or root, the cambium lies between the xylem and phloem. It may begin as separate strips and later form a continuous ring. As the ring keeps dividing, the plant gains a wider transport system and, in woody species, a stronger body that can persist for many years.

Cell activity and growth

Cambium cells are small, thin-walled, and still capable of division, meaning they remain relatively embryonic compared with mature conducting cells. New cells formed to the inside usually become part of the water-conducting system, while those formed to the outside join the food-conducting system. This balanced production is essential for long-term transport as the plant enlarges.

Although vascular cambium is associated most strongly with stems and roots, only a few leaves develop a functional version of it. Most leaves complete their growth without major secondary thickening, which helps explain why they stay thin and flexible rather than becoming woody.

The vascular cambium is one of two major lateral meristems. The other is the cork cambium, which makes protective outer cells called cork. Together with other outer tissues, cork contributes to the bark of woody plants. In practical terms, vascular cambium builds the transport core, while cork cambium helps form the protective covering.

  • Primary growth: elongation from apical meristems at shoot and root tips.
  • Secondary growth: thickening driven by vascular cambium and, later, cork cambium.
  • Importance: supports larger bodies, greater transport capacity, and the formation of wood.

Because it keeps dividing for long periods, the vascular cambium is central to the development of trees and many shrubs. In plant anatomy, it is a key example of how meristematic tissue allows a body plan to keep changing after the main organs have already formed.