Both stems and roots grow typically from their tips. This growth is centered just back from the apex of the stem or root in a particular zone of cells that undergo elongation. As these cells elongate they mature and can specialize.

To permit this growth from their tips, seed plants must repeatedly form new cells above the growth zone. This production of new cells is critical to replenish the growth zone after a set of cells have elongated and matured. These new cells are formed in regions called apical meristems. Meristem is derived from the Greek word meristos, which means "to divide." Meristems are active regions of mitotic cell division (a process that results in the formation of new cells). At the tips of all stems, including the main stem and branches, and roots we can find apical meristems.

A head of cabbage can be thought of as the highly enlarged apical meristem of a shoot. Shoot apical meristems are regions not only of new cell production, they are also the location where stems make new leaves. The leaves of the cabbage arch over the apical meristem. This curvature of the leaves is typical of what we find at the apical meristem. Cabbage and shoot apical meristems have numerous leaves positioned very close together. The internodes near the apical meristem have not yet elongated.

Cabbage

Section of cabbage shows it has the attributes of a shoot apical meristem.

If we cut a cabbage in half along its length, we can see that the very apex of the stem at its core has a small dome on which there are no leaves. This is the actual shoot apical meristem in which cell division of the stem is located.

Shoot apical meristem of cabbage