A meristematic (cell-dividing) region occupying the whole of a certain transverse zone of the thallus, and cutting off new cells to add to the permanent tissue on both sides.
Stems. But in nearly all perennial Dicotyledons, in all dicotyledonous and gymnospermous trees and shrubs and in fossil Pteridophytes belonging to all the great groups, certain layers of cells remain meristematic among the permanent tissues, or after passing through a resting stage reacquire menstematic properties, and give rise to secondary tissues.
Mark a cessation of growth in the Diagrammatic transverse more internal meristematic rings.
The antheridia and archegonia are produced above the meristematic zone, and are more or less sunk in the tissues of the prothallus.
A meristematic zone forms a short distance outside the xylem, from which secondary tissue is developed both internally and externally; that to the inside contains both xylem and phloem elements.
Such meristematic layers are called secondary meristems. There are two chief secondary meristems, the cambium and the phellogen.