Meristem

From Greek meristos — "divisible" — the formative tissue of plants that retains for a long time the ability to divide and give rise to new cells; it is characterized by high metabolic activity. Some meristem cells — initials — remain at an embryonic phase of development and, by dividing, ensure the continuous increase of the plant's mass; other meristem cells gradually differentiate, forming vari…

From Greek meristos — "divisible" — the formative tissue of plants that retains for a long time the ability to divide and give rise to new cells; it is characterized by high metabolic activity. Some meristem cells — initials — remain at an embryonic phase of development and, by dividing, ensure the continuous increase of the plant's mass; other meristem cells gradually differentiate, forming various permanent tissues (protective (dermal), conductive (vascular), mechanical, fundamental (ground), etc.).

In higher plants the meristem arises from the promeristem of the embryo, which gives rise to apical (terminal) and lateral meristems. Apical meristems — the growth cones of the shoot and root — are laid down in the embryo very early. The formation of cotyledons and the initiation of leaf primordia on the shoot apical meristem causes the differentiation of lateral meristems into procambium and cambium.

During the plant's growth meristems are partially retained in its roots, in shoot nodes, buds, stem internodes, etc. The increase in width of the blades of leaf primordia is due to the marginal meristem. Because the capacity to divide is potentially retained in almost all living mature tissues (except sieve tubes), plants can give rise to new, so-called secondary meristems, for example phellogen, which forms cork tissue, wound meristem producing callus, and others.