tissue introduction meristematic tissue ground tissue dermal tissue vascular tissue

Meristematic tissues are responsible for the division of new cells... they are zones of actively dividing cells

Before we precede, we should first recognize that growth in plants includes two stages:

Cell division occurs solely in meristematic regions, while expansion may occur anywhere.

Thus in a single plant there are zones of young dividing cells, maturing cells, and mature cells.

We will go into more detail on meristematic regions when we go over the stem and root individually, but for now an introduction is sufficient

Let us recognize that there are 3 meristematic regions in the plant:

I. Apical meristems are located at the apices or tips - at root and shoot tips and are directly involved in their elongation
They create derivatives which form primary growth.

the 2 excellent images below were taken from: Koning, Ross E. "Tissue Types". Plant Physiology Website. 1994. http://koning.ecsu.ctstateu.edu/plant_biology/tissuetypes.html (2/99).

*in shoots, plants protect their meristems with young leaves and by forming dormant reserve meristems (i.e., buds),
that protect their apical meristems with a root cap

II. Lateral meristem are responsible for horizontal expansion

a.Vascular meristem- internal growth in girth which involves secondary tissues (xylem and phloem). In the fasicular region the cambial cells which divide toward the center form xylem tissue and towards the outside phloem tissue.

Interfasicular indicates the cambium between the 'fasciles of xylem & phloem.

b. Cork cambium- external girth growth beyond the phloem area. They form the characteristic corky layer
as well as an internal layer. We'll cover these in more detail in the section of the stem.

III. Intercalary meristem-

* occurs between mature tissues sections in the vicinity of the nodes or leaf attachment;

* common in grasses (occur at bases of nodes);

* helps regenerate parts removed (by lawnmowers, herbivores, etc.)

modified from: http://creator.ns.msu.edu/prl/kende.html