Meristematic Tissues:

1. Group of cells that are preparing to divide or are in continuous state of division or have the capacity to
   divide.
2. In early embryonic stages all the cells are meristematic in nature but later on this activity of diyison get restricted to certain specific regions called meristem (meristem means = divisible).
3. Meristemetic tissue are found in growing regions of plants and plants grow by these tissue.

(A) Based on origin and method of development meristems are of following three types.

1.Promeristem (= primordial meristem) –

• A group of cells originate from embryo end therefore called primordial or embryonic meristem.
• These tissue cells represent primary stages of meristemetic cells.
• These tissue are present in a small region at the apices of shoots and roots.
• Promeristem give rise to primary meristem.

2. Primary Meristem –

• The meristematie cells that originate from promeristem are primary meristems.
• These cells are always in active state of division and give rise to primary permanent tissues.
• They are present below the promeristem at shoot and root apices, at the apex of leaves and in intercalary parts.
• Protoderm (produces epidermal tissue system), procambium (produces primary vascular elements) ground meristem (produces cortex and pith) are kinds of primary meristem.

3. Secondary Meristem –

• They originate from primary permanent tissues.
• They do not have their own promeristem.
• Develop at a later stage and give rise to secondary permanent tissues.
• The cambium of root, vascular cambium (from interfascicular regions in dicots when secondary growth is needed and as cork cambium when formation of periderm and healing of wounds is needed.