Meristematic Tissue I Primary Meristem and Secondary Meristem II Free Notes II #biology #botany #basics #developmentalbiology

Plant body is polar means it has two ends one is root end and other one is shoot end.

At the tip or ending of each stem branch is a Shoot Apical Meristem-SAM

At tip or end of root is Root Apical Meristem-RAM

RAM and SAM are the two Meristem, they are site for Growth and Differentiation of cells

What are Meristematic Cells?

The meristematic cells are undifferentiating dividing cells that do not acquire fate or gain fate.

Cells are small with dense cytoplasm

They have Numerous Plasmodesmata.

Meristematic tissues are of two main kinds:

PRIMARY MERISTEM:

• Primary Meristem produces primary tissue of plant body that helps in elongation

• They are responsible for Primary Growth of plant.

• Primary Growth means increase in length of plant.

PRIMARY MERISTEM is of three main types:

PROTODERM: Produces outer layer of plant body epidermis/ epiblema.

PROCAMBIUM: The cells produce primary xylem and phloem by differentiation.

GROUND MERISTEM: They differentiates into pith and cortex of root, stem and mesophyll of leaves.

SECONDARY MERISTEM

• Secondary meristem produces secondary tissue that increases the width of plant, they enable growth in lateral direction.

• They are Responsible for Secondary Growth in Plants.

• Secondary growth refers to increase in girth or thickness or diameter of a plant.

SECONDARY MERISTEM is of two types:

Vascular Cambium that produces secondary xylem and phloem

Cork Cambium produces Periderm.