2. Content
• What is Meristem?
• Classification of Meristem
• Apical Meristem
3. What is Meristem?
• A region of plant tissue , found chiefly at the
growing tips of roots and shoots and the
cambium consisting of actively dividing cells
forming new tissue.
• A meristematic tissue consists of a group of
cells which remain in continuous state of
division or they retain their power of
division.
4. Classification of Meristems
• Meristem Based on stage Development
• Meristems Based on origin of Initilating
• Meristems Based on position in plant Body
1. Apical Meristem
2. Intercalary Meristem
3. Lateral Meristem
• Meristems Based on function
5. Meristems Based on stage
Develpoment
• Promeristem or Primordial meristem:
1. Promeristem is the region of new growth in
a plant body where the foundation of new
organs or parts of oragans is initiated .
2. Sometimes it is also called primordial
meristem , urmeristem and embryonic
meristem.
6. Meristems Based on origin of
Initilating cells
1. Primary meristem
2. Secondary meristem
• Primary meristems:
1. The primary meristems are those that build up primary
part of the plant and consist in parts of promeristem.
2. In primary meristem,promeristem is always the earliest
stage.
3. The possession of promeristem continuously from an
early embryonic origin is characteristic of primary
meristem.
4. The main primary stems are the apices of roots,stems
and leaves ,similar appendages.
7. • Secondary meristems :
1. The secondary meristems appears later at a stage of
development of an organ of a plant body.
2. The seconary meristems always arise in permanent
tissue and they are always found lying lateral along
the of stem and root.
3. Sometimes some of the primary permanent tissues
actually the power of division and become
meristematic.
4. The secondary meristems are so called because they
arise as new meristems in tissue which is not
meristematic.
5. The most striking example of secondary meristem is
phell or cork cambium.
9. Meristems Based on function
• As regards their function a systems of classification of
meristems was proposed by Haberlandt in the end of 19th
century.
• He suggested that the primary meristem at the apex of the
stem and root is distinguished into three tissues –
protoderm,procambium and ground or fundamental
meristem.
• The protoderm is the outermost tissue which develops into
epidermis.
• The procambium develops into primary vascular tissues.
• The ground or fundamental medistem develops into ground
tissue and pith.
• They become differentiated into hypodemis, cortex,
endodermis,pericycle,pith, rays and pith.
10.
11. Apical Meristem
• The apical meristem includes the
meristematic initials and their immediate
derivatives at the apex of a shoot or root.
• The apical meristem thus delimited
corresponds approximately to the
promeristem,and to cotrast with the partly
develpoment derivatives of the
promeristem,i.e.,the protoderm ,the ground
meristem and the procambium.
12. 1. They are composed of immature cells which are
in a state of division and growth.
2. Usually the intercellular spaces are not found
among the cells.
3. The cells may be rounded , oval or polygonal in
shape they are always living and thin walled.
4. Each cell of meristematic tissue possesses
abundant cytoplasm and one or more nuclei in it.
5. The vacuoles in the cells may be quite small or
altogether absent.
13. Reference
• A Text Book of Botany Angiosperms by B.P.
Pandey
• https://en.m.Wikipedia.org
• https://www.slideshare.net
• www.biologydiscussion.com
