Primary vs Secondary Meristem
Meristems are a group of plant cells that remain in a continuous state of division. The meristematic cells continuously produce new cells through the life of the plant. In previous posts, we have discussed the Characteristics of Meristematic Cells, Classification of Meristems and Difference between Meristematic and Permanent Tissues. The present post describes the Similarities and Difference between Primary and Secondary Meristem.
Meristems are classified into different categories based on different criterions. In one such classification, the meristems are classified into two groups based on the nature of cells giving them. These two groups are (1) Primary Meristem and (2) Secondary Meristem.
Primary Meristem: Primary meristems are the direct descendants of the embryonic cells. They continuously involved in the cell division and growth process of the plant. Example: apical meristem of shoot apex and root apex.
Secondary Meristem: Secondary meristems are the meristematic tissue arises from the permanent tissues. Secondary meristems are usually lateral meristems and are responsible for the increase in thickness of the plant. Example: vascular cambium and cork cambium (phellogen).
A Vascular Bundle with Cambium (Primary Meristem)
Similarities between Primary and Secondary Meristem
Ø Both primary and secondary meristems are actively dividing cells.
Ø Both are parenchymatous cells.
Ø Both contain prominent nucleus with granular cytoplasm.
Ø Both are metabolically very active.
Ø Both are undifferentiated cells.
Ø Cells are closely packed without intercellular spaces.
Difference between Primary and Secondary Meristem
Sl.No. Primary Meristem Secondary Meristem 1 Derived from the embryonic cells (promeristem). Derived from the permanent tissue. 2 Cells are usually isodiametric. Cells are elongated, barrel-shaped or rectangular shaped. 3 Forms the primary tissue. Always form the secondary tissue. 4 Cause primary growth of the plant Cause secondary growth of the plant 5 Formed when the plant starts its growth. Formed much latter, usually after the primary growth. 6 Primary meristematic cells are devoid of vacuoles. Secondary meristematic cells contain plenty of vacuoles. 7 Usually cause growth towards the longitudinal direction (height). Usually cause growth towards the radial direction (width).
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@. Characteristics of Meristematic Cells
@. Difference between Meristem and Permanent Cells