Tissues

2 Plant Tissues

  • Plant tissue system links different organs of plants.
  • A plant tissue is made up of group of cells that may be either similar or dissimilar in structure, function and origin.
  • Plants of higher level show this level of cellular organization.
  • Plant tissues are divided into two types of tissue:
    • Meristematic tissue
    • Permanent tissue
plantTissues

Meristematic Tissues (Meristems)

STRUCTURE:

  • They may be spherical, oval, polygonal or rectangular in shape.
  • They are compactly arranged and do not contain any intercellular space between them.
  • They lack vacuoles.
  • Cells of meristematic tissue are very active.
  • They have dense cytoplasm, thin cellulose walls and prominent nuclei.

FUNCTION:

  • Cells of meristems divide continuously.
  • Cells help in increasing the length and width of the plant.
  • Cells help in growth of the plant.
  • The place of injury in plants is healed up by the formation of new cells by meristems.

OCCURRENCE:

  • They are found in the growing regions of the plant, like in the tips and nodes of plant parts like stems, branches, roots and shoots.
  • According to the position of  the meristematic tissues, they are divided into three parts:
    • Apical
    • Lateral
    • Intercalary

Apical meristems:

  • Occurrence: These are situated at the growing tip of stems and roots, i.e. at shoot apex and root apex. Apical meristems are also found at apices of the leaves.
  • Function: They bring about the elongation of the root and stem which leads to the primary growth.

Lateral meristems:

  • Occurrence: These are found beneath the bark and in vascular bundles of dicot roots and stems.
  • Function: It causes the organ to increases in diameter and girth. This is called secondary growth.

Intercalary meristems:

Occurrence: They are located at the base of leaves or internode. e.g. stems of grasses and other monocots.
Function: They produce an increase in the length of an organ such as leaves and internodes.

Permanent Tissues:

  • Cells derived from division of meristematic tissue take up specific role and lose the ability to divide.
  • This results in the formation of permanent tissue.
  • Their characteristics include:
    • Thin living cells or thick dead cells
    • Intercellular spaces which are either present or absent
    • Less dense cytoplasm where single large vacuole is embedded
  • Different types of permanent tissues are formed due to differences in their specialization.
permanentTissue

Permanent tissues can be of two forms:

  • Simple
  • Complex

Difference between merismatic tissue and permanent tissue:

Meristematic tissue Permanent tissue
Its component cells are small, spherical or polygonal and un-differentiated. Its component cells are large, differentiated with different shapes.
Cytoplasm is dense. Vacuoles are nearly absent.

Large central vacuole occurs in living permanent cells.

Intercellular spaces are absent. Intercellular spaces are often present.
Cell wall of its cell is thin and elastic. Cell wall of its cells is thin or thick.
Nucleus of each cell of this tissue is large and prominent. Nucleus of each cell of this tissue is less conspicuous.
Its cells grow and divide regularly. Its cells do not normally divide.
It is a simple tissue. It can be simple, complex or specialized.
Its cells are metabolically active. Metabolic rate of cells of this tissue is slow.
Cell organelles of its cells are simple. Cell organelles of its cells are well developed.
Cells of this tissue do not contain crystals and other inclusions. Cells of this tissue possess crystals and other inclusions.
Its cells are living. Its cells may be living or dead.
It provides growth to the plant. It provides protection, support, conduction photosynthesis, storage, etc.

Start your learning Journey !

Tutormate-googleplay
Tutormate-AppleStore
Get SMS link to download the app