Biology - Tissues


  • A group of cells that are similar in structure and work together to accomplish a particular function is known as tissue.

  • Tissues are categorized as −

    • Plant Tissue &

    • Animal Tissue

  • Let’s discuss them in brief −

Plant Tissue

  • Following are the major types of plant tissue −

    • Meristematic Tissues

    • Permanent Tissues

      • Simple Permanent Tissues

        • Parenchyma

        • Collenchyma

        • Sclerenchyma

        • Epidermis

      • Complex Permanent Tissue

        • Xylem

        • Phloem

Meristematic Tissue

  • Meristematic tissue mainly consists of actively dividing cells, and helps in increasing the length and thickening the stems of the plant.

  • Meristematic tissue, commonly, present in the primary growth regions of a plant, for example, in the tips of stems or roots.

  • Depending on the region (where the meristematic tissues are found); meristematic tissues are classified as apical, lateral, and intercalary (see the image given below).

Types of Meristematic Tissue
  • Apical meristem (as shown in the above image) is present at the growing tips of stems and roots and helps in their growth.

  • Lateral Meristem is found in stem or root region and helps in their growth.

  • Intercalary meristem is found at the base of the leaves or internodes (on twigs) and helps in growth.

Permanent Tissue

  • Cells of meristematic tissue later differentiate to form different types of permanent tissue.

  • Permanent Tissue is further categorized as −

    • Simple Permanent Tissue and

    • Complex Permanent Tissue

Simple Permanent Tissue

  • Simple Permanent Tissue further categorized as −

    • Parenchyma

    • Collenchyma

    • Sclerenchyma

    • Epidermis

  • Parenchyma tissue provides support to plants and also stores food.

Parenchyma Tissue
  • Sometimes, parenchyma tissue contains chlorophyll and performs photosynthesis, in such a condition, it is known as collenchyma.

Collenchyma Tissue
  • The collenchyma tissue provides flexibility to plant and also provides mechanical support (to plant).

  • The large air cavities, which are present in parenchyma of aquatic plants, give buoyancy to the plants and also help them float, are known as aerenchyma.

  • The Sclerenchyma tissue makes the plant hard and stiff. For example, the husk of a coconut is made up of sclerenchymatous tissue.

Sclerenchyma Tissue
  • The cells of Sclerenchyma tissue normally are dead.

  • The outermost layer of cells is known as epidermis.

  • The epidermis is usually made up of a single layer of cells.

  • The entire surface of a plant has the outer covering of epidermis, which protects all the parts of the plant.

Complex Permanent Tissue

  • The complex tissue, normally, consists of more than one type of cells which work together as a unit.

  • Complex tissues help in the transportation by carrying organic material, water, and minerals up and down in the plants.

  • Complex Permanent Tissue is categorized as;

    • Xylem and

    • Phloem

Xylema and Phloem
  • Xylem, normally, consists of tracheid, vessels, xylem parenchyma, and xylem fibers.

  • Xylem is accountable for the conduction of water and mineral ions/salt.

  • Phloem, normally, is made up of four types of elements namely −

    • Sieve tubes

    • Companion cells

    • Phloem fibers and

    • Phloem parenchyma

  • Phloem tissue transports food from leaves to other parts of the plant.