TISSUES

Plant Tissue

TISSUES

Introduction

• 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

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).

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

• 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.