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Plant Biology - Root Morphology

Introduction:
A plant can be studied by its internal constitution and by its external characters. A typical flowering plant has a main unbranched or branched axis. The main axis is divided into two parts – an underground root part and an above ground shoot part.

Root system develops from the radicle and the shoot system develops from the plumule. Shoot contains stem, leaves and flowers which produces seeds and fruit and from that new plant is developed.


Root system:
The underground part of the plant axis is called root.  It develops from the radicle and does not contain chlorophyll. It is positively geotropic, negatively phototropic and positively hydrotropic.

The initial part of the root which develops from the radicle is called primary root and from that secondary and tertiary root develops and branches develops.

Some plant contains strong and longer primary root which is called taproot such as dicotyledons. When root is develops from other part of the plant such as leaf or stem, then it is called adventitious root. Monocotyledons contain very short and thin primary root from which fibrous are developed and they are called as fibrous roots.

Section of Root:
Root is divided into different sections - Apical meristematic section surrounded by root cap, elongation section and the maturation section.

Apical meristematic tissues are present at the growing tips of roots and increase the length of root by adding new cells. Root cap is present surrounded the apical meristematic tissues to protect them.

Elongation section contains higher region of root and responsible for growth of root. Maturation region contains all maturated cells and differentiated into root hairs and root branches.

Function of Root

  1. To fix the plant in the soil
  2. To provide support to the plant.
  3. To absorb water from the soil and delivered into different parts of the plant.
  4. To store the food prepared by leaves (example – carrot, radish, beet, sweet potato etc)
  5. Provides mechanical support when underground root system is superficial
  6. In climber and twine plants, adventitious roots are developed form nodes and internodes of the stem and help the plant in climbing.
  7. Sometimes carry outs photosynthesis (Example – Tinospora).
  8. Helps in breathing for mangroves which develops in waterlogged soil of creeks near ocean’s coastal region.  (Example – Rhizophora, Avicennia)
  9. Absorb the moisture for orchid who lives as epiphytes on the branches of other trees.
  10. Roots of parasite plants help in absorbtion of water and food and provide support for fixing on other plant (Example – Cuscuta, Viscum)
  11. Symbiotic root provides habitat and nutrition to the bacteria and in return gets absorbable salts of nitrogen through nitrogen fixation.
  12. Adventitious root contains adventitious buds which is responsible for reproduction of plants like sweet potatoes.

Self study:
Q-1: Root system of the plant develops form the following region?
  1. Radicle
  2. Plumule
  3. Seeds
  4. Fruits
Answer: Root system of the plant develops from the radicle

Q-2: Adventitious roots are developing from ………………..

  1. Fruit
  2. Leaves or Stem
  3. Seeds
  4. Radicle.
Answer: Adventitious roots are developing from leaves or stem.

Q-3: Root that provides habitat and nutrition to the bacteria is called ………

  1. Parasite root
  2. Adventitious root
  3. Fibrous root
  4. Symbiotic root
Answer: Root that provides habitat and nutrition to the bacteria is called symbiotic root.

 

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