06 Plant Water Relation - part 02 - Water absorbing organ

06 Plant Water Relation - part 02 - Water absorbing organ


Water absorbing organ: 
Root :

  • Root is the main organ of water and mineral absorption. 
  • In terestrial plants, plants absorb water in the form of liquid from the soil. 
  • Epiphytic plants like orchids absorb water vapours from air with the help of epiphytic roots having special tissue called velamen. 
  • Typical root is divisible into four different regions. 
  • In the zone of absorption, epidermal cells (epiblema cells) form unicellular hair like extensions called root hairs.
Structure of root hair : 

  • Root hair is cytoplasmic extension (prolongation) ofepiblema cell. 
  • Each root hair may be approximately 1 to 10mm long and tube like structure. 
  • It is colourless, unbranched, short-lived (ephemeral) and very delicate. 
  • It has a large central vacuole surrounded by thin film of cytoplasm, plasma membrane and thin cell wall, which is two layered. 
  • Outer layer is composed of pectin and inner layer is made up of cellulose. 
  • Cell wall is freely permeable but plasma membrane is selectively permeable. 

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