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  • In which of the following porous wood is absent?Option: 1 GnetumOption: 2 Ephedra

In which of the following porous wood is absent?

Option: 1

Gnetum


Option: 2

Ephedra


Option: 3

Selaginella


Option: 4

None of these


Answers (1)

best_answer

 

 

 

Vessels:

  • These arise from procambium during the primary growth and from vascular cambium during secondary growth.
  • The pattern of secondary wall deposition is determined by the microfibrils.
  • Vessels are made up of vessel elements placed one over the other.
  • Vessel elements have perforated end walls. 
  • Hence, vessels are multicellular pipe-like structures.
  • They have comparatively a wider lumen than tracheids.
  • At maturity, they are devoid of protoplasm and are dead.
  • In pteridophytes and gymnosperms, the vessels are absent. Their wood is called the non-porous wood.
  • In angiosperms, the vessels are present. Their wood is called porous wood.

TIP: 
Ephedra and Gnetum are the gymnosperms that have vessels. Selaginella and  Pteridium are the pteridophytes that have vessels.
Winteraceae, Trochodendraceae and Tetracentraceae of Angiosperms do not have vessels.
 

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Ephedra and Gnetum are the gymnosperms that have vessels. Selaginellaand  Pteridium are the pteridophytes that have vessels. Winteraceae, Trochodendraceae and Tetracentraceae of Angiosperms do not have vessels.

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vishal kumar

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