Question

According to histogen theory, epidermis is formed by

• A. Dermatogen
• B. Protoderm
• C. Periblem
• D. Plerome

Answer 1

Answer: (A)

Dermatogen

• The histogens at the shoot and root tip in plants as these are derived from the apical meristematic tissues according to the histogen theory given by Hanstein.
  
• It consists of three distinct layers:-
  

1. Dermatogen is the primary meristem that forms the outer most layer of a plant or a plant part and forms the epidermis.
   
2. Periblem is a primary meristem which is located between the plerome and the dermatogen and it forms the cortex.
   
3. Plerome is the primary meristem that forms the central core of a plant or plant part which gives rise to the stele (includes the vascular tissue, pith and pericycle).
   

• The part of plerome from which vascular tissues are formed is called procambium.
  
• So the correct answer is 'Dermatogen'