Question

Histogen tissues are classified on the basis of _________.

• A. Plane of division
• B. Type of cells they form
• C. Position
• D. Origin

Answer 1

Answer: (B)

Type of cells they form

• The shoot apical meristem (SAM) form three distinct meristematic zones called the histogens.
  
• These histogens are present at the growing tips of a stem or a root.
  
• These tips consist of three histogens based on the type of cells they form.
• Each of these histogens gives rise to tissues which are different from one another- dermatogen, periblem, plerome (principle tissues)
  
• The dermatogen or the outer layer gives rise to the epidermis, periblem or middle layer gives rise to the cortex as well as the endodermis, plerome or the inner layer gives rise to vascular tissues.
  
• This is called histogen theory which was proposed by Hanstein in 1870.
  
• So, the correct answer is 'Type of cells they form'