Identification of South Indian plant
I presume you are talking about Peperomia pellucida. It is called  Mashithandu in Malayalam. 



Reference: Wikipedia

You might like to go through this.


  Description
  
  Delicate, glabrous annual herbs; stems erect, 5-30 cm tall, pellucid,
  branched when well developed.
  
  Global Distribution
  
  Native of Tropical America; now Pantropical
  
  Indian distribution
  
  State - Kerala in all Districts