Artemesia
Tagetes
Chrysanthemum
Centipeda
Artemesia
Santonin was a drug which was widely used in the past as an antihelmintic, a drug which expels parasitic worms by paralyzing them and allowing them to be passed outside the body. Santonin was developed by German chemists by extracting the chemical from Artemisia cina. Previously Artemisia was used as an antihelmintic remedy. So, the correct answer is 'Artemesia'.