Generally speaking, "Chrysanthemum" is a plant belonging to the genus Chrysanthemum in the family Asteraceae, but there are about 200 species in the world. Of these, there are about 20 species of "wild chrysanthemum" that grow naturally in Japan, and most of them are grown for ornamental purposes called "Chrysanthemum (florists' daisy)". It came to Japan via Korea in the old days, but it was originally a medicinal plant. Also, the reason why there is no other way to read the kanji "Kiku" is that it was used as a technical term for medicine. Depending on the size of the flower head, it is classified into "Oo-giku" (large chrysanthemums) with a diameter of 18 cm or more, "Chu-giku" (medium chrysanthemums) with a diameter of 9 to 18 cm, and "Ko-giku" (small chrysanthemums) with a diameter of less than 9 cm.