Sterilization, Insect Control and Herbal Dyes

Japanese Green Gentian

Japanese green gentian is also known as “toyaku” in Japanese, which literally means something like “effective medicine”. Its bitterness and effectiveness as a remedy for stomachaches is well known.

What is less widely known is that dying underwear in a brew made from this plant gets rid of fleas and lice. These are no longer a problem nowadays, but the protection it gave against insects was important to the ninja.

Chinese Cork Tree

The bark of this tall tree was boiled to make a dye. Paper dyed in it would not be eaten by insects, and would have been useful to the ninja for preserving important documents.

[Japanese Green Gentian]

[Chinese Cork Tree]