Eucommia ulmoides Eucommia ulmoides Oliv. was first called rubber tree, because of this sticky substance in bark, Eucommia ulmoides Oliv. bark is the most sticky, and then it was gradually recorded in the Materia Medica. Eucommia ulmoides Oliv. is a very common tree in daily life. It is no different from other big trees in appearance. Its bark has a characteristic, that is, when the bark is torn apart, you will see that there is a layer of white sticky silk in the bark core, which is very sticky.