"[Plin. Nat. 25.34.] - CLYMENUS: GENTIAN: THIRTEEN REMEDIES.
Gentian was first discovered by Gentius, king of Illyria. It is a plant to be found everywhere, but that of Illyria is the finest. It has a leaf like that of the ash, but equal in size to a lettuce-leaf: the stem is tender, about the thickness of the thumb, hollow and empty, and covered with leaves at regular intervals. This stem is sometimes three cubits in length, and the root is flexible, swarthy, and inodorous. It is found in the greatest abundance in humid localities at the foot of the Alps. The root and juice are the parts of it that are used: the root is possessed of certain warming properties, but it should never be taken by women in a state of pregnancy.”
(The Natural History. Pliny the Elder. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855.)