"[Plin. Nat. 25.31.] - THE CENTAURION LEPTON, OR LIBADION, KNOWN ALSO AS FEL TERRÆ: TWENTY-TWO REMEDIES.
There is another centaury also, with diminutive leaves, known by the additional name of “lepton.” By some persons it is called “libadion,” from the circumstance that it grows upon the borders of fountains. It is similar to origanum in appearance, except that the leaves are narrower and longer. The stem is angular, branchy, and a palm in height; the flower is like that of the lychnis, and the root is thin, and never used. It is in the juice that its medicinal properties are centred: it being gathered in the autumn, and the juice extracted from the leaves. Some persons cut up the stalks, and steep them for some eighteen days in water, and then extract the juice.
In Italy this kind of centaury is known as “gall of the earth,” from its extreme bitterness. The Gauls give it the name of “exacum;” from the circumstance that, taken in drink, it purges off all noxious substances by alvine evacuation.”
(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.)