24. Earth, Wood, Nectarous and Plateau Medications. Medications derived from earth include golden sand, yellow ochre, saltpetre, natron, sulphur, vitriol, chalcanthite, lichen and bitumen. Wood medications may be compounded from the roots, trunk, branches, bark, sap, leaves, föowers and fruits of specific trees. Nectarous medications are derived from grass, trees and animals Plateau medications are prepared from grass, stalks, leaves, nowers and fruit.