Abstract: Chang Shan, the subterranean portion of Dichroa febrifuga Lour. (family Hydrangeaceae), and Shu Chi, the leafy tops of the same plant, have been used in Chinese medicine more than two thousand years, but their antimalarial action has been scientifically proved and constituents investigated only in recent years. A brief account of their history, botanical source, plant habit, cultiva-tion and collection and a detailed description of their sensory, macroscopical and microscopical characters are given. The important diagnostic features of Chang Shan are:-vessels with long oblique end-plates having well-marked scalariform perforations and often containing tyloses; septate xylem-fibres; idioblasts containing bundles of acicular crystals embedded in mucilage; thick-walled pericyclic fibres; the deep-seated origin of the cork. A well-marked medullary sheath of thick-walled, lignified and pitted parenchyma occurs in the pith of both the stem and rhizome. The important diagnostic features of Shu Chi are:-thick-walled, warty, unicellular trichomes; paracytic (rubiaceous) stomata; epidermal cells with pitted anticlinal walls and finely striated cuticle; water-pores in the teeth of the leaf; idioblasts with bundles of acicular crystals em-bedded in mucilage; droplets of fixed oil in most of the cells of the leaf; thick-walled pericyclic fibers from the stem as well as deep-seated cork and characteristic vessels as seen in the subterranean organs. The significance of some of the microscopical findings as a further illustration of the connexion between anatomy and taxonomy is also discussed.