AM ADOU, a name given to polyporus igniarius and P. fomentarius, fungi of the tribe or division hymenomycetes, and formerly included in the genus boletus. They grow upon old trees in Britain, and on the continent of Europe. The pileus is completely blended with the hymenium, which is pierced with thin-sided, rather angular, tubular, vertical passages—the whole fungus thus appearing as a leathery or fleshy mass; the under side of which is pierced by deep pores. P. igniarius is called hard A., or touchwood. P. fomentarius is called soft A., or German tinder. They are used as styptics for stanching slight wounds; and when steel and flint were in general use for striking fire, were much employed as tinder, being prepared for this purpose by boiling in solution of niter. The soft A. is used for making small surgical pads, for which its elasticity peculiarly fits it. P. fomentarius, or a very similar species, is found in India, and used there as in Europe.
It is also employed by the Laplanders and others for moxa (q.v.). It is sometimes made into razor-strops, and this use is likewise made of P. betulinus.—P. officinalis, the agaricon of Dioscorides, which grows upon larch-trees in the s. of Europe, is a drastic purgative, now rarely employed. P. suareolens, which grows upon the stems of willows, and is easily recognized by it anise-like smell, was formerly employed in medicine, in cases of consumption, under the name of fungus salicis. All these species are very similar in appearance. Another species of the same genus, P. destructor, is one of the fungi known by the name of DRY ROT (q.v.).—The remarkably light wood of lternarulia guianensis, a shrub of the natural order (q.v.), is readily kindled by flint and steel, and is used in Guiana as amadou.