loosely felted, red-brown mass of hyphæ, which has been used for tinder and as a styptic (“Fungus chirurgorum”). _P. igniarius_ has a harder, dark-brown, more rounded fruit-body; it grows in a similar manner, but especially attacks Oaks, Poplars, and Plum-trees, the wood of which becomes rotten, and is called touchwood. _P. pini_ (_Trametes pini_), (Fig. 170), a parasite on the stems of _Pinus_, causes a kind of “red-rot” in the stem. _P. sulphureus_ has a soft, cheesy, yellow fruit-body; it produces “rot” in Oaks and Apple-trees. _P. officinalis_, Larch-fungus (“Fungus Laricis” in Pharmocopœia), grows on Larch-trees in the south-east of Europe. _P. versicolor_ has thin, semicircular fruit-bodies, with zones of various colours on the upper side; it is one of the most frequent species on tree-stems. _P. frondosus_ grows on soil in woods, and consists of numerous aggregated fruit-bodies, which become very large and fleshy. This species is edible. _P. perennis_ also grows on the soil in woods; it is very leathery, with central stalk, and has concentric zones on the upper surface of the fruit-body. _P. vaporarius_ destroys the wood of living Pines (_Pinus silvestris_) and Firs (_Picea excelsa_), causing it to become red-brown; in timber this Fungus causes “red-strip” followed by a “dry-rot.” _P. squamosus_ destroys many Walnut-trees, and is also very destructive to Limes and Elms. _P. fulvus_ causes a “white-rot” in _Abies alba_. [Illustration: FIG. 168.--Section of stem of a Beech attacked by _P. fomentarius_: _a_ non-attacked parts of the stem; _b_ the furrows where the mycelium has reached the bark, and where the thick mycelium-strands reach the exterior (⅙th of the nat. size).] [Illustration: FIG. 169.--Base of a Fir-tree, with a number of fruit-bodies of _Heterobasidion annosum_ just beneath the surface of the soil, indicated by the dotted line (¼th nat. size).] [Illustration: FIG. 170.--A fully developed fruit-body of _Polyporus pini_ (_Trametes pini_), lateral view (nat. size).] _Heterobasidion annosum_ (_Polyporus annosus_, _Trametes radiciperda_, Fig. 169) is characterized by its _Aspergillus_-like conidiophores. It is a parasite on the Pine, Fir, Birch, Beech, etc., and is the chief cause of a root-disease (red-rot) in Pines and Firs; the fruit-bodies develope a large number of basidiospores; they may be very large and are found just beneath the surface of the soil (on living or dead roots), and exposed to the air (on felled stems and roots, in Scandinavia).