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Page number:453 
Remarks (public):The perennial, often dark coloured and very hard basidiocarp at the base of living trees, the strongly dextrinoid skeletal hyphae, and the often drop shaped spores are diagnostic. 
Description type:Non-original description 
Description:Perenniporia fraxinea (Bull.:Fr.) Ryvarden- Polyp. N. Europe, p.307, 1978. - Polyporus fraxineus Bull.: Fr., Syst. Mycol. 1:374, 1821. - Boletus fraxineus Bull., Herb. France 2: pl. 433, 1789.
Basidiocarps perennial, pileate, broadly attached, single or imbricate, often large, up to 12 cm wide, 16 cm long and 2-8 cm thick at the base, often triquetrous in section, woody when dry, more corky when fresh; pileus surface at first velutinate, but soon glabrous, slightly zonate, often with small warts or thin ridges, at first ochraceous, becoming unevenly dirty brown to grey, often with reddish spots, and finally grey to black with a very thin crust, margin rounded; pore surface cork or wood-coloured, pores 4-6 per mm; context tough-fibrous to punky, isabelline to cream or pale cork coloured, later becoming cinerous to pale brown towards the pileus surface, up to 3 cm thick at the base; tube layers stratified, pinkish-ochraceous to cork-coloured, up to 6 cm thick in old specimens.
Hyphal system dimitic; generative hyphae hyaline, thin-walled, rather variable in width, mostly 2-6 µm in diam, with clamps; skeletal hyphae dominating in the context, dextrinoid, straight to flexuous, only very rarely branched, 5-10 µm in diam (in KOH), in the trama narrower, unbranched to sparingly branched, 2.5-6 µm in diam; the crust in old specimens consisting of very intricately intertwined skeletal hyphae, straight or with dendroid branching or more twisted and partly strongly swollen, up to 15 µm wide in swollen parts, the whole glued together to a dense structure with a yellowish colour in thin sections.
Cystidia absent, fusoid cystidioles present, 20-27 x 6-7 µm.
Basidia clavate, 4-sterigmate, 15-23 x 8-10 µm, with a basal clamp.
Basidiospores subglobose to drop shaped, thick-walled with distinct germ pore, variably dextrinoid in Melzer's reagent, 6-8 x 5-6.5 µm.
Type of rot. Causes a white root and butt rot in living hardwoods.
Cultural characteristics. See Baxter 1925; Campbell 1938; Nobles 1948, 1958, 1965; Stalpers 1978.
Sexuality. Heterothallic and tetrapolar (Montgomery 1936).
Substrata. On living and dead hardwoods, especially Fraxinus, but in Europe also collected on Aesculus, Castanea, Celtis, Eucalyptus, Fagus, Fraxinus, Gymnocladus, Juglans, Olea, Malus, Platanus, Populus, Prunus, Robinia, Quercus, Salix, and Ulmus.
Distribution. Widespread in Central and Southern Europe, Great Britain and north to Southern Sweden. Circumpolar and common in Eastern United States and Eastern Canada.
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