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Page number:62 
Remarks (internal):The species can be confused with Polyporus squamosus which also has scales on the pileus, though they are not agglutinated. P. squamosus normally has thicker and more robust basidiocarps. See Jahn (1980) for details.
Description type:Non-original description 
Description:Polyporus tuberaster Jacq.: Fr. Fig. 18 Syst. Mycol. 1:347, 1821. Boletus tuberaster Jacq., Collect. Bot. Suppl. pls. 8-9, 1796. Polyporus lentus Berk. in Smith, Engl. Flora 5:134, 1836. P. coronatus Rostk. in Sturm J. ed., Pilze Deutschl. 28:17, 1848. R floccipes Rostk., ibid. 28:25, 1848. R maculatus Berk., Hooker London J. Bot. 3:80, 1849. R tiliae Fr., Hymen. Europ. p. 528, 1874. P. forquignoni Quel. in Guillaud et al., Cat. Champ. Sud-Ouest p. 42, 1884. P. decurrens Underwood, Bull. Torrey Bot. Cl. 24:83, 1903. R helopus Pat. in Pat. & Har., Bull. Soc. Mycol. Fr. 20:63,1904. Grifola tuckahoe Güssow, Mycologia 11:109, 1919. Favolus trigonus Lloyd, Lloyd Mycol. Writ. 7:1332, 1924.
Basidiocarps annual, stipitate, solitary when growing on wood, often caespitose when growing on the ground; pileus fleshy when fresh, circular to semicircular or even fanshaped in compound basidiocarps, flat to depressed in the centre, up to 15 cm wide and 1.5 cm thick; upper surface whitish, ochraceous to pale yellowish-brown, covered with small, tan to dark brown, agglutinated scales especially towards the margin, in pale specimens the scales are not especially distinct, with age becoming more glabrous from the centre as the scales are partly glued to the surface; margin thin, mostly finely ciliate or lacerate, flat in fresh specimens, curved in dried specimens; pore surface white to pale tan, pores angular, often somewhat radially elongated, 1-2 mm long and 0.5-1 mm wide, dissepiments often lacerate or dentate, tube layer concolorous with the pore surface, up to 5 mm thick; context white, up to 10 mm thick, fleshy when fresh, drying rigid and brittle; stipe central to lateral, straight or curved at the base, up to 6 cm long and 1.5 cm thick, with decurrent pores, at the base with white hairs under which there is a thin, resinous cuticle which may extend a short distance above the tomentum, above that the stipe is white to ochraceous.
Sclerotium normally present in the ground, round to oval or irregular, heavy, up to 15 kg, but normally far less than that, fleshy and tough when fresh, shrinking considerably on drying and becoming hard and brittle, surface ochraceous to dark dirty brown, densely mixed with sand, stones and roots, often in considerable quantities so that it looks like soill that has been penetrated by mycelial strands and white aggregations of hyphae.
Hyphal system dimitic; generative hyphae with clamps, hyaline, thin-walled, 3-9 µm in diam; dark brown on the stipe and pilear surfaces, parallel and forming tufts of hairs that are slightly amyloid in young basidiocarps; skeleto-binding hyphae hyaline, thickwalled to solid, sparingly branched, up to 12 µm wide in the main stem; sclerotium mainly with skeleto-binding hyphae, in parts very finely branched and very thin, in most parts sparingly branched, thick-walled and variable in diameter, 3-10 µm wide, in some cases with apical swellings. Basidia clavate, 4-sterigmate, 25-40 x 6-10 µm, with a basal clamp. Basidiospores cylindric to oblong ellipsoid, 10-16 x 4.5-7 µm.
Cultural characteristics. See Nobles 1948, 1958, 1965; Stalpers 1978.
Substrata. On hardwoods or on the ground from a blackish sclerotium. When growing on wood, there is often a connection through the wood to an underground sclerotium. It has certainly been collected on Acer, Alnus, Betula, Carpinus, Fagus, Fraxinus, Quercus, and Salix; in Italy also once on Juniperus.
Distribution. Temperate zone in the northern hemisphere and Australia, also found in Costa Rica.
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