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Page number:697 
Remarks (public):Very close to H. lundellii, which can be looked upon as an ecological derivative of H. bombycinum. They are distinguished preferably by spore size. H. bombycinum is very variable in external morphology, esp. in the hymenial surface and the size of the fruitbody. The hymenium may be anything from completely smooth to very uneven. In microscopical detail it is much more uniform. There is a characteristic variation in the spore shape. Most of the spores are evenly ellipsoid but there is always a number of ovoid spores, i.e. the tangents to the central parts of the spores are not parallel but meet at a sharp angle. The proportion of such spores varies in a way that seems to be of taxonomical interest. The collections from Pinus bark look different and have been described as a taxon of their own, f. pinicola Lund., in Lund. & Nannf., Fung. exs. suet. n. 1031, 1941, where Corticium molle Karst. (non Fr.) and C. karstenii Bres., Ann. mycol. 9 p. 427, 1911, are reported as synonyms. This form has a much smoother hymenium than the specimens growing on deciduous wood and there is a layer of parallel hyphae next to the bark. This is usually not the case in fruitbodies from deciduous wood. The ellipsoid spore-form seems to be more dominant in f. pinicola. This form is no doubt very uniform and characteristic but the differences are small and can depend on the special morphology of the Pinus bark, thus experimental proofs are needed before it can be accepted as a taxon of its own. 
Description type:Non-original description 
Description:Hypochnicium bombycinum (Sommerf. ex Fr.) John Erikss., Symb. bot. Ups. 16:1 p. 101, 1958. - Thelephora bombycina Sommerf. ex Fr., Elench. fung. 1 p. 211, 1828. - Thelephora bombycina Sommerf., Fl. Lapp. suppl. p. 284, 1826. - Corticium bombycinum (Sommerf. ex Fr.) Bres., Att. Acad. Sci. Lett. Art. Agiati 3:3 p. 111, 1897. - Corticium oosporum Karst., Hedw. 29 p. 270, 1890. - Corticium granulatum (Bon.) Karst., Bidr. Finl. nat. folk 37 p. 244, 1882.
Fruitbody resupinate, effused, often becoming large (several dm2), adnate and separable only in pieces, varying in thickness, mostly 0,10,5 mm, but vigourously growing specimens may be considerably thicker (several mm), white, often hygrophaneous when young and wet, when old turning yellowish and at last pale ochraceous, hymenium smooth or tuberculate, sometimes projecting hyphae give it a hispid
or more or less hydnoid appearance, hymenium continuous, mature specimens when dried more or less cracked; margin usually fibrillose but varying with growth circumstances, sometimes fertile throughout.
Hyphal system monomitic; hyphae thin- to rather thickwalled, distinct, 3-5 µm wide, fibulate, richly branched from or close to clamps, subicular hyphae forming an open texture of more sparsely branched hyphae, next to the substrate more or less parallel, otherwise mainly descending; subhymenial hyphae thinner, forming a denser texture with predominantly vertical hyphae; all hyphae cyanophilous.
Cystidia none.
Basidia at first narrowly clavate, when mature more or less constricted and sinuous, 45-65 x 6-8 µm, normally with 4 sterigmata, which are conical and somewhat curved; numerous oildrops in the protoplasm.
Spores ellipsoid or ovoid, smooth, thickwalled, cyanophilous, non-amyloid, 9-11 x 6-8 µm.
Habitat. On all sorts of deciduous wood, mostly on fallen logs but also on stumps, standing trunks, dead hanging branches a.s.o. Less common on coniferous wood, but occurs on Pinus in a somewhat deviating form (see below). The biotopes are varying, but usually deciduous forests, parks a.s.o.
Distribution. Frequent species in practically all parts of N. Europe with the exception of the conifer forests of inner N. Scandinavia. In the northern coastal region (e.g. in the Alnus coast forest) and in the subalpine deciduous forest it is a common species.
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