Polyporus squamosus Fr.

BASIDIOCARPS occur on trees, annual, very large, fleshy, usually single.



PILEUS at first circular, later reniform or fan-shaped, 5-60 cm diam, 0.5-5 cm thick, with a continuous, thin, slightly wavy, occasionally tucked up border. The outer surface of fresh basidiocarps is sticky, cream-coloured; in older specimens, it is buff and almost always covered with concentrically distributed brown to chestnut-coloured hulls.


STIPE lateral, rarely excentric, sometimes central, short, 3-10 x 2-6 cm, covered with usually reticular, whitish or brownish-flesh-coloured pores on the top; its bottom part is covered with a red-brown or black tementum.


HYMENOPHORE uniform, 1-3 cm thick, whitish or straw-coloured when fresh, then darkening and cork.

Tubes (t) at first short, resembling pits, later extending up to 5-10 mm, white or brownish-flesh-coloured.

Pores (po) very large, 1-2(-3) x 0.5-1.5 mm, irregular, angular, whitish when fresh, cream-coloured when dry.

Hyphae (h) colourless, wavy, slightly branched, septate, usually thick-walled, rarely thin-walled, 4-8(-15) µm, 1.5-4.5 µm thick.

BASIDIA (b) 40-60 x 7-9 µm, with 2-4 sterigmata, 6-8 µm long.

Basidiospores ellipsoidal, sharpened and slightly curved at the base, colourless, smooth, 10-14(-16) x 4-5(-6) µm, with one or a few oil droplets.

PLANT HOST AND DISTRIBUTION. Polyporus squamosus is a parasite of different species of deciduous trees (Domanski et al. 1967). It rarely affects coniferous trees.

This fungus mainly occurs in temperate regions of the world.

NOTES. Polyporus squamosus is a wound parasite. Its basidiocarp usually develops on thick branches and trunks of the higher tree parts.

Polyporus squamosus causes a white heart-rot of the tree tissues infected. The infected wood generally becomes much lighter and tends to split into irregular cubes (Brooks 1953).


Brooks F. T. 1953. Plant diseases. Geoffrey Cumberlege. Oxford University Press. London, New York, Toronto.

Domanski S., Orlos H., Skirgiello A. 1967. Grzyby (Mycota) III. Postawczaki (Basidiomycetes), bezblaszkowe (Aphyllophorales), zagwiowate II (Polyporaceae Pileatae), szczecinkowate II (Mucronoporaceae Pileatae), lakownicowate (Ganodermataceae), bondarcewowate (Bondarzewiaceae), boletkowate (Boletopsidaceae), ozorkowate (Fistulinaceae). Warszawa, 398 pp.