B. K. Bakshi

Polyporus lignosus Klotzsch and its identity

Polyporus lignosus is often confused with P. zonalis . They are two distinct species. Besides other characters, P. lignosus is usually parasitic while P. zonalis is commonly saprophytic. The two fungi are distinguished by their cultural characters. While rhizomorphic strands develop in P. lignosus as in nature, such strands are absent in P. zonalis , both in nature and in culture. Further, P. lignosus , with its thin-walled hyphae with cross-walls, can be distinguished from P. zonalis , in which the hyphae are very thick-walled and contain no visible cross-walls. No hyphal fusions occur when P. lignosus and P. zonalis are paired in culture.

A re-examination of Fomes lignosus and Polyporus zonalis

Forms lignosus (Klotzsch) Bres. and Polyporus zonalis Berk., both occurring parasitically and saprophytically, are described from sporophores and cultures. F. lignosus is orange-red on the upper surface with orange-yellow margin and orange-red pore tubes fading towards the context. In P. zonalis the surface is pale to pinkish with white pore tubes. The presence of mucronate cystidia in the sporophore and of fibre hyphae and conidia in cultures distinguishes F. lignosus from P. zonalis in which they are absent. The latter, however, develops incrusted cystidia in the sporophore and clamped hyphae and acanthophyses in culture, all absent from F. lignosus.