The morphology and cultural characteristics of Ophiostoma piceae were described on the basis of 22 strains from the CBS collection supplemented with 25 fresh isolates from Poland, mostly from necrotic parts of Quercus robur. The pleomorphism of anamorphs of the fungus is described in detail. The various cultural types could be reproduced by replicate transferance. The identity of the anamorph strains was confirmed using some strains that produced perithecia. It is concluded that cultures of O. piceae may be quite different in appearance, and that several names that are in current use should be regarded as synonyms. An emended description of the taxon is provided.