Anatomical observations were carried out with witches' brooms of Thujopsis dolabrata var. hondai and Thuja standishii caused by Blastospora betulae. In the witches' broom tissues, parenchyma cells were found occurring abundantly which accompanied with hyphae and haustoria among or within the cells. The aecia with many spermogonia were fomed on malformned tissues. Observations of the nuclear condition showed that the mycelia and aeciospores were binucleate, while spermatia were uninucleate. Therefore B. betulae on the spemogonial-aecial host may be dikaryotic except for a transitory monokaryotic phase in the spermogonial stage.

　Among the KOH negative species of polyporicolous Hypomyces and its anamorphs examined, H. corticiicola, H. sympodiophorus, and Cladobotryum longiramosum were recorded for the first time from Japan. The ascospores of H. corticiicola were mostly septate in nature, but aseptate in culture. Japanese H. sympodiophorus inhabited Stereum sp., as the previous records in North America and Europe. So far Cladobotryum longiramosum has only been reported from Cuba.

　Lysurus gardneri Berk., a phalloid fungus collected in the Tokyo Metropolitan area, Japan is described and illustrated. This is the second of L. gardneri from Japan.

　Taxonomy and mycorrhizal status of Japanese entlomatoid fungi associated with rosaceous and ulmaceous plants were studied. Entoloma saepium and E. clypeatum f. hybridum were newly recorded from Japan. Entolomatoid fungi were not ectomycorrhizal. Transmission electron microscopy of the mycorrhizas suggested destructive infection of the fungal hyphae to the root cells and their collapse near the tip of the stele.