Studies of Paleozoic Fungi. Iv. Wood‐decaying Fungi in Callixylon Newberryi From the Upper Devonian

An extensive fungal infection is present in silicified specimens of Callixylon newberryi (Dawson) Elkins and Wieland from the Upper Devonian of Indiana. Fungi are represented by branched, septate filaments with both terminal and intercalary chlamydospores. Clamp connections were not observed. Tracheids of the secondary xylem, decayed in varying degrees, show erosion troughs, cavities, and extensive lysis of tracheid walls. The pattern of decay is most similar to modern‐day white rots, which are typically caused by basidiomycetes, while hyphal features are characteristic of either ascomycetes or basidiomycetes. The presence of wood decay coupled with a septate mycelium suggests the presence of higher fungi in the Devonian and indicates a more diverse Devonian mycoflora than has previously been recognized.