Valsaria insitiva was studied in culture. Ascospores germinated on agar and on host bark by forming yeast-like cells that reproduced by budding or from percurrently proliferating sporogenous loci. Yeast-like cells gave rise to mycelial colonies that formed oval to elongate conidia from lateral, percurrently proliferating loci. Hyphal cells sometimes disarticulated to form arthrospore-like cells. Eventually, colonies produced multiloculate pycnidial conidio? mata which contained phialidic conidiogenous cells that proliferated to form periclinally thickened collarettes, or annellations, or sometimes underwent large proliferations which increased greatly the cell lengths. Conidia from conidiomata did not germinate. Valsaria insitiva (Tode:Fr.) Ces. & de Not. was studied in culture by Weh? meyer (1923), who reported that germinating ascospores produced colonies with hyphae fragmenting in an oidia-like fashion, and eventually gave rise to labyrinthiform pycnidia. The pycnidia were lined with ten-pin-shaped conidi? ogenous cells which produced oval, hyaline, one-celled spores. Wehmeyer placed the pycnidial anamorph in the form-genus Cytosporella. Saccardo (1882) described V. insitiva as having the pycnidial state Coniothyrium insitivum Sacc. (Saccardo, 1884), and described it as producing olivaceous conidia. These were of a larger size than those described later by Wehmeyer. Recently, a fungus matching the description of V. insitiva was cultured. The fungus produced not only structures similar to those described by Wehmeyer (1923), but also a yeast-like state and an Exophiala-like state not previously associated with the genus Valsaria. The pycnidial state described by Saccardo (1882, 1884) was not produced. This paper reports the results of this study. Since V. insitiva appears to be a heterogeneous taxon (e.g., Wehmeyer, 1923) possibly composed of several different species, the teleomorph is also described to identify more clearly the fungus used in this study.