Studies in the Morphology and Life History of Anisogramma anomala

SUMMARYA morphological and cytological study of the life history of Anisogramma anomala which causes a cankering disease of commercial hazelnut, Corylus avellana, was undertaken. Mycelium colonizes the phloem forming a pressure cushion of pseudoparenchyma which eventually develops into a stroma. Perithecia form from primordia which are scattered throughout the hypostroma. The primordia consist of an “outer coil” of filamentous hyphal cells terminated by a nonfunctional trichogyne, surrounding an “inner coil” of more isodiametric ascogonial cells. The centrum arises from this inner coil as a loose clump of ascogenous cells which lack croziers. Asci arise from mononucleate cells of the ascogenous hyphae. The asci go through a typical meiosis followed by two successive mitotic divisions giving rise to eight unequally two-celled, hyaline ascospores. Spore dissemination occurs in response to hydration of both the ascocarp and individual asci. The pathology and histology of the host's response to infection are discussed.