Development of the Ascostroma in Pleospora armeriae of the Pleospora herbarum Complex

Abstract

The ascostroma of P. armeriae arises by the proliferation of a short chain of swollen cells and enlarges by cleavage ef active cells within the resulting knot complex. Pseudo-paraphyses arise by the loosening of central cells, which elongate in a parallel arrangement. Ascogonial cells arise by the condensation and enlargement of the nuclei of certain favored cells which send out ascogenous hyphal branches, which in turn give rise to the binucleate ascus initials at their tips. No antheridia, cell fusions or transfers of nuclei were seen at this stage. The asci expand upwards between the pseudoparaphyses. Only a few fusion or meiotic figures were seen. Spore formation is described.