The ontogeny of the antheriduim in some Leptosporangiate ferns with particular reference to the funnel-shaped wall

Abstract

An account of the ontogeny of the antheridium including some cytological details is given for some species of the Blechnaceae and Polypodiaoeae and for Polyphlebium venosum (R. Br.) Copeland, a member of the Hymenophyllaceae. In the species of Blechnaceae and Polypodiaceae which were examined the antheridium consists of three wall cells a discoid or columnar basal cell, a ring cell, and a cap cell-enclosing the androgonial tissue. The ring cell and cap cell are delimited by a wall which is laid down in the shape of a funnel. In Polyphlebium the antheridial wall typically consist's of four cells - a lower and an upper ring cell, a cap cell, and an operculum. Each ring cell is produced in a straightforward manner by a funnel-shaped wall. Davie's postulation concerning the development of the antheridium by a series of transverse walls and upward and downward expansion of the androgonial cell, giving the appearance of funnel-shaped walls and ring cells, has been included in text-books by Smith (1955) and Foster and Gifford (1959). This hypothesis is questioned, and an explanation of what is considered to be the true method of development of the funnel-shaped walls and ring cells in the fern antheridium is given. Anomalous antheridia of Blechnufm cartilagineum Sw., in which the androgonial tissue is flattened and abortive, form a deep cap cell and a ring cell separated by a funnel-shaped wall, although no expansion of the central androgonial cell takes place. The unusual method by which the pedicel and antheridial initial cell form from a cell of the filamentous prothallus in Polyphlebium is described.