The occurrence of axillary antheridia in dioecious mosses

Abstract

Antheridia that are undoubtedly axillary occur in species of Bryum, Mnium and Aulacomnium. It is suggested that this is a primitive feature and that the typical moss antheridial head, with all the antheridia apparently terminal, has been derived from species with axillary antheridia, either by restriction of the antheridia to the axils of the uppermost bracts, as in the liverwort Haplomitrium blumei, or by the suppression of the upper bracts.