Studies of fertility of Dicranum majus in two populations with contrasted sporophyte production

Abstract

Some populations of the dioicous moss Dicranum majus Sm. in southern Norway do not or only rarely produce sporophytes, while most populations in central Norway produce sporophytes frequently. Two populations of D. majus in spruce forest, one from southern Norway (without sporophytes) and one from central Norway (with many sporophytes) were investigated to find differences in sexual reproduction between them. The population in southern Norway had only a few perichaetia and neither dwarf males nor sporophytes, while perichaetia, males and sporophytes were abundant in the population from central Norway. Shoots with dwarf males formed perichaetia more often than shoots without males, and the proportion of fertilized archegonia increased with increasing numbers of males on the shoots.Genetic differences or some earlier environmental ‘disaster’ related to extreme drought or heavy pollution loads are discussed as possible explanations for the sparse sporophyte production in southern Norway. In order for sporophytes to be produced in the population in southern Norway, new males must be established from spores from outside.