A Revision of the Schistidium Apocarpum Complex in Norway and Sweden

From extensive field studies, including the use of mixed stands, the Schistidium apocarpum complex, comprising the small-spored species of the genus, is found to be very rich in taxa in Scandinavia. The taxa are defined by a combination of gametophytic and sporophytic characters. The most important characters are found in the cell structure of the leaf lamina, the recurvature of the leaf margin, hair-point structure, urn shape, exothelial cell pattern, and in the peristome. Character states are classified as plesiotypic or apotypic. Structural reduction, particularly in the sporophyte, seems to be a major trend of evolution.

Thirty-one species, two subspecies and two varieties occur in Scandinavia. The taxa are placed in five informal groups. Aspects of the ecology and phytogeography of the Schistidium apocarpum complex and its taxa are studied. Distribution maps for Scandinavia and the northern hemisphere are provided for each taxon. The taxa are placed in well-known phytogeographical elements.