This county atlas of Minnesota mosses shows the distribution of 343 species and 15 varieties authenticated for the State. All county records are based on specimens examined and verified by the author and deposited in either the author's personal herbarium, in the herbarium at the Science Museum of Minnesota, in MIN (The University of Minnesota Herbarium, St. Paul) or in DUL (The University of Minnesota Herbarium, Duluth). No unsubstantiated literature reports have been listed. For updates of the database, and possible future editions of the Atlas, the author would appreciate any information on additional county records based on collections that could be made available for loan and annotation.

Detailed taxonomic treatments for a Minnesota Moss Flora are being prepared, starting with Sphagnum, and will significantly alter the tally and composition of some families, such as the Amblystegiaceae, Brachytheciaceae, and Bryaceae, when the vouchers are more critically studied, compared with well represented material from other North American localities.

The nomenclature used is based on that of Anderson et al. (1990) for the mosses, and Anderson (1990) for Sphagnum. The taxonomic scheme presented in the Higher Taxa List is derived from Crum & Anderson (1989) and Crosby & Magill (1981).

Seventy-one of Minnesota's 87 counties have some moss record, the northernmost counties suggesting the highest diversity or best coverage. The map (at right) clearly indicates substantial under-collecting in some regions of the State, for example the counties immediately west and northwest of the Metro area, such as Todd, Wadena, Crow Wing, Morrison, Benton, Mille Lacs, Kanabec, and Wright, and also suggests poor coverage for numerous southwestern and western counties. As several cases indicate, the effect of single studies or intensive surveys of a small area, such as a State Park, can dramatically increase the number of records: Pine County from 18 to 111 species, Aitkin from 17 to 89, and Yellow Medicine from 45 to 67. For these reasons it is not yet possible to analyze the Minnesota distribution patterns for individual species, or to classify these different patterns in a meaningful way. An attempt has been made, however, to reflect at least the world-distribution affinity of Minnesota mosses so far listed.

The 358 species and varieties of mosses presently substantiated for the State of Minnesota compare as follows with the numbers listed for neighboring states and provinces: Ontario 490 species (Ireland & Ley 1992), Wisconsin 380 (Bowers & Freckmann, 1979), Iowa 272 (Conard 1956), North Dakota 106 (Ikenberry 1932), and Manitoba 267 (Bird 1973). There are 333 species tallied for the Great Plains, as defined by Churchill (1976).

The 15 varieties and 343 species of mosses recorded here for Minnesota belong to 139 genera and 45 families, compared with 109 varieties, 1329 species, 312 genera, and 72 families for the entire North American moss flora north of Mexico (Anderson et al. 1990). Some families are represented by a single species, such as the Andreaeaceae, Archidiaceae, Bruchiaceae, Bryoxiphiaceae, Buxbaumiaceae, Catoscopiaceae, Encalyptaceae, Ephemeraceae, Fabroniaceae, Hedwigiaceae, Schistostegaceae, Sematophyllaceae, and Tetraphidaceae, and 71 of the 139 genera include only one species for the State. Other genera have a substantial number of species, such as Sphagnum (33 species), Brachythecium (14) and Dicranum (11).

It is hoped that this publication will stimulate additional surveys in neglected counties, become the basis for the development of a list of rare and threatened species, and further improve the phytogeographic analysis of the moss flora of the State of Minnesota.