A phylogenetic arrangement of the 130 liverwort genera, comprising 582 species, that occur in North America north of Mexico is followed by an alphabetical synopsis of genera, species, subspecies, and varieties currently recognized. The treatment of each taxon includes pertinent synonyms, excluded names, and explanatory comments regarding currently accepted changes in taxon names and authors. Such updating has required making nine new combinations, as follows: Fuscocephaloziopsis connivens (Dicks.) Vá?a & L. Söderstr. var. bifida (R. M. Schust.) Stotler & Crand.-Stotl., comb. nov.; F. connivens (Dicks.) Vá?a & L. Söderstr. var. compacta (Warnst.) Stotler & Crand.-Stotl., comb. nov.; F. pleniceps (Austin) Lindb. var. sphagnorum (C. Massal.) Stotler & Crand.-Stotl., comb. nov.; Isopaches bicrenatus (Schmidel ex Hoffm.) H. Buch var. immersus (R.M. Schust. & Damsh.) Stotler & Crand.-Stotl., comb. nov.; Mesoptychia badensis (Gottsche ex Rabenh.) L. Söderstr. & Vá?a var. apiculata (R. M. Schust.) Stotler & Crand.-Stotl., comb. nov.; Neoorthocaulis hyperboreus (R. M. Schust.) L. Söderstr., De Roo & Hedd. subsp. helophilus (R. M. Schust.) Stotler & Crand.-Stotl., comb. nov.; Schistochilopsis grandiretis (Lindb. ex Kaal.) Konstant. subsp. proteidea (Arnell) Stotler & Crand.-Stotl., comb. nov.; Tritomaria capitata (Hook.) Stotler & Crand.-Stotl., comb. nov.; T. laxa (Lindb.) Stotler & Crand.-Stotl., comb. nov. The basionym citations for these new combinations can be found in the text treatments of these taxa. Thirty-four new heterotypic synonyms, distributed among 27 accepted taxa, have been proposed, primarily as a consequence of nomenclatural updating (see Appendix 1 for a list). Type species are indicated for all genera and basionyms are included, where appropriate. Distributional data, based primarily on literature reports, are also provided for each infrageneric taxon.

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