Peatlands are ecosystems that have a ground layer dominated by bryophytes. Bryophytes act as foundational species in both bogs and fens and largely control many ecosystem functions as well as form the majority of organic matter sequestered in many of these systems. Here, a key is presented to 65 bryophyte species that represent most of the species that occur commonly in northern and oceanic North American peatlands. Also, taxonomic comments, brief morphological descriptions, and ecological preferences for each species are given.