The sectional subdivision of the North American Plagiochila is largely based on Schusters' comprehensive treatments of the genus. Here we summarize the results of recent morphological, molecular, and chemical work and present an updated section and species list. Internal Transcribed Spacer sequences of nuclear ribosomal DNA are used to clarify the sectional position of the Western Holarctic endemic Plagiochila austinii (member of the Asian sect. Trabeculatae) and to confirm the recently proposed synonymy of Plagiochila sciophila and P. euryphyllon. North American Plagiochila are subdivided into the sects. Arrectae, Cucullatae, Peculiares, Plagiochila, Rutilantes, Trabeculatae, and Vagae.