Sphagnum compactum DC is rare in southern Illinois with five known locations some 400 km south of sites in northern Illinois. We examined habitat preferences of this species in southern Illinois, where it occurs exclusively on shaded, north-facing sandstone cliff faces and canyons, all just south of the maximum extent of Illinoian glaciation. We consider these populations to be long-lived and perhaps represent isolated relict occurrences of the species. We also report Sphagnum henryense Warnst. new to the area.