Yellowstone’s geothermally influenced plant communities contain species that must be able to tolerate a wide range of conditions. Although most of these species are widespread in range and occur at diverse elevations, not all of them are common. A unique grass of the geyser basins is Agrostis rossiae. This species is highly restricted in range, growing in “vapor dominated” sites in the thermal areas, such as crack systems, the walls of thermal springs, or geothermally influenced depressions. Together, the widespread species and the local endemic form an interesting plant community in the geothermal areas.