Green roofs are a maturing application of best management practices for

controlling urban stormwater runoff. The majority of green roofs are planted with

drought resistant, higher plant species, such as the genus Sedum. However, other plant

varieties, such as mosses, may be equally applicable. Residential roofs and natural

terrestrial communities were sampled in both Maryland and Tennessee to determine moss

community structure and species water composition. This served as a natural analog for

potential green roof moss communities. During sampling, 21 species of moss were

identified throughout the 37 total sites. The average percent moss cover and water

composition across all roof sites was 40.7% and 38.6%, respectively and across all

natural sites, 76.7% and 47.7%, respectively. Additional maximum water holding

capacity procedures were completed on sedum and 19 of the 21 sampled moss species to

assess their individual potential for stormwater absorption. Sedum species on average

held 166% of their biomass in water, while moss species held 732%. The results of this

study are used as a basis to propose moss species that will improve green roof

performance.