This is widespread in base-rich marshy sites across eastern North America, but is less common on the southeastern Coastal Plain. See notes under georgianus and hattorianus; further study of some colls. is needed for reliable separation of records. FNA 23 states: "Scirpus atrovirens occasionally hybridizes with S. georgianus, S. hattorianus, S. pallidus, and S. polyphyllus".