Common reed, Phragmites australis, has long been a component of Northern Plains wetlands, but impending invasion by the non-native P. australis haplotype M may displace native haplotypes in the future. To increase understanding of historical Phragmites occurrence, we developed a geographic information system (GIS) protocol to improve the georeferencing of specimens from South Dakota herbaria, and mapped the distribution of Phragmites relative to geology, physiographic regions, and water bodies. There were 91 Phragmites herbarium specimens from South Dakota and adjacent Wyoming. Phragmites collections occurred in nearly all physiographic regions of the state, with concentrations occurring in the Prairie Coteau of eastern South Dakota and the periphery of the Black Hills in western South Dakota. GIS analysis showed that the Black Hills Phragmitescollection sites occurred in the “Red Valley” overlying the Spearfish bedrock formation. Phragmites usually occurred on wetlands or lakes in eastern South Dakota; Phragmites in unglaciated western South Dakota usually occurred on creeks and stock dams. There was no evidence of a recent increase in Phragmites collections. Because native Phragmites probably occurs throughout South Dakota, weed control practitioners should verify that Phragmites stands are of the non-native haplotype before implementing control measures
