By looking at the environment of known habitats of the perennial aquatic plant Podostemum ceratophyllum Michx. (common name hornleaf riverweed), I carried out a spatial analysis to determine possible unknown locations where P. ceratophyllum might be growing. ArcGIS was used in conjunction with high-resolution imagery from 2016 to compare the known locations of P. ceratophyllum to additional areas that meet the environmental and landscape criteria for the plant’s growth. These criteria include abundant sunlight, rock outcrops, and rapidly moving water. Most of the known locations in Kentucky are on the Kentucky River, Green River, and the Red River. This work is in support of continuing efforts to document P. ceratophyllum and file their locations into the Kentucky rare plants database.