Although surveys along the stream reaches within Vicksburg National Military Park indicated the absence of actual vascular aquatic plants, 17 different families of riparian plants were identified. These species grow in the moist buffer areas found along the waterways and wet meadows in the park, and include whorled marshpennywort (Hydrocotyle verticillata) and swamp smartweed (Polygonum hydropiperoides).
Historically, the land now comprising Vicksburg National Military Park was an area of hardwood forest and backswamps surrounded by natural levees created by the ever-changing Mississippi River. As these swamps were isolated, the vegetation changed according to sedimentation rates, canopy cover, and use by both wildlife and humans. As the area was cleared, the terrain became drier and more exposd, relegating freshwater plants to the smaller streams and springs in the ravines and lower reaches of the park.