Seed fall from the parental plant and subsequent dispersal by tidal water flow were investigated in Aeschynomene virginica (sensitive joint-vetch) in order to understand how these processes may affect local population regeneration and inter-population seed exchange. Local seed fall was estimated using seed traps around four isolated plants. Plots enclosed on all four sides by mesh fences were compared to plots with the streamside open to examine seed dispersal by water flotation. Seed flotation times and stream flow rates were then used to estimate the potential for water dispersal of seeds after they have fallen to the soil. Ninety-four percent of all seeds fell within 0.5 m of maternal plants, with an exponential decrease in dispersed seeds with distance from the base of parental plants. More seeds left open plots than completely enclosed plots, but there was no difference between the number of seeds leaving plots that had standing vegetation and those without vegetation. At least 50% of the seeds placed in water remained floating after 28.4 hours, and 5% remained floating after 81.8 hours. Water flow rates in wetlands where A. virginica occurs naturally may carry seeds over 2600 m from the maternal plant, representing a significant potential for water dispersal of seeds in this species. Seed movement out of patches may impact population dynamics of the patch from which the seeds leave. Dispersing seeds cannot contribute to the population in that patch the following season. Seed dispersal may also represent an important mechanism for a species such as A. virginica, which specializes in open, newly created habitats, to find and colonize new habitat patches.