The spring and autumn seed bank in a Fraxinus caroliniana dominated floodplain swamp of the St. Johns River in Florida was examined. Soil cores were collected at 14 microsite types. The seed bank was dominated by the single species Ulmus americana in spring and Cephalanthus occidentaks in autumn. Mean density of seeds in both the top 5 cm of substrate and at 5-10 depth decreased significantly from spring to autumn, principally due to the germination of Ulmus americana seeds. The highest viable seed density was on stump microsites (611 seeds/m2 in spring and 0 seeds/m2 in autumn) and the lowest viable seed density was on logs (127 seeds/m2 in spring and 25 seeds/m2 in autumn). Seeds of most of the dominant tree species in the floodplain were absent from the seed bank.