There was very little similarity in the floristic composition of seed banks from the same or different vegetation types in different marshes: the average Sørensen's similarity index values ranged from 24 to 28%. The floristic composition of seed banks from different vegetation types within a given marsh was more similar: the average Sørensen's similarity index value was 41%. The results also suggested that allelopathic interactions in substrate samples with high amounts of organic matter resulted in either the inhibition of seed germination or the death of seedlings of several species.