A recent overview of Salvinia finds from archaeobotanical literature by Out (2010), which also includes the finds in the present study, shows that Schokkerhaven is the most northern location of mid-Holocene Salvinia finds. It is the only location outside the Rhine/Meuse river area. Formerly, finds of Salvinia were dated to the Atlantic (early-Neolithic) mainly based on Zandstra (1966). The overview by Out provides more finds that are dated in the transition from Atlantic to Sub-Boreal and shows the occurrence of Salvinia during the Sub-Boreal (late-Neolithic) period. This fits with the occurrence of an other thermophilous aquatic species, namely Trapa natans elsewhere in the Netherlands. Trapa was frequently recorded in the early Subboreal (archaeobotanical database RADAR; Van Haaster & Brinkkemper 1995; Behre 1970).