The seed bank of Lythrum salicaria L. was studied in wetlands of mid-continent North America where this Eurasian species is considered a nuisance. Recruitment under conditions chosen to promote high rates of germination did not exhaust the seed bank in a 1-cm deep layer of wetland soil in experimental flats. Emergence of seedlings from experimentally buried seed decreased linearly (P = 0.0001, R2 = 0.89) from 90% at the soil surface to 0% at 2 cm. In the wetlands studied, there were 410 000 L. salicaria seeds m-2 in the top 5 cm of soil; 37% of these were found below a depth of 2 cm. The implications of these results for the control of this species are discussed.