Endozoochorous dispersal of the invasive alien aquatic plant Ludwigia grandiflora subsp. hexapetala through waterfowl in Lake Biwa, Japan, is reported. Germination of seeds collected from the feces of waterfowl in Yabase, southern Lake Biwa proved them to be viable. It is necessary to be vigilant against the sudden appearance of L. grandiflora subsp. hexapetala in water systems where it is absent and to monitor its dispersal by waterfowl.
