Water-hyacinth (Eichhornia crassipes) does produce bisexual flowers with anthers (Male) and pistil (female) on the same plant.
However there is tristyly in this species, with three distinctly different style (narrowed part of the pistil) lengths occurring on different plants, though the short style length only occurs in South America. Tristyly is assumed to facilitate out-crossing over selfing, but it seems that Water-hyacinths self-fertilize quite well, possibly making the function of their tristyly obsolete.
Perhaps lack of pollinators or cold weather limits seed pod production in temperate climate ponds. Perhaps when seed pods do occur they are overlooked. The seed pods are about 1 cm. long. Overall it seems that vegetative propagation is much more common than sexual propagation with this species.