OBSERVATIONS ON FRUITING AND SEED-SET OF STRATIOTES-ALOIDES L IN THE NETHERLANDS

In order to obtain an impression of fruit and seed production in stand s of Stratiotes aloides L., 48 stands of this species in seven areas i n the Netherlands were studied in 1992 and 1993. In 35 of these stands fruits were found; most of these appeared to De parthenocarpic. In th e area of Giethoom (province of Overijssel), however, most of the stan ds had many fruits with ripe seeds. Seed production in the female plan ts appears to be dependent on the presence of male plants in the direc t surroundings. Even in the stands with high seed production vegetativ e recruitment from offsets and turions appears to be much more importa nt for the maintenance of the stand.