AbstractThe life history ofEuryale feroxSalisb, observed in Akashi, Southwestern Japan, is described. Cleistogamous (CL) flowers appear from early July and precocious pollination occurs. Chasmogamous (CH) flowers are seen during a limited period between mid‐August and mid‐September. The abundance of CH flowers varies among populations and/or from year to year. Few insects visit CH flowers and self‐pollination occurs prior to anthesis. The number of seeds produced by CL flowers significantly exceeds that of CH flowers. Considering the shorter period of CH flower production and the lesser quantity of seed produced, the significance of CL flowers in the maintenance ofE. feroxpopulations must be considered greater than that of CH fl