Seedlings of Nymphaea coerulea, N. lotus and Nuphar luteum were examined for monocoty-ledonous and dicotyledonous characters. The cotyledonary formation could be interpreted either as a single bilobed structure or as two separate cotyledons. However, the presence of an operculum and the recognition of a coleoptile and mesocotyl similar to those of grasses and sedges gave grounds for including Nymphaeaceae in the monocotyledons. The form of the hypocotyl and radicle and the leaf-type supported a position, as a specialized family, in or close to the Helobiae.