This section is from the book "Sub-Alpine Plants Or Flowers Of The Swiss Woods And Meadows", by H. Stuart Thompson. Also available from Amazon: Sub-Alpine Plants: Or, Flowers of the Swiss Woods and Meadows.
Flowers regular. Stamens numerous. Stigma sessile on the many-celled ovary. A small family of aquatic plants, with large handsome flowers and floating leaves. About 35 species growing in the waters of almost the whole globe.
Castalia alba (White Water-lily) and Nymphcea lutea, the Yellow Water-lily, are found in lakes and ponds in the lowlands of Switzerland, etc., and Nymphcea pumila Hoffm. is much less common in mountain lakes in Switzerland, Tyrol, Carinthia, and the Vosges. It is smaller than the Common Yellow Water-lily, with much smaller flowers, unguiculate petals, and oblong, slightly peltate leaves.