Abstract
A field study of the floral biology of two species of Nymphaea (Nymphaeaceae) wp.s made. N. rudgeana G.F.W. Meyer, a night flowering species, was studied around Manaus and Belém. It is visited by the scarab beetle Cyclocephala castanea Oliv. in the Manaus vicinity and by C. verticalis Burm. in the Belém vicinity. N. rudgeana is protogynous and cross-pollination is quite frequent. N. ampla (Salisb.) DC., a day flowering species, was studied near Salvador, Bahia. This species is visited by the bee species Trigona spinipes. N. ampla is not protogynous and is largely self-fertilized, although a small amount of cross-fertilization may occur through the activity of the Trígona bees.