ELSEVIER Aquatic Botany58 (1997) 89 98 Aquatic botany Pollination of Echinodorus grandiflorus (Alismataceae) Milene Faria Vieira ~, Nat~.lia A. de Souza Lima Departamento de Biologia Vegetal, Universidade Federal de Vi¢osa, 36571-000, Vi~osa, Minas Gerais, Brasif Accepted 8 April 1997 Abstract Studies on the pollination and breeding system of Echinodorus grand(florus (Chamisso and Schlechtendal) Micheli were carried out on two natural populations in Vi~osa, Minas Gerais State. southeastern Brazil. One population was formed by individuals of ssp. grandiflorus and the other by individuals of ssp. aureus (Fassett) Haynes and Holm-Nielsen. The flowering periods were within the rainy season. Flower anthesis occurred during the morning hours and flowers lasted ca. 8 h. E. grandiflorus ssp. grandiflorus is self-incompatible: few fruits, but many adventitious plantlets are produced at the inflorescences. E. grando%rus ssp. aureus is self-compatible; many fruits and few adventitious plantlets are formed. Bees are the main flower visitors. The bee Protodiscelis echinodori (Colletidae) presents oligolectic foraging behavior, i.e., collects pollen from a single plant species or a group of related plant species. © 1997 Elsevier Science B.V. Keywords." Bees; Breeding system; Echinodorus; Floral b o ogy; Oligolecty; Protodisceli.~ 1. Introduction The family Alismataceae is cosmopolitan and consists of I I genera and about 75 aquatic or semi-aquatic species, the majority occurring in the New World. The principal neotropic genera are Echinodorus with 26 species and Sagittaria. with about 25 species: in Brazil, this family is represented by 18 species of Echinodorus and six Sa~ittaria species (Haynes and Holm-Nielsen, 1994). With the exception of preliminary studies of Lima and Vieira (1994) on Echinodorus grand(17orus, no information is available on the relationship between neotropic species Corresponding author. 0304-3770/97/$17.00 © 1997 Elsevier Science B.V. All rights reserved. I'll S0304-3770(97)00019-3