Aechmea pectinata: a hummingbird-dependent bromeliad with inconspicuous flowers from the rainforest in south-eastern Brazil

The pollination biology of Aechmea pectinata (Bromeliaceae) was studied in a submontane rainforest in southeastern Brazil. This species has a mainly clumped distribution and its aggregated individuals are likely to be clones. From October to January, during the flowering period, the distal third of its leaves becomes red. The inflorescence produces 1-15 flowers per day over a period of 20-25 d. The flowers are inconspicuous, greenish-white coloured, tubular shaped with a narrow opening, and the stigma is situated just above the anthers. Anthesis begins at 0400 h and flowers last for about 13 h. The highest nectar volume and sugar concentration occur between 0600 and 1000 h, and decrease throughout the day. Aechmea pectinata is self-incompatible and therefore pollinator-dependent. Hummingbirds are its main pollinators (about 90 % of the visits), visiting flowers mainly in the morning. There is a positive correlation between the number of hummingbird visits per inflorescence and the production of nectar, suggesting that the availability of this resource is important in attracting and maintaining visitors. The arrangement of the floral structures favours; pollen deposition on the bill of the hummingbirds. Flowers in clumps promote hummingbird territoriality, and a consequence is self-pollination in a broader sense (geitonogamy) as individuals in assemblages are genetically close. However, trap-lining and intruding hummingbirds promote cross-pollination. These observations suggest that successful fruit set of A. pectinata depends on both the spatial distribution of its individuals and the interactions among hummingbirds. (C) 2003 Annals of Botany Company.92573173