We investigated pollination biology and breeding systems in hybridizing populations of Pitcairnia albiflos and P. staminea; both species are endemic to rocky outcrops at Rio de Janeiro, Brazil. These species are morphologically distinct and easily recognized by floral color: white in P. albiflos and red in P. staminea. Putative hybrids show a large range of intermediate pink floral colors. The showy hermaphroditic flowers offer pollen and nectar that attract many visitors including bees, butterflies, hawk moths, and bats. Although the flowers of both parental species and hybrids open at night, only P. albiflos had other adaptations for nocturnal pollination. Flowering times overlapped during three consecutive years of observation. Bees visited both species and putative hybrids. Cross-pollinations were performed within and among parental species and hybrids in a greenhouse using plants transplanted from the field. Pitcairnia staminea and hybrids are self-compatible and could be spontaneously self-pollinated, whereas P. albiflos, though self-compatible, needs pollinators' services for self-pollination. Facultative agamospermy was found in the parental species. Prezygotic and postzygotic reproductive barriers between these taxa were weak. Reciprocal hand-pollinations between parental species and with hybrids yielded high fruit sets with viable seeds. Evaluations of fruit set, seed set, seed germination, and pollen viability were undertaken to compare the fitness of the hybrids relative to their parents. The hybrids showed equivalent fitness, except for lower pollen viability. Some conservation implications are noted.

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The pollination biology of Aechmea pectinata (Bromeliaceae) was studied in a submontane rainforest in south-eastern 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.

Bromelia antiacantha flowered from December to February and during this period the central leaves and bracts displayed a bright red colour. The inflorescence bears 150-350 flowers, with 10-35 flowers opening per day over 4-5 days. The flowers are dark magenta coloured with white margins, tubular-shaped with a wide opening, and their stigma is situated below the anthers. Anthesis began around 4:00 h and flowers lasted approximately 15 h. The highest nectar volume and sugar concentration occurred between 4:00-6:00 h; after this period, both decreased throughout the day. B. antiacantha is partially self-incompatible, non-autogamous, and therefore, pollinator dependent. The hummingbirds Thalurania glaucopis, Amazilia fimbriata, and Ramphodon naevius were its most frequent pollinators (55% of the visits), visiting flowers mainly in the afternoon. The scattered distribution of B. antiacantha promoted trap-lining behaviour of the hummingbirds, which favoured fruit set through xenogamy. Corolla colour, wide flower opening, sweet odour and concentrated nectar early in the day favoured bee visitation. Of the 38 % of bee visits, 96% were made by Bombus morio, mainly in the morning and their behaviour promoted self-pollination. The bee Trigona spinipes frequently acted as a pollen and nectar thief early in the morning, excluding most of the hummingbirds. Bromelia antiacantha has ornithophilous and melittophilous features, and despite being pollinated by two kinds of agents, its reproductive success depends on a given set of circumstances.

Armases angustipes (Grapsidae) crabs were recorded on 31.5 percent of Aechmea pectinata inflorescences, a common ornithofilous bromeliad in rain forests of southeastern Brazil. Crabs foraged mainly in the morning and used newly opened flowers, usually damaging the corolla, consuming the stamens and stigma, and interfering with hummingbird visits. This florivory may reduce the reproductive success of A. pectinata, both directly through consumption of flowers and indirectly by reducing pollinator visits.