The pollination of Bromelia antiacantha (Bromeliaceae) in southeastern Brazil: ornithophilous versus melittophilous features.

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.