Flower biology of four epiphytic Malesian Gesneriad

Floral traits, flowering events, nectar production and reproductive success of Aeschynanthus horsfieldii R. Br., A. pulcher (Blume) G. Don, A. longiflorus A. DC. and Agalmyla parasitica CB Clarke were observed for sympatric populations in the Cibodas area, Mount Gede-Pangrango, West Java. All traits were significantly different among the species, but were associated with a bird pollination syndrome. Many flowers of Aeschynanthus longiflorus and Agalmya parasitica failed to develop mature stigmas. Agalmyla parasitica flowers take a longer time to attract pollinators and receive pollen than the others and the filaments begin to bend earlier than the others. Aeschynanthus pulcher produces more nectar than the other species at the female phase, but the concentration was lower than in Aeschynanthus horsfieldii and Agalmyla parasitica. These seem to be correlated with the reproductive success of the respective species, with flowers of Aeschynanthus longiflorus and Agalmyla parasitica setting fewer fruit than the other two species. Flower traits and pollination shift are discussed in light of evidence that Aeschynanthus horsfieldii also attracts bumble bees (Bombus rucifes).