The Bizarre Inflorescence of Norantea brasiliensis (Marcgraviaceae): Visits of Hovering and Perching Birds1

Abstract

AbstractThe pollination biology of Norantea brasiliensis (Marcgraviaceae) was studied in the rain forest of southeastern Brazil. This plant presents bizarre, brush‐type racemous inflorescences bearing numerous flowers and extrafloral cup‐shaped nectaries. Flower anthesis is diurnal, nectar production is continuous and copious, and the sticky pollen is readily removed by visitors during the first morning hours. The ruby‐coloured inflorescences were visited by eight species of hummingbirds (Trochilidae), and 10 species of passerine birds (three Coerebidae and seven Thraupidae). Hummingbirds hovered while probing for nectar and touched flowers occasionally, whereas passerine birds perched and made contact with flowers habitually. Due to differences in flower‐visiting and general foraging behaviour, perching birds act as better pollen vectors than hovering birds. The inflorescence of Norantea brasiliensis seems well fitted for pollination by passerine birds, and the hexose‐dominated nectar supports this idea. Pollination syndrome trends within Marcgraviaceae may stem from insect‐pollinated, condensed and spike‐like inflorescences which would give rise to bird‐pollinated, brush‐type inflorescences. From the same basic condensed inflorescence, bat‐pollinated umbelliform inflorescence may be derived from bird‐pollinated, pendulous and corymb‐like inflorescences. These postulated inflorescence types are found among the extant species of Marcgraviaceae.