THE BIZARRE INFLORESCENCE OF NORANTEA-BRASILIENSIS (MARCGRAVIACEAE) -VISITS OF HOVERING AND PERCHING BIRDS

The 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, nect ar production is continuous and copious, and the sticky pollen is read ily removed by visitors during the first morning hours. The ruby-colou red inflorescences were visited by eight species of hummingbirds (Troc hilidae), and 10 species of passerine birds (three Coerebidae and seve n Thraupidae). Hummingbirds hovered while probing for nectar and touch ed flowers occasionally, whereas passerine birds perched and made cont act with flowers habitually. Due to differences in flower-visiting and general foraging behaviour, perching birds act as better pollen vecto rs than hovering birds. The inflorescence of Norantea brasiliensis see ms well fitted for pollination by passerine birds, and the hexose-domi nated nectar supports this idea. Pollination syndrome trends within Ma rcgraviaceae may stem from insect-pollinated, condensed and spike-like inflorescences which would give rise to bird-pollinated, brush-type i nflorescences. From the same basic condensed inflorescence, bat-pollin ated umbelliform inflorescence may be derived from bird-pollinated, pe ndulous and corymb-like inflorescences. These postulated inflorescence types are found among the extant species of Marcgraviaceae.