Hortia brasiliana Vand. (Rutaceae) is a common shrub found in cerrado areas of Uberlândia, MG, Brazil. Individuals are 0.5 to 2.0 m high, with rose-coloured and coriaceous flowers, displayed in dense inflorescences. The anthesis occurs along the day or night and can take from 25 min. to 3 hours to complete, according to the temperature. The flower is protandrous and produces an average of 60 µl of nectar, with sugar concentrations ranging from 24 to 32%. The species is self-compatible. Flowers are visited by six Passeriform birds belonging to the Fringillidae, Thraupidae and Mimidae families, considered effective pollinators. This pollination type is new for cerrado vegetation. Birds were observed visiting the flowers to obtain nectar from 4:30 a.m. to 8:30 a.m., when they were sent away by Trigona spinipes bees (Apidae). In order to visit the plant, the birds use the inflorescence as a landing platform, probing 15 to 25 flowers per visit without flight incursion. The permanence period of a bird in a particular plant depended on the arrival of other individuals, and all bird species showed agonistic behaviour when other birds landed on the same plant. Pollination was carried out when the stigma got in contact with body parts in which sticky pollen was adhered to. Among the bees, Trigona spinipes was the most regular visitor, its activity taking place from 8:30 a.m. to 5 p.m. Bees remained in the same inflorescense for a long time performing selfing and geitonogamous pollination. Xylocopa aff. hirsutissima was less common than Trigona spinipes, but due to its behaviour on inflorescences, contacting the stigma and the anther, and its larger size as compared to Trigona, it was considered an additional pollinator. Other visitors (wasps, butterflies, flies, and ants) were considered nectar robbers, occasionally able to perform pollination.
Rutaceae; ornithophily; Passeriformes; cerrado
