The reproductive phenology, pollination biology and reproductive system of Cambessedesia hilariana were studied in a population occurring on rocky outcrops at Vinhedo, São Paulo State, southeastern Brazil. This species presents a flowering peak between October and December with high daily flower production. Anthesis begins at 7:00 h with slow petal separation, followed by grouping of the reproductive elements in the inferior part of the flower. The only resource is pollen, which is collected by the bees through buzz pollination. The stigma is receptive and the pollen viable for up to 60 hours. Fruit-set under natural conditions (70%) is similar to that from hand crosses (74%), but higher than fruit-set from selfed flowers (12.5%). There was no indication that self incompatibility reactions are present during pollen tube growth. The main pollinators are Bombus morio, Centris sp., Centris cf. nitens, Euglossa cordata and Xylocopa sp. The most frequent visitor is Centris sp. (50.71%), but its visits resulted in lower fruit- and seed-set than those of the other bee species. High fruit- and seed-set in C. hilariana seem to be related to bee diversity, pollinator foraging behaviour at the flowers and ability to carry pollen, frequency throughout the flowering period, as well as to the reproductive system which favours xenogamy.
Cambessedesia; diversity and behaviour; floral biology; melittophily; reproductive success
