The Asteraceae have a high diversity of reproductive mechanisms, as shown by studies conducted mainly with species from temperate regions. Aiming to contribute knowledge on the reproduction of tropical species, we compared the floral biology and breeding systems of the co-occurring species Adenostemma brasilianum, Bidens segetum, and Graziella intermedia, and additionally identified their pollinators. The study was conducted in a seasonal semideciduous forest fragment in southeastern Brazil. Florets opened in the early morning and were protandrous. On the first day of anthesis, secondary pollen presentation occurred during the staminate phase, mainly in the morning. On the same day, the pistillate phase began, being long in A. brasilianum and B. segetum (up to 4 days) and short in G. intermedia (1 day). Pollen viability was high in all three species, except for two G. intermedia individuals which showed male sterility, thus characterizing a gynodioecious population. Self-compatibility was observed in A. brasilianum and self-incompatibility in B. segetum. In G. intermedia, besides sexual reproduction, apomixis was also observed. This is the first report of apomixis in the genus Graziella. Although the studied species show distinct reproductive mechanisms, all of them benefitted from cross-pollination, which was mostly done by butterflies.
