The study was carried out at the savanna areas of the Caça e Pesca Itororó Club, Uberlândia, MG, from September 1997 to November 1998. In order to confirm the occurrence of sexual dimorphism, several procedures were undertaken on the supposed dimorphic flowers: pollen viability analysis, measurements of plant height and length of the inflorescence, and pollination experiments to assess the breeding system. Results of pollination treatments and pollen viability analysis revealed the dioecious character of the studied individuals. Sexual morphs were significantly different in their height (F=11.01; P<0.001) and inflorescence length (F=240.82; P<0.005), both being larger on pistillate individuals. Fruit formation was observed only in cross--pollinated treatments between pistillate and staminate individuals (except one case among 900 trials). The occurrence of fruits naturally formed on male phenotypes indicates that the evolutionary process towards dioecy on this species is still not concluded. Pollination is performed by Polistes wasps and Xylocopa and Exomalopsis bees.
Cabralea canjerana; dioecy; breeding system; savanna
