Postzygotic control of selfing in Hymenaea stigonocarpa (Leguminosae-Caesalpinioideae), a bat-pollinated tree of the Brazilian cerrados

The pollination biology and breeding system of Hymenaea stigonocarpa, a common tree of the Brazilian cerrados, were investigated. The flowers have nocturnal anthesis, produce copious nectar, and are visited by at least four species of bats, including the specialized nectivorous Glossophaga soricina and the less specialized frugivores Platyrhinus lineatus and Carollia perspicillata. Controlled hand-pollination results indicate the species is basically allogamous. Almost all selfed flowers abscised within 7-8 d, but rejection was due to a postzygotic mechanism, since self-pollen tubes grew to the ovary and penetrated ovules with equal facility to cross tubes, and self ed ovules at 5 d contained a zygote with endosperm nuclei. The causes of selfed pistil abscission were not established, but selfed ovules were smaller than crossed ones at every stage over the first 5 d postpollination, indicating an early recognition or differential development of selfed ovules.