Annatto tree flowers open before dawn, when they are visited by large bees. Smaller bees also visit them in the morning. These insects harvest the abundant pollen from the flowers, which do not produce any nectar. The flowers fade around noon and the corolla drops off in late afternoon.
This tree has nectar-bearing glands on the branches, knots and flower and fruit stems. These glands are active on the branches when the leaves are very young. On the stems, they are active from the time flowering starts until the tree has finished producing fruit. The ants attracted by these sweet secretions protect the tree from herbivorous insects. Birds eat the seeds. Neither vines nor epiphytes grow on this tree.