The pollination ecology of two species of Parkia (Mimosaceae) in southern Thailand

Abstract

Although the floral traits of Parkia conform to the bat-pollination syndrome, many visitors other than bats have been observed at their flowers. Some chiropterophilous plants are also pollinated by other animals; the syndrome is therefore best regarded as a hypothesis for which field observations and pollination experiments are required. The present study aimed, for the first time, to determine the breeding system of the economically important canopy trees, Parkia speciosa and P. timoriana, and to identify their pollinators. Pollination experiments carried out in Trang and Songkhla Provinces, in 28 trees of P. speciosa and four P. timoriana indicated that they are self incompatible. Open pollination resulted in the highest fruit set (average 60–67% of inflorescences per tree) although this was not significantly different from hand-crossed pollination (48–60%). Insect pollination resulted in fruit set in only 12% of P. speciosa inflorescences. Fruit bats, mainly Eonycteris spelaea, visit flowering plants continuously from dusk till after midnight. Nocturnal and diurnal insects (moths and stingless bees respectively) visit capitula, mostly at the nectar zone. Nectarivorous bats are the most effective pollinator for P. speciosa and P. timoriana. The fact that populations of E. spelaea appear to be declining throughout their distribution is therefore a matter of increasing concern.