Floral biology of a primary rain forest palm, Astrocaryum mexicanum Liebm.

A detailed account of the changes in visitor numbers and behaviour, inflorescence phenology, and breeding systems is presented. Inflorescences open early in the morning (05.00 hours). Stigmas remain receptive for 15 h, while anther dehiscence occurs 20 h after inflorescence opening. Maximum pollen viability occurs the next day at 05.00 hours. This combination of features largely precludes self-pollination. Controlled pollinations show that apomixis and auto-pollination are absent, and indicate strong incompatibility. In contrast, cross-pollinations do not differ in fruit set from open-pollinated controls. The fruit set in inflorescences exposed to pollinators for different periods after opening (and later stopping pollinator activity by fumigation), indicates that pollination occurs soon after inflorescence opening.
The visitors comprise a numerous and diverse fauna (15 families; 34 species). Features such as pollen loads, abundance, behaviour, and diet patterns, segregate them into: herbivores and predators (Aves, Orthoplera), pollen thieves (Apidae), and true pollinators (most Coleoptera and Diptera). The elevation in inflorescence temperature during opening, and 24 h later, is discussed in relation to cantharophily.
Astrocaryum mexicanum is an example of a highly diverse pollination system in which many animals can coexist. It represents an important resource during the dry season, and provides food and space for refuge and mating. The genetic consequences of having a host of pollinators with different dispersal capabilities are explored.