Floral Scents and Pollination in Neotropical Lecythidaceae

Abstract

Floral scent was collected with head-space adsorption and analysed by gas chromatography-mass spectrometry for 12 species of Neotropical Lecythidaceae in the genera Corythophora, Couratari, Couroupita, Eschweilera, Grias, Gust4via, and Lecythis. Most of the species were dominated by a single floral scent compound. Most of the compounds identified in this study have been previously reported in floral scents collected with head-space techniques from other plant families. However, several of the fatty acid derived esters of hexanol and cis-3-hexenol present in Lecythis persistens have been reported only in one or a few other plant families. No apparent correlations were found between amount and number of floral scent compounds produced on the one hand and pollinator reward, morphology, color, or size of flowers on the other hand. The fatty acid derivatives found in Grias suggest that beetles may be the pollinators whereas the floral scent compounds of all other species studied are consistent with bee pollination. The floral scents of the nectar-producing species Eschweilera coriacea and Couratari stellata contain, in contrast to the pollen-producing species, compounds that are highly attractive to male euglossine bees. This suggests that floral scent may play a role in directing male euglossine bees to those species of Lecythidaceae providing nectar as a pollinator reward. The combination of secondary and primary floral attractants interacting with pollinators probably accounts for much of the species diversity of this family in Neotropical forests.