Evolutionary Implications of Leaf Resin Pocket Patterns in the Tropical Tree Hymenaea (Caesalpinioideae: Leguminosae)

Abstract

ABSTRACT: Measurement of the size (volume), distribution, and density of resin pockets are compared in margin and center areas of leaves in 11 species (including six varieties of two widespread species) of Hymenaea. Resin composition and yield (mg/g leaf tissue) were analyzed by gas-liquid chromatography. Resin pocket patterns in certain species are highly distinctive; also a relationship seems to exist between patterns of closely related species, with variation having occurred in species or populations of widespread species which have radiated into different kinds of habitats. Thus these patterns may provide useful taxonomic characters, but we suggest that some of the patterns (and thus composition and yield of resin of different portions of the leaf) have evolved under selective pressures of herbivorous insects.