The seed coat anatomy of representative species from all 10 Neotropical genera of Lecythidaceae subfamily Lecythidoideae was studied. Grias, with fruits as diaspores, has an unspecialized exotesta and a poorly differentiated seed coat. In contrast, species of Lecythidoideae with seeds as diaspores possess well-differentiated seed coats with diversified protective mechanisms. Modifications of the seed coat are probably adaptations for seed dispersal by different dispersal agents. Examples of these adaptations are the exotestal hairs of Couroupita guianensis, which possibly protect the embryos as they pass through the digestive tracts of peccaries; an extension of the seed coat into a wing in species of Cariniana and Couratari, which facilitate wind dispersal; the papillate exostestal cells of Allantoma lineata, which probably promote dispersal by water; the well-developed arils of species of Corythophora and Lecythis probably sought after by animals, which in turn disperse the seeds; and the sarcotesta of Eschweilera ovalifolia consumed by fish, which in turn disperse the seeds. We conclude that the highly diversified anatomy and morphology of the seed coat of the Lecythidoideae has evolved from relatively homogeneous ovules at least partially in response to abiotic and biotic dispersal agents.

Key words: Lecythidaceae, seed anatomy, seed dispersal, seed morphology