A Contribution to the Pollen Morphology of Neotropical Lauraceae

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Abstract
The present study is a pollen-morphological investigation of 80 species belonging to 17 of the 22 known neotropical genera of Lauraceae. Observations were made with light and scanning electron microscopes. An ultrastructural study of the pollen wall of 11 genera was also undertaken by transmission electron microscopy. The pollen grains of most of the genera are easily identifiable by their sizes and by the number and organization of spinules. The pollen grains of all the species investigated are apolar, spheroidal, and inaperturate. The exine is very thin and coherent due to loosely or densely packed globular to variously shaped bodies. The surface of exine is scattered with pointed or blunt, monomorphic or dimorphic spinules. The spinules are made up of numerous tightly woven strands; their bases are encompassed by a thick, circular, cushionlike form. The intine was found to be the dominant layer of the pollen wall and to show varied composition and structural details. It is remarkable that a similar type of intine has been encountered in the inaperturate pollen grains belonging to such disparate genera as Canna, Heliconia, Hernandia, and Palmeria. The taxonomic implications of the palynological observations are discussed.