Pollen Morphology of the American species of the subfamily Costoideae (Zingiberaceae)

A pollen-morphological study has been carried out on the American Costoideae, a subfamily of the Zingiberaceae ( Costus L., Dimerocostus O. Kuntze, and Monocostus K. Schum.). Four pollen types and two subtypes could be established on the basis of size, exine and apertural characters. These types are: Costus lima type, Costus warmingii type, Costus congestiflorus type and Dimerocostus type. It is assumed that the pollen grains of the genus Costus are pollen morphologically more advanced than the grains of Dimerocostus and Monocostus.