During my studies of the Surinam specimens belonging to this genus my attention was drawn to the often wrong interpretation of several old species. To avoid future misidentifications it seems useful to give a short review of the American species that are known up till now. It is emphasized, however, that this paper does not have the pretension to be a monograph of the American species. For the greater part my study of the species was confined to the type material and the variability therefore is not known. However, this contribution may serve as a base for a future monograph of this interesting group. Attention is drawn to the fact that only older leaves of the plants should be studied, because the leaf apex of the younger leaves is in all species acute and the lamina may not have reached its definite form.