Using light and scanning electron microscopy morphological studies of pollens were conducted to determine the sectional boundary and the relationships among eight species of section Zygophyllidium and its five related species of subg. Poinsettia. Pollen characters of 13 species were described, and their diagnostic keys were presented here. Based on the sculpturing patterns and the results of numerical analysis using 10 pollen characters 13 species were divided into four Pollen types: type I, having micro-reticulate shaped pollen (E. hexagona, E. lagunensis, E. hexagonoides and E. bilobata), type II, having reticulate shaped pollen (E. delicatula, E. extipulata, E. dentata, E. heterophylla, E. pulcherrima and E. cyathophora), type III, micro-reticulate shaped pollen with platten muri (E. lacera), and type IV, haying foveolate shaped pollen grains (E. chersonesa and E. eriantha). The results of pollen morphological studies suggest that the sect. Zygophyllidium should be delimited based on only four species, E. hexagona, E. lagunensis, E. hexagonoides and E. bilobata, E. delicatural and E. exstipulata of sect. Zygophyllidium must be transferred to subg. Poinsettia based on pollen morphology. E. eriantha and E. chersonesa having forveolate sculpturing pattern of pollen grains seem to be closely related with species from subg. Agaloma, and additional studies of these species are needed to determine the species relationships within Agaloma group.