Pollen morphology of the lianescent species of the genus croton (euphorbiaceae)

Abstract

The pollen morphology of lianescent species of the genus Croton L. was analysed with regard to the size, number of apertures, shape and ornamentation of the exine. The pollen grains are apolar, atreme and spheroidal. They vary from medium to very large in size with croton- and reticulate pattern with supramural elements (clavae). The species are divided into two groups: (1) exine ornamentation with psilate sexine elements (C. grazielae) and (2) exine ornamentation with striate elements (remaining species). The latter group can be subdivided according to the formation or not of a croton-pattern by the sexine elements and by its ornamentation. © 1996 Taylor & Francis Group, LLC.