Abstract: Pollen grains of six species in Thunbergia (subfamily Thunbergioideae), and of one species each in Staurogyne (subfamily Nelsonioideae) and Acanthus (subfamily Acanthoideae) in the Acanthaceae from China were examined under SEM. Pollen grains in Thunbergia are spheroidal, with the apertures being spiral and the exine ornamentation being psilate, granulate or rarely baculate. This pollen type is very special in this family and has been considered to represent a primitive condition. Pollen grains in Staurogyne are spheroidal, 3-colporate, with the exine ornamentation being psilate. Pollen grains in Acanthus are prolate, 3-colpate, with the exine ornamentation being finely reticulate or microperforate. Pollen morphological characteristics support the traditional placement of these three genera into three different subfamilies in the Acanthaceae.

Key words: Thunbergioideae, Nelsonioideae, Acanthoideae