Abstract: Pollen morphology of nine species in Koenigia L. from China was examined under light microscope (LM) and scanning electron microscope (SEM). The pollen grains are 7(-8)-zonocolpate， pantocolpate， or pantoporate in aperture， spheroidal in shape， 17.0-32.5 μm in diameter (including the length of spinules). The ornamentation of exine is prominently spinulose. Based on their features of apertures and exine sculpturing, the pollen grains can be divided into three types， i.e., Delicatulum-type， Forrestii-type and Koenigia-type. The Delicatulum-type is characterized by having 7(-8)-zonocolpate aperture, imperforate tectum and prominently spinulose exine ornamentation. Pollen grains of this type occur in one species， K. delicatula （Meisn.） Hara. The Forrestii-type is characterized by having 12-pantocolpate apertures, imperforate tectum and prominently spinulose exine ornamentation. Pollen grains of this type occur in two species， K. forrestii (Diels) Měsíek & Soják and K. nummularifolia (Meisn.) Měsíek & Soják. The Koenigia-type is characterized by having 15-, 20（-30）-pantoporate apertures, imperforate tectum and prominently spinulose exine ornamentation. Pollen grains of this type occur in six species，K. cyanandra (Diels) Měsíek & Soják，K. fertilis Maxim.，K. hubertii (Lingelsh.) Měsíek & Soják，K. islandica L., K. nepalensis D. Don and K. pilosa Maxim. The present results show that the pollen morphology in Koenigia is of important systematic value. The generic status of Koenigia is supported; Polygonum nummularifolium and P. forrestii may be better transferred to the genus Koenigia from Polygonum sect. Aconogonon Meisn., while P. cyanandrum, P. delicatulum, P. fertile, P. filicaule, P. hubertii, P. pilosum transferred to the genus Koenigia from Polygonum sect. Cephalophilon Meisn.

Key words: pollen morphology, Koenigia, Polygonaceae, China.