Abstract:The pollinarium morphology of 12 species of Cynanchum Linn. were observed under light microscope (LM). Three types of pollinia (spheroidal, prolate and perprolate) and six types of retinaculum (oblong, square, near square, regular triangle and near triangle) were observed. This is important for the classification of Cynanchum otophyllum and supports the treatment of Cynanchum Sect. Vincetoxicum in Flora of China(Vol. 63). As the pollinarium in Cynanchum is saggy while that of Tylophora R. Br. is horizontal, it supports that Tylophora should be a unique group.