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• Stamen initiation and early development in male and female flowers are similar. • Staminodes in female flowers develop abnormally late with the anthers degenerating to different degrees. • Staminode morphology varies from staminiform, spoon-shaped, navicular, tongue-shaped to petaloid structures. • Anther wall formation is the basic type, simultaneous cytokinesis results in tetrahedral tetrads. The stamen is an extremely important reproductive organ in angiosperms. Androecia are the places where pollen is produced and show diversity in number and form; some are even reduced to staminodes or nectary structures in Ranunculales, but the development, morphology and structure of staminodes are completely unknown in Menispermaceae. In this study, the androecium development of Cocculus orbiculatus (L.) DC. was observed in detail for the first time under scanning electron microscopy and light microscopy. The results show that 1) stamen initiation and early development in male and female flowers are similar, while the staminodes in female flowers develop abnormally at later developmental stages, with the anthers degenerating to different degrees and becoming more or less flat structures; 2) in female flowers, the morphology and structures of staminodes are diverse: staminiform staminodes with tiny indehiscent anthers where 2-celled pollen grains or tetrads could be found in locules, or spoon-shaped, navicular, tongue-shaped and petaloid flat structures with an apex covered with secretions on the ventral surface; 3) in male flowers, the meiosis of the microspore mother cells occurs with simultaneous cytokinesis, the tetrads are tetrahedral, and the 2-celled pollen grains are tricolpate. In addition, the anther wall formation is the basic type. Compared to those of other groups in Ranunculales, the staminodes in Menispermaceae share some common characteristics with those of Lardizabalaceae, such as their position, number, size, morphology and degradation degree. [ABSTRACT FROM AUTHOR]