Abstract: We observed floral organ differentiation, megasporogenesis, microsporogenesis and the embryogenetic process in Eupatorium adenophorum by the paraffin section method. The floral bud differentiated when the diameter of the anthodium was between 0 and 1.6-1.8 mm, and microspores, megaspores, microgametophytes and megagametophytes developed when the diameter of the anthodium was between 1.8-2.0 mm and 3.8-4.0 mm. Pollen mother cell meiosis mainly occurred when the diameter of the anthodium was between 2.3 and 3.5 mm. Simultaneous cytokine styles, secretory tapeta, 3-celled mature pollen grains, dicotylous-developed anther walls and the polygonum type of mature embryo sacs were detected. In addition, the mature ovule was anatropous, unitegmic and tenuinucellate. A biembryo was found during the embryonic development period.

Key words: Eupatorium adenophorum, Floral organ differentiation, Megasporogenesis, Microsporogenesis, Embryogenesis