Abstract: Eucommia ulmoides Oliv. is a deciduous elm like tree, as an ornamental cultivated in China. Many works on the vegetative anatomy of the Eucommia had been carried out very early, but the floral development was seldom known. The present study was undertaken with a view to provide a description of the sporogenesis and gametophyte development of this plant. Flower buds in various stages of delopement and open flowers of the plant were collected from trees growing in the vicinity of Nanking and fixed in FAA. The material was imbedded in paraffin and sections, 8–10 μm in thickness were cut, stained either in Heidenhains iron-alum heamatoxylin or with safranin and crystal violet. In the first collection on 24th March, the sporogeneous cells did not round off or separated from each other. As the microspore mother cell arised from sporogeneus cell, the four lobes of each anther were fully enlarged. After the first reduction division of the microspore mother cell took place, no cell plate was laid down and the two daughter nuclei immediately took part in the second division. The arrangement of the tetrad in Eucommia is of tetrahedral type. The reduction division stage of microsporegenesis was found in material collected on 24th March. The pollination occurred at the end of March in 1954 at Nanking. The tapetal cells are uninucleate ories at first but through succeeding divisions, when the microspore mother cells are in synthesis, they become two- or four-nucleate. After the microspores have been separated, the tapetal cells get loose. A gradual diminution of cytoplasm proceeds simultaneously with the further growth of the pollen grains, and finally the contents are entirely used up. During pollination the nucleus of the microspore divided into two parts to form a large tube cell and a small generative cell. Then the pollen tubes stretched into the nucellus in the last two weeks of April. Meanwhile the generative cell has already been divided into two male nuclei. At this later stage, the tube nucleus was still in presence. But it is not the case in Ulmus (Shattuck, 1905). Two anatropus ovules arise from the inner surface of the ovary wall, and one of them aborted after fertilization. A single layer of integument arises from the chalazal end of the ovule by periclinal division. Parallal to formation of the integument a hypodermal cell of the nucellus is differentated as an archsporial cell. It is easily recognized by its large size and deeply staining characteristics. The hypodermal archesporial cell in the young nucellus divides to form a primary wall cell and a megaspore mother cell. Resulting from the successive divisions of the primary wall cell, a number of parietal cells situiate between the epidermal layer of the ovule and the megaspores. Therefore, the early development of nucellus belongs to Crassinuceltate type. But as the embryo sac enlarges the parietal cells aborte and thus the nucellus becomes simple nucellate. After megaspore mother cell forms linear tetrad of megaspores, the upper three degenerate progressively. Consequently, only the chalazai one develops into embryo-sac apparatus and thus monosporic type is conformed. The remaining megaspore undergoes two further divisions forming a typical eight nucleate megagametophyte. The mature embryo-sac, in general, consists of three antipodals, two polar nuclei, and three of the micropylar nuclei which are incorporated in cells to form the typical egg apparatus. And thus, the development of the megagametophyte of the species of Eucommia investigated indicates that this genus is of polygonium type somewhat differs from the Adoxa and Drusa types of the Ulmaceae in the Urticales.