Abstract:In order to understand the systematical significance of Geodorum recurvum in Orchidaceae, the development of both embryo sac and embryo were observed by using paraffin section method. The results showed that ovule primordium of G. recurvum developed slowly before blooming, and then developed quickly into “tree-like two-branch branching structure” after pollination, archesportial cells differentiated at the top of branches, and the embryo sac began to develop. The development of embryo sac belonged to polygonum type, ovule had two layers of integument cell. Archesportial cell developed into embryo sac mother cell by expansion and enlongation. The embryo sac mother cell formed linear tetrad by meiosis, and one functional megaspore at micropylar. Functional megaspore divided into 8-nucleu embryo sac by three times division successively. The developement of embryo had chenopodium type and asterad type. After double fertilization, the zygote divided into a basal cell and an apical cell by a transverse division. The basal cell formed cell group by division many times, and the cells formed suspensor cells situated through expansion and enlongation along different directions. The apical cell had two division type, one formed quinoa type embryo by transverse division, another did asters type embryo by longitudinal division. Therefore, it was suggested that the evolution of G. recurvum belonged to primitive in Orchidaceae.
