Abstract: In this paper, the embryo and integuments development of Cypripedium macranthos, an endangered species in orchidaceae were studied. The anatomical features during embryo development of this species were observed under a Nikon bright field microscope in paraffin-section method. Different from that of some tropical orchids, after fertilization, the inner integument of this species remains during the whole process of seed development and a layer of impermeable endothelium is formed. It encloses the embryo tightly and possibly prevents water and nutrition from entering the embryo, thus preventing mature seeds from germinating in vitro.

Key words: Orchidaceae, Cypripedium macranthos Sw., embryo, integument, development