Fig. 4

Development of embryo in Cypripedium japonicum. a. Developing pro-embryo. b. First division in pro-embryonal cell followed by elongation of micropylar cell forming unequal size of two embryonal cells. c. Second transverse division in chalazal cell forming three celled pro-embryo (two chalazal, and a micropylar). d. Third division in chalazal cell forming four-celled linear pro-embryo. e. Five celled linear pro-embryo (micropylar cell divides in this stage forming two celled suspensor). f. Longitudinal division in chalazal cell of five celled embryo showing two juxtaposed cells. g–i. Pro-embryo forming early stage of globular pro-embryo (endosperm nucleus completely degenerates after this stage). j–k. Periclinal division in embryonic cell (except two basal suspensor cells) forming protoderm layer of embryo. l. Fully developed embryo covering whole inner space of the seed. Abbreviations: pem, pro-embryo pd., protoderm layer; s, suspensor; sc, seed coat. Scale bars: a-l = 20 μm