Gametophyte and embryonic ontogeny: understanding the reproductive calendar of Cypripedium japonicum Thunb. (Cypripedoideae Orchidaceae) a lady’s slipper orchid endemic to East Asia

摘要

Development of anther and pollen grain in Cypripedium japonicum. a. Cross section (CS) of young pollinia. b. CS of young pollinia showing wall layers. c. Cytokinesis in microspores. d. CS of pollinia showing anther wall and microspore tetrads. e. CS of mature pollinia with variously shaped pollen tetrad/polyads. f, g. CS of mature pollinia showing development of wall thickenings in endothecium and dehiscence of anther. h. Mature anther wall with papillate epidermis and fibrous thickenings in endothecium. i. Two nucleate mature pollen grains. Abbreviations: ent, endothecium; ep, epidermis; gc, generative cell; ml, middle layer; mmc, microspore mother cell; po, pollinia; pt., pollen tube; t, tapetum; v, nucleus of the vegetative cell. Scale bars: a = 500 μm, b, d = 50 μm, c-i = 30 μm, e, f, g, h= 100 μm