Sporogenesis and Gametogenesis of Pyrgophyllum yunnanense (Zingiberaceae)
苞叶姜大小孢子发生和雌雄配子体发育

We report on the microsporogenesis, megasporogenesis and development of female and male gametophytes of Pyrgophyllum yunnanense. Anthers are 2-sporangiate, and the development of anther walls are classified as basic. The tapetum is glandular. The microspore mother cells give rise to isobilateral tetrads by meiosis. Cytokinesis is successive. The mature pollen grains are 2-celled and are shed singly. The ovary is hypostasy and trilocular. The species shows axial placenta with most ovules. The ovule is anatropous, bitegmic and crassinucellate. The chalazal megaspore in a linear or T-shaped tetrad becomes functional. The development of the embryo sac is polygonum. We performed comparative studies with the closely related species Kaempferia rotunda and Caulokaempferia coenobialis. P. yunnanense is closely related to C. coenobialis and is more distant with K. rotunda. P. yunnanense should be treated as an independent genus.