大戟科麻疯树属三种植物花器官发生

利用扫描电子显微镜观察了大戟科Euphorbiaceae麻疯树属Jatropha麻疯树J. curcas L.、佛肚树J. podagrica Hook.和棉叶麻疯树J. gossypifolia L.花器官发生。结果表明: 麻疯树、佛肚树和棉叶麻疯树花萼原基均为2/5型螺旋发生。在同一个种不同的花蕾中, 花萼的发生有两种顺序: 逆时针方向和顺时针方向。远轴面非正中位的1枚先发生。5枚花瓣原基几乎同时发生。雄花中雄蕊两轮, 外轮对瓣, 内轮对萼。研究的3种麻疯树属植物雄蕊发生方式有两种类型: 麻疯树亚属麻疯树的5枚外轮雄蕊先同时发生, 5枚内轮雄蕊后同时发生, 佛肚树亚属佛肚树和棉叶麻疯树雄蕊8-9枚, 排成两轮, 内外轮雄蕊同时发生。雌花的3枚心皮原基为同时发生。麻疯树属单性花, 雌花的子房膨大而雄蕊退化, 雄花的雄蕊正常发育, 子房缺失。根据雄蕊发生方式, 支持将麻疯树属分为麻疯树亚属subgen. Jatropha和佛肚树亚属subgen. Curcas。

Floral organogenesis of three species of Jatropha (Euphorbiaceae)

Floral organogenesis of three species of the genus Jatropha L. of the family Euphorbiaceae, viz., J. curcas L., J. podagrica Hook. and J. gossypifolia L., was studied with scanning electron microscope (SEM). The first sepal primordium is initiated in non-median abaxial position and the second one in median adaxial position. Five sepal primordia arise in a 2/5 sequence on the periphery of the floral apex and are initiated anticlockwise or clockwise in different floral buds of the same species. Five petal primordia initiate simultaneously. There are dicyclic stamens in male flowers with the outer whorl of stamens opposite to the petals (obdiplostemony) and inner whorl opposite to the sepals. Two types of stamen development exist in the genus. In J. curcas, belonging to subgen. Curcas, five stamen primordia of the outer whorl arise simultaneously at first and then five of the inner whorl initiate simultaneously. In J. podagrica and J. gossypifolia, belonging to subgen. Jatropha, eight to nine stamen primordia of the two whorls arise simultaneously. In the female flowers, three carpel primordia appear simultaneously. The flowers of these three species are unisexual. In the female flowers, the ovary bulges and the stamens degenerate, whereas in the male flowers, the stamens grow normally but the ovary is absent. The division of the genus with subgenera is supported by the stamen development.