秋海棠属侧膜组的分类学研究
魏志丹
学位类型博士
导师李德铢
2010-05
学位授予单位中国科学院研究生院
学位专业植物学
摘要秋海棠属侧膜组(Begonia sect. Coelocentrum Irmsch.)近50种,仅分布于中国广西、云南东南部、贵州南部及越南北部的石灰岩地区,是一类较为严格的喜钙植物。本文通过子房胎座形态、胚胎学、叶表皮微形态、文献资料收集、标本查阅以野外考察等方面对秋海棠属侧膜组进行了分类学研究。主要研究结果如下:1. 通过石蜡切片对秋海棠属侧膜组及近缘组26种植物的胎座形态进行了研究,结果发现:1)子房胎座形态特征在秋海棠属组内较稳定,可以作为划分组的主要依据;2)在侧膜组内,不同种胎座的发育程度及愈合程度有所差别;3)秋海棠属侧膜组的胎座发育过程见证了个体发育再现系统发育的规律,从各个组的胎座类型推测,秋海棠属植物各类群的演化趋势可能为:由侧膜胎座类向中轴胎座类演化,由2(或多)裂片类向单裂片演化,侧膜组为基部类群。2. 首次观察了刘演秋海棠B. liuyanii C.-I Peng, S. M. Ku & W. C. Leong的胚胎发育过程,其胚珠多数,成熟胚珠倒生,双珠被,厚珠心,大孢子四分体直线形排列(少数T形和倒T形),合点端的大孢子发育,蓼形胚囊;花药具4个小孢子囊,成熟的花药壁为基本型,由表皮、药室内壁、中层和绒毡层组成,绒毡层为分泌型,成熟的花粉粒具3孔沟。另外,发现其胚珠有一特有结构,外珠被最外层细胞体积较大且明显径向伸长,内含物较少,个别细胞内充满单宁物质,目前这一特有的结构特征在其它科植物中尚未见报道。3. 通过扫描电镜观察,对秋海棠属侧膜组及其近缘组共42种3变种的叶表皮微形态特征进行了描述和总结,结果表明:叶表皮微形态特征在组等级上的一致性较差,但对组内种的划分具有一定的参考价值,通过叶表皮微形态观察比较,对一些种类做出异名或降为变种处理。在侧膜组内,一些种类的表皮微形态特征表现出较高的一致性,它们可能是一个较自然的分类群,可以作为组下等级划分的依据。4. 通过野外考察、文献资料收集、馆藏标本的查阅,并结合胎座形态和叶表皮形态的研究,对秋海棠属侧膜组进行了分类修订,确定该组植物共有46种4变种,对所有种类进行了描述,并列出了分种检索表,澄清了一些种类的分类学问题:1)根据胎座特征、生境及生长习性等,建议将昌感秋海棠B. cavaleriei H. Lév.,靖西秋海棠B. jingxiensis D. Fang & Y. G. Wei和少瓣秋海棠B. wangii T. T. Yü从秋海棠组B. sect. Diploclinium(Lindl.) A. DC.放到侧膜组;2)根据叶表皮微形态特征,将巴马秋海棠B. bamaensis Yan Liu & C.-I Peng处理为越南秋海棠B. bonii Gagnep.的异名;取消德保秋海棠B. debaoensis C.-I Peng, Yan Liu & S. M. Ku作为独立种的存在,将其处理为变种疏毛越南秋海棠B. bonii var. remotisetulosa Y. M. Shui & W. H. Chen的异名,同样将蛛网脉秋海棠B. arachnoidea C.-I Peng, Yan Liu & S. M. Ku从种降为变种,作为硬毛伞叶秋海棠B. umbraculifolia Y. Wan & B. N. Chang var. flocculosa Y. M. Shui & W. H. Chen的异名处理。
资助项目Begonia sect. Coelocentrum Irmsch. is a strict calciphilous plant. It consists of about 50 species, and is exclusively distributed in limestone areas of Guangxi, SE Yunnan, S Guizhou of China, and N Vietnam. Based on morphology of ovary placentae, embryology, micromorphology of leaf epidermis, literature collections, specimens examinations and field works, the taxonomy on Begonia. sect. Coelocentrum is studied. The main results are summarized as follows: 1. The Morphology of placentae of 26 species is observed through paraffin sections, results are summarized as follows: 1) Morphological characteristics of placentae are stable in sections of Begonia,can be taken as a primary evidence between sections; 2) In Begonia. sect. Coelocentrum, different species placentae have different development and considerably varied degrees of concrescence; 3) The types of placentae in other sections of Begonia could all be found in Begonia. sect. Coelocentrum. In this section, the development processes of placentae have implied the phylogeny of other sections. Based on the placentae types of every sections, the evolution trends in Begonia probably can be suggested: from groups with parietal placentae to groups with axial placentae, from 2- (or more) lobates to 1-lobate placentae, and so B. sect. Coelocentrum. is the base group.2. Embryological features of B. liuyanii C.-I Peng, S. M. Ku et W. C. Leong are reported for the first time. Ovules are numerous. The mature ovules are anatropous, bitegminous, and crassinucellate, usually linear tetrad (rarely T-shaped and inverted T-shaped).The embryo sac is formed by the chalazal megaspore in the tetrad. It is the polygonum type. The anther of each stamen is tetrasporangiate; mature anther wall falls into the basic type of development, including 4-layered (a epidermis, a fibrous endothecium, a ephemeral middle layer and a secretory anther tapetum), mature pollen grains with 3-grooves. Additionally, the ovule has a unique structure that the cells of outer layer of integument are significantly larger with radial extension, fewer inclusions, individual cells filled with tannin substances, At present, this unique structure has not yet been reported in other plants. 3. Leaf epidermal micromorphorlogy characters of 42 species and 3 varieties in B. sect. Coelocentrum and related sections, are examined under scanning electron microscope (SEM), results are showed that: Characteristics of leaf epidermal micromorphology have poor consistency in sections, but can provide important evidences for the division of species and varieties in Begonia. sect. Coelocentrum. By compared observations of leaf epidermis, some species are reduced to synonymy or degraded from species to variations. Moreover, the epidermal morphology of some species in Begonia. sect. Coelocentrum showed high consistency, t may be a relatively natural taxonomic character and can be used as the proofs for classification under the sections.4. Based on field works, literatures, specimen examinations, and morphology of placentae, micromorphology of leaf epidermis, Begonia. sect. Coelocentrum is revised. There are 46 species and four varieties are recognized in the world, the morphological characters and distributions are described and a key for the identification is also given, some taxonomic problems are clarified. 1) According to characters of placentae, habitats and habits, B. cavaleriei H. Lév.,B. jingxiensis D. Fang & Y. G. Wei,and B. wangii T. T. Yü are suggested to be transferred from B. sect. Diploclinium into B. sect. Coelocentrum; 2) On the basis of Leaf epidermal micromorphorlogy characters, B. bamaensis Yan Liu & C.-I Peng is treated as a synonymy of B. bonii, B. debaoensis C.-I Peng, Yan Liu & S. M. Ku is degraded from species to a variation and treated as a synonymy of B. bonii Gagnep. var. remotisetulosa Y. M. Shui & W. H. Chen, B. arachnoidea is also degraded to a variation and treated as a synonymy of B. umbraculifolia Y. Wan & B. N. Chang var. flocculosa Y. M. Shui & W. H. Chen
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16052
专题昆明植物所硕博研究生毕业学位论文
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魏志丹. 秋海棠属侧膜组的分类学研究[D]. 中国科学院研究生院,2010.
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