垂头菊属（菊科-千里光族）的分类学研究

Cremanthodium (Asteraceae-Senecioneae) is a typical high-alpine genus distributed in the Sino-Himalayan region, with 70 species being recognized. Owing to the lack of critical survey of literature and type material, poor knowledge of both macro- and micro-morphological characters as well as insufficient analysis of character variations in previous works, many fundmental taxonomic problems, such as misinterpretation of the identity of species, description of old species as new and inaccuracy of geographical information of taxa, remain unsolved in the genus. The generic delimitation between Cremanthodium and its closest ally, Ligularia, is not decisively settled, and the current classification system of Cremanthodium, proposed on the basis of few gross-morphological characters, is also poorly predictive. Previous molecular analyses sampled only a small portion of Cremanthodium species and utilized few phylogenetically low-informative DNA fragments. This project aims to tackle these problems through multidisciplinary approaches. We will conduct a critical survey of all the relevant literature and herbarium specimens, extensive field observations, and a comprehensive investigation of all the macro- and micro-morphological characters, and then carefully re-evaluate the variation patterns of all these characters and determine their taxonomic applicability at different levels. We will strictly base our taxonomic decisions on the results of re-evaluation of the characters. In the light of our thorough revision of the genus at species level, we will attempt to re-construct its phylogeny using evidence from different disciplines, and apply the results to improve the classification system, clarify the evolutionary patterns of some important characters, and, if necessary, re-delimit the generic circumscription. Our final objective is to produce a taxonomic monograph of Cremanthodium in the true sense, which should synthesize all the known information about the genus. This project will help us gain a better understanding of the species composition and differentiation in China, and will also provide basic scientific information for the conservation and sustainable utilization of plant resources in Cremanthodium, for all the known species occur in China and, having very elegant flowers with musk-like fragrance, would prove of great garden value if they could be cultivated in this country.

垂头菊属（菊科-千里光族）是中国-喜马拉雅地区的特有属，目前共记载有70种。由于前人在文献考订、标本检查和野外考察以及实验室等方面的工作有欠深入，对很多性状（包括宏观和微观性状）的变异式样缺乏深入理解，分子系统学研究涉及的种类和所用DNA片段偏少，因此该属颇多基本分类学问题尚待解决。本项目拟紧密结合文献考证、标本和野外活植物观察以及实验室研究手段，对垂头菊属具有潜在分类学价值的性状进行全面研究，评价和确定各性状的分类和系统学价值，全面完成种级水平的分类修订，并利用多学科证据重建该属与其近缘属橐吾属的系统发育关系，阐明垂头菊属与橐吾属的属间界限和改进垂头菊属的属下分类系统,使垂头菊属的分类达到专著水平。垂头菊属目前承认的所有种类在我国均有分布，花美观，有麝香气，是重要的高山花卉植物资源。澄清其分类学问题可增加对我国物种组成和分化等问题的理解，同时为植物资源的利用和保护提供基础科学资料。

利用多学科手段对垂头菊属（Cremanthodium Benth.）（菊科: 千里光族）进行了分类学研究。我们全面收集了垂头菊属及其近缘属的分类学文献，建立了该属完善的文献数据库，研究了国内外主要标本馆的33000余份垂头菊属及其近缘属的标本，采集了68种垂头菊属植物及其近缘属多种植物的标本、 DNA材料和活材料。形态学研究表明，叶脉类型、舌花形状、植株颜色、叶片形状、颜色及毛被、苞片数量及形状等是垂头菊属种级水平比较可靠的分类性状。对垂头菊属50种、104居群及其最近缘的属即橐吾属（Ligularia Cass.）进行了染色体研究，确认了垂头菊属及橐吾属的染色体基数为x = 29、 30，其中x = 29为比较常见的一个基数。分子系统学研究表明目前定义的垂头菊属和橐吾属均非单系类群，即使将二者合并也不能构成单系，但合并后的系统树分为5个与地理分布较为相关的大支。