【作者】 孙会忠；

【导师】 贺学礼；

【作者基本信息】 西北农林科技大学 ， 植物学， 2007， 博士

【摘要】 绢蒿属(Seriphidium)隶属于菊科(Compositae)春黄菊族(Tribe Anthemideae),全世界约有130余种,主要分布于北温带的亚欧大陆、北美和北非。中国植物志第76卷第1分册记载,我国有31种3变种,归为三组,即Sect. Juncea,Sect. Seriphidium,Sect. Minchünensa,主要分布于中亚及我国西北干旱地区、北美洲西部、中东、非洲北部。绢蒿属植物不仅有较高的药用、饲用和生态价值,而且部分种类是西北干旱草原的建群种和优势种,具有很大的开发潜力。自从Poljakov于1961年从Artemisia划分出来之后,仅有林有润对其进行过一些系统学方面的研究。目前,对该属的系统划分,异议颇多,故我们从解剖学、果实纹饰、孢粉学、核型等角度出发,对其做了较为系统的研究和探讨,分述如下:1.对绢蒿属及其10属外类群植物的主要植物分类学性状进行了比较。结果显示,绢蒿属植物的主要分类学性与蒿属最为接近,说明二者具有较近的亲缘关系,但二者的两性花截然不同,说明二者已经演化成区别明显的两个类群;与其它9属外类群植物相比的区别明显,故将绢蒿属作为一个属的分类学处理是恰当的。基于叶表皮、气孔等特征,对绢蒿属的演化进行了探讨,并认为将东北蛔蒿(S. finitum)从绢蒿系中划出,另立东北蛔蒿系是恰当的。2.运用光镜和电子扫描显微镜对绢蒿属及其若干外类群的果实微形态特征进行了研究,结果显示,绢蒿属及其外类群植物的种子微形态特征表现出丰富的多样性,果实微形态特征,特别是果实的纹饰类型,具有明显的属级水平上差异;研究结果为目前存在较大争议的几个单种属或寡种属提供了果实微形态特征方面的新证据,填补了该方面的研究空白,支持它们(如紊蒿属、栉叶蒿属、茼蒿属)作为属的分类学处理;绢蒿属与其外类群在果实微形态特征(特别是果实纹饰)区别明显,作者认为绢蒿属作为属的分类分类学处理是合理的。绢蒿属果实的微形态特征与蒿属相比最为接近,说明二者亲缘关系较其它外类群属近。3.运用光镜和电子扫描显微镜对绢蒿属植物花粉形态特征进行了系统性的研究,其中扫描电镜资料为首次报道。结果表明:种绢蒿属植物花粉的立体形状为长球形、球形或近球形,赤道面观为圆形或椭圆形,极面观为三裂片圆形;花粉粒较小,极轴(P)长22.52(16.23 ~ 27.18)μm,赤道轴(E)长17.22(15.51 ~ 23.13)μm,P/E平均值为1.31;具三孔沟,孔沟长达极区,不弯曲,沟的末端在极面上不连接形成合沟(存疑种除外);外壁2层,外层厚于或近等厚内层;花粉外壁纹饰在光学显微镜下粗糙状,在扫描电子显微镜下以刺状-颗粒状复合纹饰为主。对花粉形态特征的分类学意义进行了探讨。4.对13种中国绢蒿属植物进行了核型研究,结果显示,13种植物种的染色体均具有9基数的二倍体核型特征,除草原绢蒿(S. schrenkianum)和伊犁绢蒿(S. transiliense)为2n=36外,其余11种均为2n=18。从核型上可将13种绢蒿属植物分为2A和2B两种类型。其中只有草原绢蒿和伊犁绢蒿为2B,其余为2A。染色体随体的数量和位置在种间存在一定差异。按照Stebbins核型对称性原则,13种绢蒿属植物由对称向不对称方向演化的大体方向是:三裂叶绢蒿→伊犁绢蒿→伊塞克绢蒿→草原绢蒿→新疆绢蒿→沙湾绢蒿→蛔蒿→民勤绢蒿→针裂叶绢蒿→沙漠绢蒿→纤细绢蒿→小针裂叶绢蒿→白茎绢蒿。结果支持三裂叶绢蒿为最原始种的分类学处理,伊犁绢蒿在绢蒿系的系统位置应调置草原绢蒿之前,其它种的系统位置保持不变。13种植物的核型研究均为首次报道,填补了关于中国绢蒿属植物研究的一项空白。5.通过广泛的查对标本、长时间的野外实地考察以及室内解剖实验,测量和记录了植物种的基本信息。确定我国现分布有31种,5变种,其中不含存疑种。6.对中国绢蒿属现实生物地理分布、历史地理及植物区系地理以及分布式样等方面进行了描述和探讨,得出以下结论:绢蒿属在我国分布具有很强的地域性,新疆北疆分布最多,为现代分布中心之一;根据古植物化石与孢粉研究资料证明,绢蒿属的起源中心与蒿属相同,可能在在乌拉尔山附近亚北极地区或稍靠南区域的中生或稍干旱森林或荒漠草原环境。绢蒿属自从祖先种中分化出来之后,自起源中心向东、西、南三个方向迁移,迁移和进化的主要动力为地质变迁和第三、第四纪冰期的胁迫;绢蒿属在我国分布式样基本呈“三带”分布,即阿尔泰山一线的阿勒泰-克拉玛依一带、天山一线的伊宁-乌鲁木齐-哈密一带、昆仑山一线的喀什-阿克苏-和田一带;种间替代比较明显;演化路径纵向由北向南,横向由西向东推进;世界绢蒿属植物区系地理分为3个大区,我国绢蒿属占2大区,4亚区。更多还原

【Abstract】 The genus Seriphidium, belonging to the tribe Anthemidae of Composite, there are more than 130 species distributed in Asia-Europe continent, North America and North Africa of temperate to boreal regions of the North Hemisphere. About 31 species, 3 varieties according to the record of Flora Reipublicae Popularis Sinicae in vol 76, No.1 which were classified into 3 Sect, namely, Sect. Juncea, Sect. Seriphidium, Sect. Minchünensa. They distributed mainly northwest arid of China, west areas of North America, the Middle East and North Africa. Seriphidium have important value in medicinal, fodder and ecology, moreover, some possess important affect on population regulation in northwest arid prairie, having immense potentialities in developing.From Seriphidium divided from Artemisia by Polkakov in 1961, only Lin yourun contributed to it in taxonomy. Even so, there still various problems needed to further research. We have put emphasis mainly on anatomy, micro-characteristic of fruit, sporopollen, etc. to study, and the major achievement obtained as follow:1. Comparative on main characteristics of systematic botany between Seriphidium and its 10 genus allies.The results show that Seriphidium and Artemisia have the near genetic relationship comparatively, but their monoclinic are entirely different, which illustrate clearly that Seriphidium and Artemisia is two different plant categories; possess the different characteristics obviously between Seriphidium and its 9 genus allies. As a separate unit of genus for Seriphidium are reasonable. Base on the results above, we also discussed the evolution of Seriphidium, and we put forward a proposal to establish the Ser. finitum.2. The micro-characteristics of fruit were studied under LM and SEM. The results that the micro-characteristics of fruit from Seriphidium and its allies show rich variety, especially on the ornamentation of fruits between genuses; the consequence have produce new proof for controversy genus, such as Elachanthemum, Neopallasia, Chrysanthemum, to as a independently unit of genus; there have distinct distinguish between Seriphidium and its allies in micro-characteristics of fruit, consequently we hold Seriphidium as a genus is reasonable. Resembled in micro-characteristics of fruit between Seriphidium and Artemisia reflect their genetic relationship.3. Pollen morphology of taxa of the genus Seriphidium, distributed in China, was studied with LM and SEM. The results show that the shape of pollen grains are prolate, spheroidal or subspheroidal in equatorial view, and three-lobed in polar view; the size of pollen grains was 22.52(16.23 ~ 27.18)μm in the polar axis and 17.22(15.51 ~ 23.13)μm in the longest equatorial, the average of P/E is 1.31; the apertures are three-colporate, which extended to polar area and no converged (except the un-identified species); exine is composed with two layers under LM and the outer lawyer often thicker than the inner; the ornamentation of the exine is coarse under LM and is spinule-granular. The systematic significance of pollen morphology is discussed in the end.4. The karyotype analysis of 13 species from Seriphidium, distributed in China, were studied, and the results show all 13 species have diploid characteristic of karyotype and the cardinal number is 9, exception S. schrenkianum and S. transiliense (2n=36), other 11 specie were 2n=18. The type of karyotype can be divided 2A and2B (only S. schrenkianum and S. transiliense). The number and position of SAT are different between species to some extent. According to the principle of symmetrical characteristic by Stebbins, the orientation of evolution of 13 species, from symmetry to dissymmetric, is : S. junceum, S. transiliense, S. issykkulense, S. schrenkianum, S. kaschgaricum, S. sawanense, S. cinum, Seriphidiun minchünense, S. sublessingianum, S. santolinum, S. gracilescens, S. amoenum, S. terrae-albe. Stand by regarding S. junceum as the most original species in Seriphidium; proposal reverses the position of S. transiliense and S. schrenkianum. The karyotype analysis of 13 species is report first time.5. By check a large number of specimen, field work and indoor experiment, we have record much information. Base on it, we fix 31 species, 5 varieties distributed in China.6. Discussed the distribution present in China, Flora, the pattern of distribution, etc. Conclusion: the distribution of Seriphidium in China has obvious feature of region, Xinjiang province is the center of contemporary distribution; the available fossil record and sporopollen prove that Seriphidium and Artemisia have the identical origin place which may be located desert steppe or arid forestry of Wulaer Mt. in sub arctic; from divided from its ancestor, Seriphidium plants have three migration from the origin center, namely, east, west and south, the motive power of migration is the gradual changes of geology and stress of glacial epoch; the pattern of distribution in China present“three-band”, that is Aletai-Kelamayi nearby Aertai Mt.; Yining-wulumuqi-Hami nearby Tian Mt.; Keshi-Akesu-Hetian nearby Kunlun Mt.. The substitution between species in different region is obvious; the route of migration is from north to south in vertical, and from west to east in lateral. The flora of Seriphidium in China can be divided two districts, including five sub districts.更多还原