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1.
1. Uplifting of Qinghai-Xizang plateau has brought great influence on the origination and distribution of species inside the genus Salix. There are 91 sp. (incl. 2 cult. sp.), 16 var. and 3 f. belonging to 15 Sect. in this region, among these species the endemics attain to 58 sp., 14 var. and 3 f. So it has become one of the most important centres of distribution of Salix in the world. Species common with other regions attain only to 32. Thus it is also clear that correlation between salicaceous flora in this region and that of other regions is not so much developed, and that the salicaceous flora of Qinghai-Xizang plateau was mainly originated autochthonously during the upheaval of plateau. 2. Along a demarcation line delineated from Gyirong through Lhasa and Qamdo to Lanzhou, to the north-western region the total number of species of this genus is summed up to 7 sp. and 1 var. (incl. 2 cult. sp.), and they distribute only in the West Himalaya and Pamir-Kunlun regions. Besides 2 cult. sp., there is only 1 endemic, and others all should be migrants from Europe or West Asia. In the south-eastern part, because the climate is moister, the species of Salix may be summed up to 84 sp., 15 var. and 3 f., among them 73 sp., 20 var. and 3 f. are endemics, accounting for 68 percent of the total. 3. In East Himalaya and South Henduan Shan (southward of lat. 30°N.) there are 78 sp., 12 var. and 4 f., among them 50 sp., 10 var. and 2 f. are endemics. They represent the different stages of phylogenetic development of this genus. So here may be the centre of origination and distribution of Salix species in the all Sino-Himalaya flora. The common species between East Himalaya and South Henduan Shan regions attain to 41. Because the latter forms a part of Sichuan and Yunnan plateau and the former did not become a land until Quaternary Period, the plants of the former mainly are the migrants from the latter. 4. The most characteristic group of Salix in this region is Sect. Lindleyanae Schneid. with a total of 18 sp. and 1 var. This group adapting to the somewhat environment changes is quite different from Sect. Retusae A. Kern. in the Arctic and high mountains of higher latitudes in many characters, so it should be originated autochtonously, and it is certainly not a migrant from Arctic. This Sect. seems to be developed from Sect. Floccosae Hao and in turn from Sect. Sclerophyllae Schneid. and Sect. Denticulatae Schneid. This developmental direction has assumed an important branch in the phylogenetic development of the whole genus. 5. In addition, there are two interesting and important regions on the north-eastern and eastern to Qinghai-Xizang Plateau, i. e. on the north-east Anymaqen Shan (Amnemachin mountain) and on the east Qiong Lai Shan. There are many endemic species pertaining to these two parts, among these species some may be ancient relicts since Tertiary. It is to be expected that more additional scientific results will be obtainedafter some more extensive works done in these two regions.  相似文献   

2.
1. The distribution of Salix species among the continents. There are about 526 species of Salix in the world, most of which are distributed in the Northern Hemisphere with only a few species in the Southern Hemisphere. In Asia, there are about 375 species, making up 71.29 percent of the total in the world, including 328 endemics; in Europe, about 114 species, 21.67 percent with 73 endemics; in North America, about 91 species, 17.3 percent with 71 endemics; in Africa, about 8 species, 1.5 percent, with 6 endemics. Only one species occurs in South America. Asia, Europe and North America have 8 species in common (excluding 4 cultivated species). There are 34 common species between Asia and Europe, 14 both between Europe and North America and between Asia and North America, 2 between Asia and Africa. Acording to the Continental Drift Theory, the natural circumstances which promoted speciation and protected newly originated and old species were created by the orogenic movement of the Himalayas in the middle and late Tertiary. Besides, the air temperature was a little higher in Asia than in Europe and North America (except its west part) and the dominant glaciers were mountainous in Asia during the glacial epoch in the Quaternary Period. Then willows of Europe moved southwards to Asia. During the interglacial period they moved in opposite direction. Such a to-and-fro willow migration between Asia and Europe and between and North America occurred so often that it resulted in the diversity of willow species in Asia. Those species of willows common among the continents belong to the Arctic flora. 2. The multistaminal willows are of the primitive group in Salix. Asia has 28 species of multistaminal willows, but Europe has only one which is also found in Asia. These 28 species are divided into two groups, “northern type” and “southern type”, according to morphology of the ovary. The boundary between the two forms in distribution is at 40°N. The multistaminal willows from south Asia, Africa and South America are very similar to each other and may have mutually communicated between these continents in the Middle or Late Cretaceous Period. The southern type willows in south Asia are similar to the North American multistaminal willows but a few species. The Asian southern type willows spreaded all over the continents of Europe, Asia and North America through the communication between them before the Quaternany Period. Nevertheless, it is possible that the willows growing in North America immigranted through the middle America from South America. The Asian northern type multistaminal willows may have originated during the ice period. The multistaminal willows are more closed to populars in features of sexual organs. They are more primitive than the willows with 1-3 stamens and the most primitive ones in the genus. 3. The center of origin and development of willows Based on the above discussion it is reasonable to say that the region between 20°-40°N in East Asia is the center of the origin and differentiation of multistaminal willows. It covers Southern and Southwestern China and northern Indo-China Pennisula.  相似文献   

3.
青海柳属植物地理分布及其区系特点   总被引:1,自引:0,他引:1  
通过野外调查和查阅大量标本及文献资料,对青海省柳属(SalixL.)植物地理分布和区系特征进行了研究。青海产柳属植物多达45种(含种以下5变种、1变型),隶属15个组(Sect.),分别占青藏高原组、种的100%、40.9%和我国组、种的40.5%、17.5%,居我国第4位。青海柳属植物主要分布于青海东部,包括祁连山系东段和青南高原东南部,垂直分布集中于海拔2000~4000m,是世界柳属植物海拔分布最高的地区之一。青海柳属植物区系特征表现在:(1)种类丰富;(2)多型性突出;(3)地理成分较复杂,以欧亚大陆温带分布成分和青藏高原分布成分为主,中国特有分布占有一定的地位;(4)特有现象不明显,仅占青海种数的8.9%;(5)两雄蕊或单雄蕊的进化类群占绝对优势,占青海种数的93.3%。青海柳属植物与邻近的东部(甘肃东部、陕西)和东南部(四川西部、西藏东部)地区联系密切。由于第三纪以来喜马拉雅和青藏高原不断抬升,形成了适应高寒和干旱环境的青海柳属植物的分布与区系特征。  相似文献   

4.
The genus Calligonum L. includes a total number of 35 species in the world, of which 24 are in China. They are grouped into four sections, of which Sect. Calliphysae (Fisch. et Mey.) Borszcz. is the most primitive and Sect. Medusae Sosk. et Alexender. is the most progressive. The Calligonum L. is an ancient genus in the arid desert flora, and central Asia is the place of its origin. Some species migrated to the Middle Asia and Iran, developing into a second center there. Also, some newly occurred species of the Middle Asia emigrated eastwards to central Asia, so the genus Calligonum L. in China comprises components of both central Asia and the Middle Asia. The genus Calligonum L. is distributed in North Africa, south Europa and Asia, and China is the eastmost part of the distribution range. They grow in Nei Monggol, Gansu, Qinghai and Xinjiang. There are 12 species in the Zhuengar Basin, covering 50 percent of the total number of species in China, amd thus the genus is the most abundant there.  相似文献   

5.
中国针茅属植物的地理分布   总被引:12,自引:0,他引:12  
本文论述了中国针茅属植物的地理分布、生态特点及其与植被分布的关系。中国针茅属有32种1亚种及4变种,据该属各个种所处环境中的气候和土壤等因素的变化,不同种的分布也各异。属的分布区的类型属于吴征镒(1979)的中国植物区系分区的泛北极植物区中的6个植物亚区,即亚洲荒漠植物亚区,欧、亚森林植物亚区,青藏高原植物亚区,中国-喜马拉雅植物亚区,欧、亚草原植物亚区及中国-日本森林植物亚区。  相似文献   

6.
对湖北鳞毛蕨后植物的地理分布和区系特点进行了研究。鳞毛蕨后植物广布于世界各地,该后的分布和多样性中心位于中国西南部和东喜马拉雅山区;另一中心则位于日本,中国东南部和南部。鳞毛蕨后是一个自然的北温带分布属。中国有鳞毛蕨后植物134种(包括7变种),西南地区(云南、四川、贵州等)是国产鳞毛蕨属植物分布最集中的地区。区系分析表明:湖北鳞毛蕨后植物种类比较丰富,有36种,主要分布于鄂西北和鄂西南山区,是构成湖北森林植物区系林下草本植物的主要成分之一;地理成分比较复杂,种的分析显示出以中国一日本分布和中国持有分布为主的特点;与相邻省鳞毛蕨属植物区系的关系比较密切;区系过渡性明显。  相似文献   

7.
A Study on Aroids in Gaoligong Mountains   总被引:1,自引:1,他引:0  
高黎贡山是云南与缅甸北部交界的山脉。这一地区的植物区系深受科学界的注意。由于地形险峻,自然植被保存完好,但研究的也较少。高黎贡山是特有现象最丰富的地区。这里有天南星科植物58 种,属于11个属,以南星属为主,含35种。天南星科植物中,10种为高黎贡山所特有,6种为分布到高黎贡山的云南特有种,7种为分布到高黎贡山的中国特有种。植物地理学研究表明高黎贡山的植物区系是东亚植物区系的一部分,是东喜马拉雅植物区系的起源地之一。  相似文献   

8.
The geographical distribution of Liliaceae (s. str. ) is analysed on the basis of the floristic regions proposed by Takhtajan. Some conclusions may be proposed as follows: 1.Liliaceae (s. str. ) consists of nine genera and about 513 species, distributed primarily in the north temperate zone. Statistics shows clearly that the Irano-Turanian Region is most abundant in number of species, The Eastern Asian Region with total nine genera of the family is the diversity centre of Liliaceae (s. str. ). 2. The distribution patterns of the genera may be divided into: 1 ) North temperate distribution pattern: Lloydia, Erythronium, Fritillaria and Lilium; 2) Old world temperate distribution pattern: Gagea and Tulipa; 3) West Asia to Himalayas and Southwest China distribution pattern: Notholirion; 4) East Asia distribution pattern: Cardiocrinum and Nomocharis. 3. The Sino-Himalayas is one of the key regions in studying the evolution of Liliaceae (s. str. ) All nine genera occur in the Eastern Asian Region with most species distributed in Southwest and Northwest China. Chorologically, five genera (Fritillaria, Lilium, Cardiocrinum, Nomocharis and Notholirion) of the Lilieae are overlapped each other in the Sino-Himalayas, showing its diversity centre in this region. The Lilieae is a main stock in the Liliaceae (s. str. ), The genus Nomocharis in this tribe may have been newly differentiated from Lilium in the course of the uplift of Qinghai-Xizang Plateau, a view also supported by Xie Xiao-yang et al.. The place of its origin was considered to be in the southern part of the Hengduan Mountains. 4. The distributions of some species in Liliaceae (s. str. ) seem to be significant for dividing some floristic regions: 1 ) Some species of Fritillaria (F. unibracteata Hsiao et K. C. Hsia, F. przewalski Maxim. ex Batal. , F. crassicaulis S. C. Chen, F. cirrhosa D. Don. , F. delavayi Franch. , F. dajinensis S. C. Chen, F. davidii Franch. , F. sinica S. C. Chen and F. sichuanica S. C.Chen) are only distributed in Sino-Himalayan forest subkingdom, while others (F. taiparensis P. Y. Li, F. yuzhongensis S. C. Chen, F. monantha Migo, F. anhuiensis S. C. Chen et S. F. Yin, F. thunbergii Miq. , F. maximowizii Freyn and F. ussuriensis Maxim. ) are restricted to Sino-Japan forest subkingdom. They show a clearly demarcation line between the two subkingdoms, which is identical with what proposed by Wu Cheng-yih. 2) The Eastern Asian Region can be divided into two subkingdoms on the basis of the distribution pattern of the genus Cardiocrinum; C. giganteum (Wall.) Makino and C. gigateum var. yunnanense Leichtlin ex Elwes are restricted to Sino-Himalayan forest subkingdom. C. cathayanum (Wilson) Stearn and C. cordatum (Thunb.) Makino are only found in Sino-Japan forest subkingdom. 3) The distributions of Gagea pauciflora Turcz. , G. triflora(Ledeb.) Roem. et Schult. G. hiensis Pasch, Lloydia tibetica Baker ex Oliver, L. oxycarpa Franch. and L. flavonutans Hara are indicative of a demarcation line between Irano-Turanica Region and Eastern Asian Region. 5. The genus Notholirion occurs in the Eastern Asian Region and Irano-Turanian Region, showing the relationships between the two regions and also between the Chinese flora and Ancient Mediterraneam flora.  相似文献   

9.
百合科(狭义)植物的分布区对中国植物区系研究的意义   总被引:28,自引:1,他引:27  
本文对百合科(狭义)各属的地理分布作了分析,该科植物集中分布于泛北极域,属于北温带的科。该科所有的9个属,只在东亚区全部有分布,而且该区具有百合科(狭义)植物各系统演化阶段的类群,因此,东亚区是该科的多样化中心。其中百合族所包括的5个属(贝母属、百合属、大百合属、豹子花属和假百合属)集中分布于中国西南至喜马拉雅地区,其分布区均在中国-喜马拉雅地区重叠,表明中国-喜马拉雅地区是百合族的多样化中心。百合族是百合科(狭义)的核心部分。因而认为中国-喜马拉雅地区是研究百合科(狭义)植物演化的关键地区之一。从种类的统计分析表明,伊朗-土兰区分布的种类最多,说明伊朗-土兰区是该科的多度中心.文中还从一些属(贝母属、大百合属、顶冰花属和洼瓣花属)内种的分布,提出可作为划分某些植物区的依据。而且,还从假百合属的分布,阐明中国植物区系与古地中海植物区系的亲缘。  相似文献   

10.
The genus Swertia is one of the large genera in Gentianaceae, including 154 species, 16 series and 11 sections. It is disjunctly distributed in Europe, Asia, Africa and N. America, but entirely absent from Oceania and S. America. According to Takhtajan’s (1978) regionalization of the world flora, Swertia is found in 14 regions. Eastern Asiatic region with 86 species, of which 58 are local endemics, 13 series and 9 sections, ranks the first among all the regions. The highest concentration of the taxa and endemics in Eastern Asiatic region occurs in SW China-Himalayan area (Sikang-Yunnan P. , W. Sichuan, W. Yunnan-Guichou Plateau of China and NE. Burma, N. Burmense P. , E. Himalayan P. and Khasi-Manipur P. ). In this area there are 74 species (48 endemics), 12 series, and 9 sections; thus about half species of the world total, three quarters of series and 82% of sections occur in this small area. Besides, the taxa at different evolutionary stages in Swertia also survive here. It is an indication that SW. China-Himalayan area is a major distribution centre of the genus Swertia. In addition, Sudan-Zambezian Region in Africa, with 22 species, 4 series and 2 sections, is a second distribution centre. The primitive type of the genus Swertia is Sect. Rugosa which consists of 2 series and 23 species. It is highly centred in the mountains of SW. China (Yunnan, Sichuan, Guizhou and SE. Xizang) where 2 series and 16 species occur. Among them 15 species of Ser. Rugosae were considered as the most primitive groups in this genus. From our study, the outgroup of Swertia is the genus Latouchea Frahch. , which is distributed in Yunnan, Sichuan, Guizhou, Hunan, Guangdong, Guangxi and Fujian. The two groups overlap in distribution in SW. China. According to the principle of common origin, the ancestor of two genera ap peared most probably in this overlapping area. It was inferred that SW. China Was the birth-place of the genus Swertia. Four sections of Swertia have different disjunct distribution patterns: Sect. Ophelia is of Tropic Asia, Africa and Madagascar disjunct distribution; sect. Swertia is of north temperate distribution; sect. Spinosisemina is in Tropical Asia (Trop. India to S. China and Philipines); sect. Platynema also is in Tropical Asia (Java, Sumatra, Himalayas to SW. China). These disjunct patterns indicate that the Swertia floras between the continents or between continent and islands have a connection with each other. From paleogeographical analysis, Swertia plants dispersed to Madagascar before the Late Cretaceous, to SE. Asian Islands in the Pleistocene, to North America in the Miocene. The distribution of Swertia in Madagascar might be later than that in Asia. Therefore the origin time of the genus Swertia was at least not later than the Late Cretaceous, and might be back to the Mid-Cretaceous. The genus Swertia first fully developed and differentiated, forming some taxa at different evolutionary stages (Rugosa, Swertia, Poephila, Ophelia and Platynema etc. ) in the original area, and these taxa quickly dispersed in certain directions during the Late Cretaceous-Middle Tertiary when the global climate was warm and no much change. There seem to be three main dispersal routes from the origin area to different continents; (1) The westward route i. e. from SW. China, along the Himalayas area to Kashmir, Pakistan, Afghanistan and Iran, and then southwestwards into Africa throuth Arabia. Four sections (Poephila, Macranthos, Kingdon-Wardia and Ophelia) took this dispersal route. Most species of sect. Ophelia dispersed along this route, but a few along southern route and north ern route. Sect. Ophelia greatly differentiated in Africa and the African endemic sectionSect. Montana was derived from it. The two sections form there a second distribution center of Swertia. (2) The southward route, i. e. towards S. India through the Himalayas, and towards SE. Asian islands through C. and S. China, Indo-China. Along this dispersal route sect. Platynema, Sect. Spinosisemina and a few species of Sect. Ophelia dispersed; (3) The northward rout, i. e. northwards across N. China, C. Asia to a high latitude of Euasia, and also through E. Asia into N. America. The following groups took this route: sect. Rugosa, sect. Swertia, sect. Frasera, sect. Heteranthos and sect. Ophelia ser. Dichotomae. Therefore, it seems that the genus Swertia originated in SW. China and then dispersed from there to N. and S. Asia, Africa, Europe and North America and formed the moderndistribution pattern of this genus.  相似文献   

11.
以礼草属的地理分布   总被引:9,自引:0,他引:9  
根据植物类群的地理分布与系统发育相统一的原理,本文讨论了以礼草属的分布中心、起源地、 起源时间和现代分布格局的形成。以礼草属全世界约26种、6变种,隶属于3个组,主要分布于中国,哈萨克斯坦、吉尔吉斯斯坦、塔吉克斯坦、阿富汗和伊朗也有分布。其中,中国的青藏高原汇聚了该属的大多数种类,且不同等级和演化水平的类群均集居于此,使其成为该属的现代分布中心;而该属的原始类群、以及与原始类群很近缘的鹅观草属却分布在这一中心之外的天山地区,加之天山地区自新生代的晚第三纪再次抬升以来,具备了以礼草属发生和繁衍的自然条件,因而天山地区很可能就是该属的起源地,起源时间也可能在晚第三纪或第四纪初。以礼草属自天山起源后,扩散的途径大概有3条,其中西南向途径和东南向途径从东、西两侧侵入青藏高原,在青藏高原得到极度发展,并随着高原的继续隆起,进一步衍生出最高级的类群短穗组,从而形成了以礼草属现今的分布格局。  相似文献   

12.
24 species and 4 varietes of genus Stipa L. of China have been studied and described in this paper. It has been noted that these different species have various geographical distributions, depending on the changes of climatic and edaphic factors of their environments. Based on the study of floral morphology together with ecological and distributional factors, the genus have been divided into 5 sections: 1. Sect. Regelia Tzvel. 2. Sect. Leiostipa Dum. 3. Sect. Barbatae Junge 4. Sect. Stipa 5. Sect. Smirnovia Tzvel. It should be pointed out that the section Regelia as well as two members of section Barbatae, S. purpurea and S. roborowskyi, belong to frigori-xerophilous ecotype, distributing over Qinghai-Xizang Plateau above the forest line. The section Leiostipa belongs to euxerophilous and mesoxerophilous ecotype, distributing widely in northwest, southwest, northeast and east and extends to the forest-steppe vegetational Zone of China. The section Smirnovia and other two members of section Barbatae, S. breviflora and S. orientalis, belong to euxerophilous ecotype, with the latitudinal distribution as far as Nei-Mongo and the yellow soil plateau, with the altitudinal distribution as far as the desert steppe of Sinkang and Qinghai-Xizang plateau. The section Stipa belongs to euxerophilous ecotype, only distributes to the mountain steppe of north Xingkang and the last, section Barbatae is an artificial group having plumes overof the awn only, and its four species have already been mentioned above.  相似文献   

13.
青藏高原和喜马拉雅地区锦鸡儿属植物的地理分布   总被引:9,自引:0,他引:9  
锦鸡儿属Caragana是一个典型的温带亚洲分布属。本属在青藏高原和喜马拉雅约有24种1变种,约占整个属的1/3。这些种类几乎全部处于演化高级阶段,且既有叶轴宿存类群,也有假掌状叶类群。反映出种的分化很活跃,在横断山地区形成本属的分布中心、分化中心。本区内绝大多数种类是特有分布。替代现象主要受气候、植被变化作用,沿横断山和喜马拉雅分布的长齿系Ser. Bracteolatae Kom.是一个典型的替代分布类群。锦鸡儿属植物生态适应性很强,可在其生长的灌丛中形成优势种。 寒化和旱化现象十分突出,它们有一系列森林种、草原种和荒漠种及相关的形态变异。用锦鸡儿属植物进行青藏高原和喜马拉雅区域内的分布区关系分析及最小生成树MST和特有性简约性分析(PAE),表明横断山地区特别是其北部是本属植物的一个地理结点。以此沿横断山向北部唐古特和西部藏东南适应性辐射。横断山和西喜马拉雅联系微弱,看不出植物长距离扩散的踪迹,大多是由于生态因子限制而产生的隔离。虽然本区不可能是锦鸡儿属的起源地,然而,通过本区与邻近地区的地理联系,可推测它们在我国适应性辐射方向是从东北向西南。结合豆科蝶形花亚科其它属化石记录及其分布区局限在温带亚洲等现象,认为锦鸡儿植物是一组特化、晚近衍生的类群,起源于北方东西伯利亚晚第三纪中新世后期至上新世。  相似文献   

14.
论世界芨芨草属(禾本科)的地理分布   总被引:12,自引:0,他引:12  
本文详细讨论了世界芨芨草属的地理分布等问题。1.全世界芨芨草属共有23种1变种,分为5个组。本文对它们进行了系统介绍。2.属的地理分布,最北为北纬62°(羽茅、毛颖芨芨草),最南为北纬26°(林阴芨芨草)。就海拔而论,分布最低的海拔记录为120m(雀麦芨芨草),分布最高的海拔记录为4600m(干生芨芨草和藏芨芨草)。3.本文讨论了芨芨草属5个组(芨芨草组,钝基草组,直芒草组,新芨芨草组,拟芨芨草组)的系统位置,和每个组包括的种类及5个组的分布格局。4.根据塔赫他间世界植物区系区划,统计了每个区的种数,明显看出伊朗—土兰区种类(18/24)是第一位,东亚区(14/24)居第二位。中国有17种,横断山脉地区、华北地区和唐古特地区种数最丰富(10种和9种)。5.研究结果表明:(A)从种的分布格局分析可见,横断山脉地区北部、唐古特地区东部和华北地区西部的交汇地是芨芨草属分布中心。(B)根据芨芨草属形态特征演化趋势分析和地史学资料推测横断山脉地区北部是芨芨草属的起源地。(C)有三条路线向外散布:a)从横断山脉地区向西沿喜马拉雅山脉,经克什米尔地区抵达地中海和中欧;b)从横断山脉向西北经祁连山、天山、塔里木盆地西侧山地,抵吉尔吉斯斯坦伊塞克湖; c)由横断山脉向东北经甘肃、宁夏、陕西、山西、河北和东北,抵达西伯利亚,东达堪察加半岛,西至鄂毕河上游,并经白令海峡陆桥分布到美国内华达山脉和落基山山脉。(D)该属植物集中分布于北半球半湿润、半干旱和干旱地区,以及极端干旱的荒漠区山地。植物的形成、发展和生态适应与气候相联系,并经过长期的适应和进化,塑造了一系列中生、旱中生的形态-生态特征和生活型。  相似文献   

15.
黄土高原蕨类植物区系特点的初步研究   总被引:3,自引:3,他引:0  
对黄土高原的蕨类植物区系组成、分类及其特点进行了研究。结果表明,黄土高原有蕨类植物26科、53属、184种及3变种,种类较多的科有蹄盖蕨科(30种)、鳞毛蕨科(26种)、水龙骨科(20种)、铁角蕨科(12种)、卷柏科(12种)、中国蕨科(11种)及裸子蕨科(10种)等。这7科的种类共计121种,占本地区总种数的64.71%。种类较多的属有鳞毛蕨属(13种)、郑柏属(12种)、耳蕨属(11种)、铁角蕨属(11种)、蹄盖蕨属(10种)、瓦韦属(10种)、铁线蕨属(9种)及岩蕨属(9种)等。这8属的种类共计85种,占本地区总种数45.46%,黄土高原蕨类植物区系属的地理成分可划分为15个分布区类型。热带、亚热带分布类型的有18属,占总属数的41.86%,北温带及寒带分布类型的有22属,占总属数(世界分布属除外)的51.16%,其中,亚洲分布类型的最多,计有16属,占总属数的37.20%,表明黄封同原蕨类植物区系是温带类型,区系地理成分以华北区蕨类植物为主,同时也集中了华中、华东、东北、西北以及西南的蕨类植物。而中国特有的分布属只有1属。  相似文献   

16.
The Rosaceae is one of the five largest families of Xizang flora, consisting of 30 genera with 242 species, the total number of species is slightly less than those of Compositae, Graminae, Leguminosae and Ericaceae in Xizang, amounting to 62.5% of the total number of genera and 28% of the total number of species of the rosaceous flora in China. The four subfamilies of Rosaceae including primitive, intermediate and advanced groups have been found in Xizang. These groups consist of 11 types of floristic elements, i.e. 4 genera belong to cosmopolitan, 9 genera belong to North Temperate, 3, E. Asian-N. American, 3 Sino-Himalayan, 3 Sino-Japanesa, 2 Old World Temperate, 1 Temperate Asian, 2 Mediterranean-W. and O. Asian, 1 C. Asian, I Tropical Asian and 1 endemic to China. It is obvious that Rosaceae in Xizang comprises holarctic, Ancient Mediterranean and paleotropical elements, among which the temperate components are the most dominant. The characteristics of the floristic composition of Rosaceae in Xizang may be summarized as follows: (1) Xizang abounds in both genera and species of the family which are diverse in forms, including the primitive, intermediate and advanced groups, (2) The geographical elements are rather complex, mostly belonging to the temperate, among which the Sino- Himalayan components and the elements endemic to China are dominant, (3) The proportion of plants endemic to China and distributed in Xizang is much higher than those endemic to Xizang itself, but there exist newly arisen species and infraspecific forms or varieties which show that the speciation is apparently still active in Xizang. The rosaceous flora of Xizang is a combination of old and new floristic elements, based on the old floristic components, affected by the upheaval of the Himalayas, the differentiation and speciation have been taking place in the long history. The geographical distribution of Rosaceae in Xizang may be divided into 5 regions, i.e. the northeastern, southeastern, southern, northwestern and northern. The rosaceous plants are most abundant in the southeastern area, next in southern area, fewer in the northeastern and very rare in the northwestern and northern regions. The general tendency of the distribution of Rosaceae in Xizang is that the number of species gradually decreases from the southeast to the northwest and the habit gradually changes from trees, shrubs and herbaceous plants in the southeast to cushion-like scrubs and dwarf perennial herbs in the northwest. These facts clearly show that the uplift of the Himalayas has deeply affected the phytogeographical distribution of Xizang Rosaceae. The rosaceous flora of Xizang has close relationships with those of the adjoring regions, i.e. Yunnan and Sichuan. Besides, it is connected with floras of Nepal, Sikkim, Bhutan nothern Buram and nothern India, but silghtly influenced by the Ancient Mediterranean flora.  相似文献   

17.
文本报道了分布在横断山区域的节肢蕨属(Arthromeris)植物,已知12种,1变种;其中新种2个。讨论了该属在本区的地理水平和垂直分布,并初步探讨了在这一地区分布的种类和亚洲分布的种类之间的地理亲缘关系。  相似文献   

18.
青海省东部地区地处青藏高原和黄土高原的交汇地带。该地区受青藏高原和黄土高原的影响,自然植被与青藏高原上的高寒植被和黄土高原上的植被类型均有一定联系,从而形成该区较为复杂的植被类型。据考察,该地区的主要植被类型包括荒漠草原、草原、森林、灌丛、高寒灌丛和高寒草甸,并在该地区形成明显的垂直分布。在海拔较低的河谷低山分布着与黄土高原相连的植被类型;而海拔较高的山地则分布与青藏高原相连的高寒植被,形成有一定过渡性而又独具特色的植被景观。我们认为,该地区是青藏高原和黄土高原的过渡地带。  相似文献   

19.
中国千斤拔属植物的初步研究   总被引:7,自引:0,他引:7  
韦裕宗   《广西植物》1991,11(3):193-207
本文叙述了千斤拔属名的拉丁学名的变换和研究情况,并研究该属植物国产种的分类、地理分布及其特点。进而对该属植物的习性和苞片、花序、花和叶等诸器官演化趋势作初步探讨,并对该属6个类群之间可能的演化关系、属的起源、分布中心和迁移路线等问题提出初设想。  相似文献   

20.
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