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1.
This paper deals with the taxa of tribe Arundinarieae Steud. subtribe Pleiobalastinae Keng and Keng f. which comprised three genera (Pseudosasa Makino, Pleioblastus Nakai and Brachystachyum Keng) when it was established in 1957. With the analysis of morphological characters and geographical distribution, a number of revisions connected with the taxon are made as follows:      (1)  Genus Brachystachyum Keng is transferred to the tribe Shibataeeae Nakai ac- cording to its false inflorescence.      (2)  Genus Pseudosasa Makino is transferred to subtribe Sasinae Keng f. according to our study on the numerical taxonomic method.      (3)  Some species of Pleioblastus Nakai established by Keng and Keng f. should be revised. Pleioblastus actinotrichus (Merr. and Chun) Keng f. should be Ampelocalamus actinotrichus (Merr. and Chun) S. L. Chen, T. H. Wen and G. Y. Sheng in subtribe Tham- nocalaminae Keng f.; Pleioblastus dolichanthus (Keng) Keng f. is the synonym of Sinobam- busa tootsik (Sieb.) Makino, belonging to tribe Shibataeeae Nakai. The rest species remain in this genus. Since the genus Pleioblastus is related to genus Arundinaria Michaux., subtribe Pleioblastus Keng and Keng f. does not seem to have a reason to be retained as a subtribe in tribe Arundinarieae Steud., according to the newest Code (1978). A part of it should be a synonym of subtribe Arundinariinae and we may cite it as follows: Subtribe Arundinariinae——Subtribe Pleioblastinae Keng and Keng f. pro parte, syn. nov. The other parts of it should be transferred to other subtribes or tribes.       In addition, one new variety in Branchystachyum, two new species, one new variety in Pseudosasa and six new species, three new varieties in Pleioblastus, are described in this paper.  相似文献   

2.
3.
The first classification for the genus Ormosia was proposed by Bentham. It was followed by Taubert (1892) in Engler and Prantl’s Nat. Pflanzenf., who divided the genus into 2 sections.  On the basis of the pod structure and seed characters Prain (1900) arran- ged the genus in 2 sections with 4 subsections.  In the monograph on the genus Merrill and L. Chen ( 1943 ) limited their taxonomic study to Chinese and Indo-Chinese species, and recognized 34 species and 15 series.  Recently Yakovlev (1971-1976) has treated the ge- nus in 6 separate genera.      In the present paper the author recognizes 35 species, of which 7 species and 2 varie- ties are new.  The Chinese species of the genus are grouped into 3 sections and 6 series inmy classification.  相似文献   

4.
 As a genus Acronema was first proposed by Falconer, but it was only a nomen nudum.  The genus was effectively established by Edgeworth (1851) on the basis of a himalayan species, Acronema tenerum (Wall) Edgew. (= Sison tenerum Wall. 1828). Bentham & Hooker had placed the genus within Pimpinella in 1867.  C. B. Clarke followed the same treatment in the Flora of British India in 1879. The much detailed systematic work of the genus was done by H. Wolff in Engl.  Pflanzenreich (1927).       The chief distinguishing character of the genus lies in the acuminulate of filamen- tous apices of the petals.      At present the genus contains about 23 species chiefly in the himalayan regions and South-west China, many being found in Sichuan, Yunnan and eastern Xizang.       They are usually growing under the shade of forest, roadside and riverside at the altitude 2100—4800 meters.       In this paper 18 species and 2 varieties are presented, of which 5 species, 2 varieties and 1 combinations are considered as new and three arc first recorded fromChina.  相似文献   

5.
The morphological characters in the genus Orobanche were evaluated from the taxonomic point of view.  The author finds that the plants of this genus are relatively similar to each other in respect to characters of vegetative organs, fruits and seeds.  But the differences in the floral structures can be served as a basis for delimitating infrageneric taxa.   The seed coat of 18 species and pollen grains of  6 species were also examined under scanning electron microscope (SEM). They seem to have little significance for distinguishing species.       The result supports G. Beck’s (1930) division of the genus Orobanche into 4 sections, of which 2 occur in China, based on the characters of the inflorescence, bracteoles and calyx. The author considers that some characters, such as anther hairy or not, upper lip of corolla entire or not, lower lip longer or shorter than the upper one, the state of corolla-tube inflec-  tion and the hair type of filaments and plants, are important in distinguishing Chinese species.  A key to the species of Orobanche in China is given.       This genus consists of about 100 species, and is mostly confined to Eurasia, with over 60  species found in Caucasus and Middle Asia of USSR, where may be the mordern  distribu-  tional  centre.        Orobanche L. in China is represented by 23 species, 3 varieties and l forma. As shown in  Table 1, most species (12 species) are found in Xinjiang, which clearly shows a close floristic  relationship between this region and Middle Asia of USSR.  6 species are endemic to China,  of which 4 are confined to the Hengduan Mountains  (Yangtze-Mekong-Salwin divide).        The relationships between this genus and related ones of Orobanchaceae are also discussed.  The author holds the following opinions: the genus Phelypaea Desf. should be considered as a   member of Orobanche L. Sect. Gymnocaulis G. Beck,  the monotypic genus,   Necranthus A.   Gilli endemic to Turkey, is allied with Orobanche L. Sect.  Orobanche, the monotypic genus,   Platypholis Maxim, endemic to Bonin Is. of Japan, is far from Orobanche L. in relation and   should be regarded as a separate genus.        The 11 OTU’s, including all the sections of Orobanche L. and 7 genera of Orobanchaceae,   and 15 morphological characters were used in the  numerical  taxonomic treatment  to  test  the   above-mentioned  suggestions.   After standardization of characters, the correlation matrices were   computerized.  The correlation matrices were made to test the various clustering methods.   At    last the UPGMA clustering method was chosen and its result is shown in a phenogram.  The   result of numerical analysis is basically in accordance with the suggestions.  相似文献   

6.
 When F. A. McClure published the new genus Sinocalamus McClure in 1940, the 4 species he listed are S. latiflorus (Munro) McClure, S. beecheyanus (Munro) Mc- Clure, S. oldhami (Munro) McClure and S. affinis (Rendle) McClure.  After careful examination, the authors of this paper considered that the type species of McClure’s genus S. latiflorus (Munro) McClure should belong to the genus Dendrocalamus Nees, and the other species are of Bambusa Schreber.  Owing to Sinocalamus McClure is not a taxon representative of its type species, but a mixture, it must be rejected as a synonym of Dendrocalamus Nees.  In consequence then, the authors make adjustment to the taxonomic category of the 14 species and 1 variety which have ever been in Sinocalamus McClure.      As for the characters of Lingnania McClure, except that some differences exist in the vegetative parts, the structure of the spikelets is in the main the same as that of Bambusa Schreber.  Consequently, with regard to the systematic relationship, the authors consider it may be more resonable that the rank of Lingnania McClure should be alter- ed to Bambusa Schreber subg.  Lingnania (MeClure) Chia  et H. L. Fung; all the species of Lingnania McClure, except that L. tsiangii McClure should be transferred to Dendrocalamus Nees, should be assignable to Bambusa Schreber subg.  Lingnania (McClure) Chia et H. L. Fung.  相似文献   

7.
木兰科分类系统的初步研究   总被引:10,自引:0,他引:10  
A new system of classification of Magnoliaceae proposed.  This paper deals mainly with taxonomy and phytogeography of the family Magnoliaceae on the basis of external morphology, wood anatomy and palynology.  Different  authors have had different ideas about the delimitation of genera of this family, their controversy being carried on through more than one hundred years (Table I).  Since I have been engaged in the work of the Flora Reipublicae Popularis Sinicae, I have accumulated a considerable amount of information and material and have investigated the living plants at their natural localities, which enable me to find out the evolutionary tendencies and primitive morphological characters of various genera of the family.  According to the evolutionary tendencies of the characters and the geographical distribution of this family I propose a new system by dividing it into two subfamilies, Magnolioideae and Liriodendroideae Law (1979), two tribes, Magnolieae and Michelieae Law, four subtribes, Manglietiinae Law, Magnoliinae, Elmerrilliinae Law and Micheliinae, and fifteen genera (Fig. 1 ), a system which is different from those by J. D. Dandy (1964-1974) and the other authors.      The recent distribution and possible survival centre of Magnoliaceae. The members of Magnoliaceae are distributed chiefly in temperate and tropical zones of the Northern Hemisphere, ——Southeast Asia and southeast North America, but a few genera and species also occur in the Malay Archipelago and Brazil of the Southern Hemisphere. Forty species of 4 genera occur in America, among which one genus (Dugendiodendron) is endemic to the continent, while about 200 species of 14 genera occur in Southeast Asia, of which 12 genera are endemic.  In China there are about 110 species of 11 genera which mostly occur in Guangxi, Guangdong and Yunnan; 58 species and more than 9 genera occur in the mountainous districts of Yunnan.   Moreover,  one  genus (Manglietiastrum Law, 1979) and 19 species are endemic to this region.  The family in discussion is much limited to or interruptedly distributed in the mountainous regions of Guangxi, Guangdong and Yunnan.  The regions are found to have a great abundance of species, and the members of the relatively primitive taxa are also much more there than in the other regions of the world.      The major genera, Manglietia, Magnolia and Michelia, possess 160 out of a total of 240 species in the whole family.  Talauma has 40 species, while the other eleven genera each contain only 2 to 7 species, even with one monotypic genus.   These three major genera are sufficient for indicating the evolutionary tendency and geographical distribution of Magnoliaceae.  It is worthwhile discussing their morphological  characters  and distributional patterns as follows:      The members of Manglietia are all evergreen trees, with flowers terminal, anthers dehiscing introrsely, filaments very short and flat, ovules 4 or more per carpel.  This is considered as the most primitive genus in subtribe Manglietiinae.  Eighteen out of a total  of 35 species of the genus are distributed in the western, southwest to southeast Yunnan. Very primitive species, such as Manglietia hookeri, M. insignis  and M. mega- phylla, M. grandis, also occur in this region. They are distributed from Yunnan eastwards to Zhejiang and Fujian through central China, south China, with only one species (Manglietia microtricha) of the genus westwards to Xizang.  There are several species distributing southwards from northeast India to the Malay Archipelago (Fig. 7).      The members of Magnolia are evergreen and deciduous trees or shrubs, with flowers terminal, anthers dehiscing introrsely or laterally, ovules 2 per carpel, stipule adnate to the petiole.  The genus Magnolia is the most primitive in the subtribe Magnoliinae and is the largest genus of the family Magnoliaceae. Its deciduous species are distributed from Yunnan north-eastwards to Korea and Japan (Kurile N. 46’) through Central China, North China and westwards to Burma, the eastern Himalayas  and northeast India.  The evergreen species are distributed from northeast  Yunnan  (China)  to  the Malay Archipelago.  In China there are 23 species, of which 15 seem to be very primi- tive, e.g. Magnolia henryi, M. delavayi, M. officinalis and M. rostrata, which occur in Guangxi, Guangdong and Yunnan.      The members of Michelia are evergreen trees or shrubs, with flowers axillary, an- thers dehiscing laterally or sublaterally, gynoecium stipitate, carpels numerous or few. Michelia is considered to be the most primitive in the subtribe Micheliinae, and is to the second largest genus of the family.  About 23 out of a total of 50 species of this genus are very primitive, e.g. Michelia sphaerantha, M. lacei, M. champaca,  and  M. flavidiflora, which occur in Guangdong, Guangxi and Yunnan (the distributional center of the family under discussion)  and extend eastwards to Taiwan  of  China, southern Japan through central China, southwards to the Malay Archipelago through Indo-China. westwards to Xizang of China, and south-westwards to India and Sri Lanka (Fig. 7).      The members of Magnoliaceae are concentrated in Guangxi, Guangdong and Yunnan and radiate from there.  The farther away from the centre, the less members we are able to find, but the more advanced they are in morphology.  In this old geographical centre there are more primitive species, more  endemics  and  more monotypic genera. Thus it is reasonable to assume that the region of Guangxi, Guangdong and Yunnan, China, is not only the centre of recent distribution, but also the chief survival centreof Magnoliaceae in the world.  相似文献   

8.
This paper is here presented as a material for a flora of the Chinese grasses.  At the beginning, it chronologically gives a brief historical sketch on the study of the sub- tribe Isachninae.  The category which this group should constitute is here delimited, and its position in the natural system of grass-classification is also discussed.       Secondly it deals with a taxonomic treatment on the genus Isachne which comprises 16 species and 7 varieties in China, amongst which two species (I. hoi and I. hainanensis) and four varieties (I. albens var. glandulifera, I. truncata vars. crispa & maxima, and I. nipponensis var. kiangsiensis) are published here as new to science.  In addition, a new combination, I. hirsuta, (Hook. f.) Keng, f., based upon I. albens var. hirsuta Hook. f., is made here.  The two species (I. ciliatiflora Keng, and  I. tenuis  Keng)  published in Chinese only in the “Flora Illustralis Plantarum Primarum Sinicarum Graimeae 1959”, arehere supplemented with Latin diagnoses for validation.  相似文献   

9.
中国委陵菜属植物研究   总被引:2,自引:0,他引:2  
  相似文献   

10.
 Xizang (Tibet) is rich in Leguminosae flora, comprising 41 genera and 254 species so far known, exclusive of the commonly cultivated taxa (including 11 genera and 16 species). There are 4 endemic genera (with 8 species), 10 temperate genera (with 175 species) and 19 tropical genera (with 46 species) as well as the representatives of those genera whose distribution centers are in East Asia-North  America, Mediterranean and Central Asia.       1.  There are altogether 4 endemic genera of Leguminosae in this region. Accord- ing to their morphological characters, systematic position and geographical distribution, it would appear that Salweenia and Piptanthus are Tertiary paleo-endemics, while Straceya and Cochlianths are neo-endemics. Salweenia and Piptanthus may be some of more primitive members in the subfamily Papilionasae and their allies are largely distributed in the southern Hemisphere.  The other two genera might have been derived from the northern temperate genus Hedysarum and the East Asian-North American genus Apios respectively, because of their morphological resemblance. They probably came into existanc during the uplifting of the Himalayas.       2. An analysis of temperate genera       There are twelve temperate genera of Leguminosae in the region, of which the more important elements in composition of flora, is Astragalus, Oxytropis and Cara- gana.       Astragalus  is a  cosmopolitan  genus comprising 2000 species, with its center distribution in Central Asia. 250 species, are from China so far known, in alpine zone of Southwest and Northwest, with 70 species extending farther to the Himalayas and Xizang Plateau.       Among them, there are 7 species (10%) common to Central Asia, 12 species (15.7%) to Southwest China and 40 species (60%) are endemic, it indicates that the differentia- tion of the species of the genus in the region is very active, especially in the subgenus Pogonophace with beards in stigma. 27 species amounting to 78.5% of the total species of the subgenus, are distributed in this region.  The species in the region mainly occur in alpine zone between altitude of 3500—300 m. above sea-level. They have developed into a member of representative of arid and cold alpine regions.      The endemic species of Astragalus in Xizang might be formed by specialization of the alien and native elements. It will be proved by a series of horizontal and vertical vicarism of endemic species.  For example, Astragalus bomiensis and A. englerianus are horizontal and vertical vicarism species, the former being distributed in southeast part of Xizang and the latter in Yunnan; also A. arnoldii and A. chomutovii, the former being an endemic on Xizang Plateau and latter in Central Asia.      The genus Oxytropis comprises 300 species which are mainly distributed in the north temperate zone. About 100 species are from China so far known, with 40 species extending to Himalayas and Xizang Plateau.  The distribution, formation and differ- entiation of the genus in this region are resembled to Astragalus.  These two genera are usually growing together, composing the main accompanying elements of alpine mea- dow and steppe.      Caragana is an endemic genus in Eurasian temperate zone and one of constructive elements of alpine bush-wood. About 100 species are from China, with 16 species in Xi- zang. According to the elements of composition, 4 species are common to Inner Mon- golia and Kausu, 4 species to Southwest of China, the others are endemic. This not only indicates that the species of Caragana in Xizang is closely related to those species of above mentioned regions, but the differentiation of the genus in the region is obviously effected by the uplifting of Himalayas, thus leading to the formations of endemic species reaching up to 50%.      3. An Analysis of Tropical Genera      There are 19 tropical genera in the region. They concentrate in southeast of Xizang and southern flank of the Himalayas. All of them but Indigofera and Desmodium are represented by a few species, especially the endemic species. Thus, it can be seen that they are less differentiated than the temperate genera.      However, the genus Desmodium which extends from tropical southeast and northeast Asia to Mexio is more active in differentiation than the other genera. According to Oha- Shi,s system about the genus in 1973, the species of Desmodium distributed in Sino-Hima- laya region mostly belong to the subgenus Dollinera and subgenus Podocarpium.  The subgenus Dollinera concentrates in both Sino-Himalaya region and Indo-China with 14 species, of which 7 species are endemic in Sino-Himalaya.  They are closely related to species of Indo-China, southern Yunnan and Assam and shows tha tthey have close con- nections in origin and that the former might be derived from the latter.      Another subgenus extending from subtropical to temperate zone is Podocarpium. Five out of the total eight species belonging to the subgenus are distributed in Sino- Himalaya and three of them are endemic.      An investigation on interspecific evolutionary relationship and geographic distribu- tion of the subgenus shows that the primary center of differentiation of Podocarpium is in the Sino-Himalaya region.      Finally, our survey shows that owing to the uplifting of the Himalayas which has brought about complicated geographic and climatic situations, the favorable conditions have been provided not only for the formation of the species but also for the genus in cer-tain degree.  相似文献   

11.
Shibataea Makino is a genus of Subfam. Bambusoideae, with 8 species, distributed in Southeast China and Southwest Japan.  In China wild plants of the genus are found in Fujian, Jiangxi, Zhejiang, Jiangsu and Anhui provinces, especially in Fujian and Zhejiang. The genus is also cultivated in parks of Guangzhou, Teibei and some other gardens.      Raches of inflorescences in genera Semiarundinaria, Brachystachyum, Phyllostachys and Shibataea have many branches, even secondary branches.  A large bract is often present at the base of each branch, and a prophyll in the axil of the bract in Tribe Shibataeeae Nakai.  Mo- reover, an inflorescence is composed of numerous dense spikelets.  This type of inflorescence may be considered primitive.   The genera Indosasa and Sinobambusa are of more stamens (6 in the former and 3 or 4, 5 in the latter) than in the genera Semiarundinaria and Brachysta- chyum (only 3), and their inflorescences are very simple with fewer spikelets and raches,without the large bract.  This type of inflorescence may be considered more advanced.  相似文献   

12.
13.
藁本属Ligusticum L.属伞形科Umbelliferae芹亚科Apioideae Drude阿米芹族Ammineae Koch。它在阿米芹族中,是一个较进化的类群,是介于阿米芹族与前胡族Peucedaneae DC.之间的一个过渡类型。藁本属全世界60余种。我国现知有34种,占该属种数的二分之一,其中28种及2个栽培变种为我国所特有。本文比较分析藁本属的形态学性状和孢粉学性状,以小总苞片及其相关特征作为该属次级划分的主要依据,将藁本属分为两个类群,并对该属的种类作了增补,对一些种的名称、分布作了补充修订。文中还记载了4个新种。喜马拉雅藁本L.elatum(Edgew.)C.B.Clarke和开展藁本L. thomsonii C. B. Clarke var.evolutior C. B.Clarke,系我国首次记录。  相似文献   

14.
After having examined all specimens of the genus Prenanthes L. of Compositae in the Herbarium of Institute of Botany, Academia Sinica, I find that the classic concept on the genus Prenanthes established by G. Bentham in 1873 has not been held exactly by some of Euro- pean, American, Japanese and Chinese botanists. For example, W. B. Hemsley, S. T. Dunn, A. Franchet, S. Kitamura and C. C. Chang placed plants from China which belong to other groups into the genus; I also find that the classic concept of the genus is not clear.  The present paper makes a revision not only on the classic concept of the genus, but also on its concept assumed by the above-mentionded botanists.      With the combination of numerous (25-35), white or yellow ligular florets, numerous ribs of achenes, Prenanthes alba L. (Nabalus albus (L.) Shih, comb. nov.) is distinctly different from Prenanthes purpurea L., which has the combination of purple, few (5-15) ligular flo- rests and few ribs of achenes.  Nabalus Cass., as a genus established early (1825) by H. Cassini, should be restored.  It is not reasonable to treat Nabalus as a subgenus (E. B. Babcock et al. 1947) or a section (S. Kitamura, 1956) or as a synonym (G. Bentham, 1983) of the genus Preanathes L.       The present author recognizes seven species in the new revised genus  Prenanthes L.  in China, 4 of which are described as new.  In the genus Nabalus Cass.  only one species, N. ochroleuca Maxim., is distributed in Northeast China.       As Lactuca melanantha Franch. (1895), Prenanthes henryi Dunn (1903), P. glandulosa Dunn (1903), Lactuca triflora Hemsl. (1888) (it was transferred to Prenanthes L. by C. C. Chang in 1934), Prenanthes formosana Kitam. (1934) and P. wilsoni Chang (1934) all have campanulate involucres, purple phyllaries, purple dorsi-ventrally compressed achenes, longitu- dinal rids 6-9 on each side of achene truncate and beakless at its apex and pilose tubes of co- rollae, they should be placed neither into the genus Prenanthes with obtusely tri-or pentagonous, subterete achenes and glabrous tubes of corollae, nor into the genus Lactuca with beak achenes. Besides the above-mentioned species misnamed by some of foreign and Chinese botanists, 6 other species also have the same structure in achenes and corollae.  Evidently, they fall into a new genus with the name Notoseris Shih.       The new genus Notoseris Shih of the tribe Lactuceae of Compositae seems to be more re- miniscent of Lactuca L. than of Prenanthes L. emend.       All the 12 species of the genus Notoseris Shih are endemic to China and distributed in the area of south of Yantze River. Of them 6 are new combinations and 6 are described as new.  相似文献   

15.
国产三角瓣花属(茜草科)订正   总被引:1,自引:0,他引:1  
三角瓣花属Prismatomeris Thw.在Hooker(1873)和K.Schumann(1891)的茜草   科分类系统中隶于巴戟族Morindeae Miq.但在 Bremekamp(1966年)的分类系统中,其分类   位置未定。本属的胚根下位,花冠裂片镊合状排列和具针晶等特征与巴戟族相同,但它的花   离生,子房2室,胚珠盾形而着生于子房隔膜上半部等特征则与巴戟族明显不同。  因此,   将本属分立作族并置于Bremekamp所定界的茜草亚科Rubioideae中似乎较合适。  本文还提   供了经挑选的本属10对特征及其分类价值的说明。辨别了两个种:(1)将分布于中国的P.   tetrandra(Roxb.)K.Schum. 修订为 “P.tetrandra  (Roxb.)  K.  Schum. subsp. multiflora   (Ridley,)Y.Z.Ruan”. (2)P.  connata Y.  Z.  Ruan 被记述作新种它的热带新亚种是  P.  connata Y.  Z.  Ruan  subsp.  hainanensis Y.  Z.  Ruan。  相似文献   

16.
本文首次报道了中国特有异叶苣苔属的染色体数目及核型。该属所研究种类的染色体数目均为   2n=18,染色体长度在2.0µm以上,在尖舌苣苔族所报道的染色体中显示出较原始的性状。尖舌苣苔   族的染色体基数可能是x=9。异叶苣苔属的间期核均为复杂型;前期染色体呈渐变型。核型从对称型   向不对称型的演化主要表现在近中部着丝粒,尤其是近端部着丝粒染色体比例的增大。毕节异叶苣苔   W.bljieensis和峨眉异叶苣苔W.tsiangiana var.wilsonii的核型分别为2n=2m+8m+8sm(1sat)和   2n=2m+8m(1sat)+8sm(2sat),较为对称。紫红异叶苣苔W.purpurascens和白花异叶苣苔W.   tsiangiana var. tsiangiana的核型分别为2n=4m+6sm+8st(1sat)和2n=4m+8sm(2sat)+6st,比较   特化。河口异叶苣苔W.hekouensis的核型是2n=4m+10sm(1sat)+4st,处于二者之间。峨眉异叶苣   苔和原变种白花异叶苣苔的核型差异较大,在外部形态方面二者之间的性状变异也间断较大。本文建  议将该变种从白花异叶苣苔W.tsiangiana中移出自成一种,并和毕节异叶苣苔近缘。  相似文献   

17.
鳞毛蕨属的生物系统学研究   总被引:1,自引:0,他引:1  
At the outset the paper begins with a brief discussion of the geographical origin of the genus Dryopteris. With the cytological data so far available the author presumed that the No- rthern Hemisphere and possibly Eurasia is the geographical origin of the genus and that the Eastern Himalayas, China and Japan is the centre of speciation of the genus, and thence has spread to other continents along several routes. He is also of the opinion that the genus  tends to evolve the highest grade of polyploidy where it has existed longest. On the other hand, he pointed out that the production of polyploids may occur most frequently in response to pressures which a group meets in the course of its migration in space and time, with  the  majority  of diploids persisting as relics close to the original centre of diversification.       He then described the progress of the biosystematics of the European and North American Dryopteris, which has been undertaken through a close cooperation among botanists, cytologists and phytochemists of different nations. This team is also looking forward to a cooperation with the Chinese botanists in the study of East Asian species of Dryopteris, so that the relationships of Chinese species and those of other floras can be understood.       The term biosystematics had been invented to mean experimental studies of breeding sy- stems of the species concerned in order to ellucidate their evolutionary relationships.  It stems from the early researches of Professor Irene Manton whose classical book “Problems of Cytology and Evolution in the Pteridophyta” (1950) laid the foundation of Biosystematics. Manton was also the first to introduce the acetocarmine squash  method for staining  chromosomes  in  the spore-mother-cells at meiosis.       The lecture was illustrated with diagrams showing in detail the pairing behaviour of the chromosomes at the metaphase in meiosis and the formation of the polyploidies of different levels.       Besides cytological approach two other techniques have been also applied to the systematic studies of Dryopteris. The first is the comparison of sporoderms  using the scaning  electron microscope, revealing different ornamentations on the pericine. The second is the study of plant chemistry, in particular, that of the phloroglucinoles by thinlayer chromatography.       The remaining far greater part of the paper is devoted to analysing cytologically the Eu- ropean and North American species of Dryopteris in three groups, showing the lines of experi-mental work that has resulted in the understanding of their evolutional relationships.  相似文献   

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