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中国委陵菜属植物研究   总被引:2,自引:0,他引:2  
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苹果属植物一新种   总被引:1,自引:0,他引:1  
Malus daochengensis C. L. Li (Rosaceae) is described  as new  from Sichuan Province, China.  相似文献   
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蔷薇科原始属植物叶表皮解剖及其系统学意义   总被引:1,自引:0,他引:1  
本文研究了蔷薇科原始的六个属的代表种的表皮结构。发现在Lyonothamus,Exochorda,     Lindleya和Vauquelinia属中气孔分布于下表面;在最原始的Kagneckia属和与之最接近     的Quillaja属中,除个别种外,气孔在叶表两面分布。它们的气孔类型分化较复杂,有5种类     型,即无规则型(Anomocytic)、辐射型(Actinocytic)、轮列型(Cyclocytic)、平列型(Paracytic)     和四细胞型(Staurocytic)。同时还发现在Kagneckia,Quillaja,Lindleya和Exochorda 4个     属中气孔组成有多型现象,即在叶表皮中同时存在有2-3种气孔类型;在Vauquelinia属和     Lyonothamus属中主要为一种类型气孔组成;尤其是在Lyonothamus属中,气孔集生成块,其     间没有任何表皮细胞间隔,保卫细胞下陷,副卫细胞在表面联合加厚,成为坛状气孔,这在蔷薇     科中十分独特。  表皮的形态结构研究证据支持了得自细胞学上的证据(Goldblatt 1976),    由Hutchinson(1964)定义的蔷薇科原始的Trib. Quillajeae族,是一个不自然的类群。  相似文献   
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本文评述了分支系统分析中最简原理或简约性在系统发育推论中的应用和存在的问题。在系统   发育推论中使用简约性存在的主要问题在于,既无法获得最简约的系统树也不一定得到一个单一的解   决办法。基于此,本文作者接受了Hennig用衍生性状来判断生物之间相似性的同时,用近代大多数   生物系统学家接受的进化论各项原理代替Popper的简约性原理,以寻求单一的解决办法和获得确定   性的结果为目标,提出了一个新的分支系统分析方法——中值淘汰法,用以研究系统发育。这个方法除   了使用衍生性状来判断生物类群之间的亲缘关系外,还强调包括原始的也包括衍生性状在内的性状镶   嵌组合在决定分支和辨别分类群过程中的作用。  相似文献   
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 We have described a new genus Taihangia, collected from, the south part of Taihang Mountain in northern China. At the same time, comparative studies on Taihangia with its related genera have been made in various fields including external morphology, anatomy of carpels, chromosome and pollen morphology by light, scanning and transmission electron microscope. In addition, isoperoxidases of two varietier were analysed by means of polya-crylamide gel slab electrophoresis. The preliminary results are as follows:       Morphology: The genus Taihangia is perennial and has simple leaves, occasionally with 1—2 very small reduced lobes on the upper part of petiole; flowers white, andromo- noecious and androdioecious, terminal, single or rarely 2 on a leafless scape; calyx and cpicalyx with 5 segments; petals 5; stamens numerous; pistils numerous, with pubescent styles, spirally inserted on the receptacle in bisexual flowers, but with less number of abortive and glabrous pistils in male flowers.       In comparison with the related genera such as Dryas, Geum, Coluria and Waldsteinia, the new genus has unisexual flowers and always herbaceous habit indicating its advanced feature but the genus has a primitive style with thin and short hairs as compared with the genus Dryas which has long, pinnately haired styles, a character greatly facilitamg anemo-choric dissemination. The styles of Taihangia are slender and differ from those of the ge-nus Geum which are articulate, with a persistent hooked rostrum, thus adapting to epizo-ochoric dissemination to a higher degree.       The anatomy of carpels shows the baral position of ovules in the genus Taihangia like those in other related genera such as Dryas, Geum, Acomastylis, Coluria and Waldsteinia. This suggests that the new genus and its related ones are in a common evolutionary line as compared with the other tribes which have a pendulous ovule and represent a separate evolutionary line in Rosaceae. Dorsal and ventral bundles in carpels through sections are free at the base. Neither fusion, nor reduction of dorsals and vertrals. are observed. This shows that the genus Taihangia is rather primitive.       Somatic chromosome: All the living plants, collected from both Honan and Hopei Provinces were examined. The results show that in these plants the chromosome number is 2n= 14, and thus the basic number of chromosome is x=7. Such a diploid genus is first found in both anemochoric and epizoochoric genera. Therefore, in this respect Taihangia is primitive as compared with herbaceous polyploid genus Geum and related ones.      Pollen: The stereostructure shown by scanning electron microscope reveals  that  the pollen grains of the genus Taihangia are ellipsoid and 3-colporate. There are two types of exine sculpture. One is rather shortly striate and it seems rugulate over the pollen surface; the other is long-striate. The genus Dryas differs in having only short and thick striae over the surface. The genus is similar to the genera Geum, Coluria and Waldsteinia in colpustype, but differs from them in that they all have long, parallel striae which are distributed along the meridional line.       In addition, under transmission electron microscope, the exine in the Taihangia and related genera Acomastylis, Geum, Coluria, Waldsteinia and Dryas has been shown to be typically differentiated into two distinct layers, nexine and sexine. The nexine, weakly statined, appears to consist of endoxine with no foot-layer, in which the columellae are fused, and which is thicker beneath the apertures. The sexine is 2-layered, consisting of columellae and tectum. Three patterns of tectum can be distinguished in the tribe Dryadeae: the first, in the genera Taihangia, Acomastylis, Geum, Coluria and Waldsteinia, is tectate-imperforate, with the sculpturing elements both acute and obtuse at the top and broad at the base; the second, in the genus Dryas, is semitectate, with the sculpturing elements shown in ultrathin sections rod-like and broader at the top than at the base or as broad at the top as at the base, and the third, tectate-perforate, with the sculpturing elements different in size. From the above results, the herbaceous groups and woody ones  have palynologically evolved in two distinct directions, and the genus Taihangia is related to other herbaceous genera such as Acomastylis, Geum, Coluria and Waldsteinia, as shown in the electron microphotographs of ultrathin sections. The genus Taihangia, however, is different from related herbaceous genera in that the pollen of Taihangia is dimorphic, i.e. in addition to the above pattern of pollen another one of the exine in Taihangia is rugulate, with the sculpturing elements shown in the ultrathin sections being obtuse or emarginate and nearly as broad at the top as at the base.      The interesting results obtained from the comparative analysis of morphology, ana- tomy of carpels, chromosome countings, microscopic and submicrosocopic structures of pollen may enable us to evaluate the systematic position of Taihangia and to throw a new light on evolution of the tribe Dryadeae. It is well known that the modes of dissemination of rosaceous fruits play an important role in the expansion and evolution of the family. The follicle is the most primitive and the plants with follicles, like the Spiraeoideae, are mostly woody and mesic, while the achene, drupe and pyrenarium are derived. In Rosoideae  having a achene is a common feature. Particularly in the tribe Dryadeae, which is distinguished from the other related tribes by having orthotropous ovules, the methods of dissemination of fruits have developed in three distinct specialized directions: anemochory with long, plumose styles (e.g. Dryas), formicochory or dispersed by ants or other insects, with the deciduous styles (e.g. Waldsteinia and Collria),and epizoochory with the upper deciduous stigmatic part and the lower persistent hooked rostrum, an  adhesive organ favouring  epizoochory dissemination (e. g. Geum and related taxa). Taihangia is a genus endemic to mesophytic forest area of northern China. Due to its narrow range and specific habit as well as pubescent styles, neither perfectly adapted to anemochory nor to epizoochory, the genus  Taihangia might be a direct progeny of the ancestry of anemochory. Maintaining the diploidy and having an ntermediate sculptural type of pollen, the new genus might probably represent a linkage between anemochory and zoochory (including epizoochory and dispersed by ants).       Experimental evidence from isoperoxidases shows the stable zymograms of root and roostoks. The anodal isozyme of T. rupestris var. rupestris may be divided into 6 bands: A, B, C, D, E, F, and T. rupestris var. ciliata into 4 bands: A, B, C, G. The two varietiesof the species share 3 bands: A, B, C. However, D, E and F bands are characteristic of var. rupestris and G band is limited to var. ciliata. As far as the available materials are concerned, the analysis of isoperoxidases supports the subdivision of the species into two varieties.  相似文献   
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葡萄属植物花粉形态的研究   总被引:2,自引:0,他引:2  
 利用扫描电子显微镜对葡萄属Vitis L.37个类群(包括32种、1亚种和4变种)以及其近缘属麝香 葡萄属Muscadinia(Planch.)Small一种植物的花粉进行了观察,结果表明,葡萄属植物的花粉形态特征 在区别并鉴定属下的种类时有较大价值,但对种以上的分类以及研究系统演化无多大意义。葡萄属植 物的花粉形态特征可以分为4类:(1)花粉粒扁球形或圆球形(P/E值为O.97-1.08),沟较宽,可见被有 较密颗粒状突起的沟膜,属于该类的有紫葛V.coignetiae Pull.ex Planch.;(2)花粉粒长球形至近长圆球 形(P/E值为1.25~1.76),沟较宽,可见有较疏颗粒状突起的沟膜,该类型包括了庐山葡萄V.hui Cheng 等共10种1亚种3变种;(3)花粉粒长圆球形(P/E值为1.87~2.1),沟边缘紧靠合呈直线状,但在赤道 轴萌发孔处沟边缘分开呈菱形,该类型有秋葡萄V.romanetii Roman du Caill.ex Planch.和锈毛刺葡萄V. davidii(Roman du Caill.)Foex.var.ferruginea Merr.et Chun等1种1变种;(4)花粉粒长球形或超长球形 (P/E值为1.30~2.0),沟边缘紧靠成直线状,麝香葡萄Muscadinia rotundifolia(Michx .)Small等21种的花粉属于此类型。  相似文献   
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