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1.
毛冠菊属系统位置的核形态证据   总被引:3,自引:2,他引:1  
首次记载了毛冠菊属2种4居群的核形态资料。两种植物的染色体间期和前期染色体为复杂型 和中间型。狭舌毛冠菊两居群的染色体数目与核型公式为2n=18=14m+2sm+2st(2SAT);毛冠菊两居 群的染色体数目与核型公式为2n=18=14m+2sm(2SAT)+2st。它们分别代表了整个毛冠菊属的两组 植物,并包含了形态学上最原始的种类,因此,该属的染色体基数可能为x=9。核形态证据表明毛冠菊属放在紫菀族比放在旋覆花族和千里光族中更为合理。  相似文献   

2.
中国荞麦属花粉形态及花被片和果实微形态特征的研究   总被引:6,自引:0,他引:6  
研究了中国荞麦属Fagopyrum Mill.的花粉形态、花被片和果实微形态特征。根据沟膜的有无,花粉可以明显地区分为具沟膜者和不具沟膜者2类。透射电镜下显示,荞麦F. esculentum Moench的花粉外壁分化成两个明显的层次,即外壁外层和外壁内层。其外壁外层由覆盖层及柱状层组成,无基层。对花被片腹面的扫描电镜观察表明,根据细胞形状和表面纹饰,这些种类的花被片可分为3类。对果实表面的扫描电镜观察表明,这些种类的果实纹饰也可分为3类。根据上述结果,讨论了荞麦属的种间关系及花粉形态、花被片和果实一些微观性状的演化趋势。荞麦属的花粉形态极为一致,其外壁纹饰均为细网状,萌发孔为三孔沟,这支持将荞麦属从蓼属中分出独立成属的观点。本文还根据花粉形态特征及花被片和果实微形态特征讨论了国产荞麦属的种间关系,探讨了一些特征的演化趋势。  相似文献   

3.
虾须草属Sheareria (菊科Compositae)是我国特有的单型属.国内学者将其置于向日葵族Helianthereae米勒菊亚族MiUeriinae,而Robinson和Nesom则认为该属应归属于紫菀族Astereae.我们比较该属与向日葵族、紫菀族代表植物种类的微形态学、解剖学和细胞学特征.虾须草S. nana舌片近轴面细胞为线形,具横向条纹,细胞中央纵向隆起,与紫菀族代表种相同或相近,而与向日葵族的代表种中的细胞近圆形、表面具乳突存在显著区别.在舌状花子房壁横切面上维管柬(肋)间部分的结构上,5种向日葵族植物具有如下共同特征:子房壁含3-4层结构,即表皮、下皮层、小细胞区,有的还有薄壁细胞层;表皮与下皮层细胞大小和形态一致,排列整齐.虾须草与5种紫菀族植物的子房壁均只由表皮和薄壁组织组成.虾须草为二倍体,核型公式为2n=2x=18sm.虾须草与紫菀族的染色体基数均为x=9,而和向日葵族普遍存在的染色体基数x=10不同.所有的证据都表明虾须草属应置于紫菀族,而不是向日葵族中.  相似文献   

4.
毛冠菊属的花粉形态和结构及其系统学意义   总被引:1,自引:0,他引:1  
对国产菊科特有属的花粉形态和结构进行了光学显微镜、扫描电镜和透射电镜的观察和研究。该属的花粉可以分为圆球形、扁球形和长球形三种类型。种之间的花粉差异主要表现在大小、形状和外壁纺饰的细微变化等方面。与紫菀族、竿里光旋和旋覆共族三个族的代表种的花粉特征进行对比分析,并结合其它生物演化证据,可得取以下结论:(1)支持and-Mazzetti的分类意见,毽炙属应归于紫族中;(2)毛冠菊属的花粉可划分为圆球  相似文献   

5.
刘建全 《武汉植物学研究》2000,18(6):461-465,T002,T005
研究了国产菊科千里光族款冬亚族及其相关类群11属15种植物的花粉超薄结构。研究类群的花粉超薄结构可分为2类:“千里光型”和“向日葵型”。多榔菊属、大吴风草属和毛冠菊属为“向日葵型”,其余种类均为“千里光型”。根据花粉超薄结构类型,结合其它有关方面的研究,认为大吴风草属与橐吾属并不近缘,而毛冠菊属可能接近于紫菀族。  相似文献   

6.
研究了国产菊科千里光族款冬亚族及其相关类群 1 1属 1 5种植物的花粉超薄结构。研究类群的花粉超薄结构可分为 2类 :“千里光型”和“向日葵型”。多榔菊属、大吴风草属和毛冠菊属为“向日葵型”,其余种类均为“千里光型”。根据花粉超薄结构类型 ,结合其它有关方面的研究 ,认为大吴风草属与橐吾属并不近缘 ,而毛冠菊属可能接近于紫菀族。  相似文献   

7.
刘建全 《植物研究》2001,21(1):11-17
所研究的东亚款冬亚族及其相关类群的花部微观性状主要包括:花药顶端不育组织、花药药室内壁、花药基部、花药领、花柱分枝顶端、花柱毛被、花柱分枝内表面构型和果柄细胞列数等。此外, 根据所获证据, 讨论了款冬亚族花部微观性状的演化趋势。花部微观性状研究表明:毛冠菊属似乎应作为紫菀族中的一个孤立属;狗舌草亚族与千里光亚族和款冬亚族相比, 似乎是一过渡类群;东亚款冬亚族13 个属似可划分为6 个自然属群。  相似文献   

8.
刘建全 《木本植物研究》2001,21(1):11-17,T001,T002,T003,T009
所研究的东亚款冬亚族及其相关类群的花部微观性状主要包括:花药顶端不育组织、花药药室内壁、花药基部、花药领、花柱分枝顶端、花柱毛被、花柱分枝内表面构型和果柄细胞列数等。此外,根据所获证据,讲座了款冬亚族花部微观性状的演化趋势。花部微观性状研究表明,毛冠菊属似乎应作为紫菀族中的一个孤立属、狗舌草亚族与千里光亚族和款冬亚族相比,似乎是一过渡类群;东亚款冬亚族13个属似可划分为6个自然属群。  相似文献   

9.
利用扫描电子显微镜对禾本科梯牧草属及其近缘属共17属35种2变种植物的叶片上下表皮微形态特征进行了研究。结果显示,梯牧草属植物叶片上下表皮脉间长细胞都为长筒形或长菱形,细胞壁平直或弯曲,脉上硅细胞结节形,气孔副卫细胞平行形,脉上刺细胞常见,脉间偶见或缺失,无乳突,无微毛;同时,根据叶表皮微形态性状构建了系统发育树,结果表明梯牧草属与早熟禾族聚为一支,显示其亲缘关系较近,而与燕麦族、剪股颖族和虉草族的亲缘关系则相对较远,因此叶表皮微形态证据支持将梯牧草属置于早熟禾族中。  相似文献   

10.
马兰属花粉形态的研究   总被引:5,自引:0,他引:5  
王静  张小平 《植物研究》1999,19(1):34-39
本文对马兰属9种3变种1变型的花粉形态进行了光学显微镜和扫描电子显微镜的观察和初步比较研究。花粉粒为近球形,极面观三裂圆形。具三孔沟。外壁表面具刺状纹饰。不同种类花粉大小和外壁表面纹饰不同,可以作为区分种类的依据或参考。据此,将马形马兰上升为种,羽叶马兰和羽裂叶毡毛马兰合并,甘川紫菀和高茎紫菀划归马兰属。  相似文献   

11.
All taxa endemic to the Qinghai-Tibet Plateau are hypothesized to have originated in situ or from immediately adjacent areas because of the relatively recent formation of the plateau since the Pliocene, followed by the large-scaled biota extinction and recession caused by the Quaternary ice sheet. However, identification of specific progenitors remains difficult for some endemics, especially some endemic genera. Nannoglottis, with about eight species endemic to this region, is one such genus. Past taxonomic treatments have suggested its relationships with four different tribes of Asteraceae. We intend to identify the closest relatives of Nannoglottis by evaluating the level of monophyly, tribal delimitation, and systematic position of the genus by using molecular data from ndhF gene, trnL-F, and ITS region sequences. We find that all sampled species of Nannoglottis are a well-defined monophyly. This supports all recent taxonomic treatments of Nannoglottis, in which all sampled species were placed in one broadly re-circumscribed genus. Nannoglottis is most closely related to the Astereae, but stands as an isolated genus as the first diverging lineage of the tribe, without close relatives. A tentative relationship was suggested for Nannoglottis and the next lineage of the tribe was based on the ITS topology, the "basal group," which consists of seven genera from the Southern Hemisphere. Such a relationship is supported by some commonly shared plesiomorphic morphological characters. Despite the very early divergence of Nannoglottis in the Astereae, the tribe must be regarded to have its origin in Southern Hemisphere rather than in Asia, because based on all morphological, molecular, biogeographical, and fossil data, the Asteraceae and its major lineages (tribes) are supposed to have originated in the former area. Long-distance dispersal using Southeast Asia as a steppingstone from Southern Hemisphere to the Qinghai-Tibet Plateau is the most likely explanation for this unusual biogeographic link of Nannoglottis. The 23-32-million-year divergence time between Nannoglottis and the other Astereae estimated by DNA sequences predated the formation of the plateau. This estimation is further favored by the fossil record of the Asteraceae and the possible time of origin of the Astereae. Nannoglottis seems to have reached the Qinghai-Tibet area in the Oligocene-Eocene and then re-diversified with the uplift of the plateau. The molecular infragenetic phylogeny of the genus identifies two distinct clades, which reject the earlier infrageneric classification based on the arrangement of the involucral bracts and the length of the ligules, but agree well with the habits and ecological preferences of its current species. The "alpine shrub" vs. "coniferous forest" divergence within Nannoglottis was estimated at about 3.4 million years ago when the plateau began its first large-scale uplifting and the coniferous vegetation began to appear. Most of the current species at the "coniferous forest" clade of the genus are estimated to have originated from 1.02 to 1.94 million years ago, when the second and third uprisings of the plateau occurred, the climate oscillated and the habitats were strongly changed. The assumed evolution, speciation diversity, and radiation of Nannoglottis based on molecular phylogeny and divergence times agree well with the known geological and paleobotanical histories of the Qinghai-Tibet Plateau.  相似文献   

12.
Floral microcharacters of the genus Chrysolaena H. Rob. (Vernonieae, Asteraceae) were analysed in detail for the first time in order to evaluate the taxonomic position of conflictive species in the group. The results were also compared with studies carried out in species of related genera. In addition to distinctive microcharacters previously studied in some species of the genus, other characters such as trichome types of the corolla, style, anthers and cypselae have been analysed for the first time. The presence of glandular apical appendage and cypselae are common characteristics among species Chrysolaena. In addition to these, this study shows that presence of glands on the style and corollas is another consistent characteristic in the genus. However, the absence of basal stylar node would not be a diagnostic character since this varies widely among species. The results indicate that most of the microcharacters of Chrysolaena analysed are quite consistent in the genus, but they are no more consistent than the pollen morphology (type 'C') and chromosome base number (x = 10). Until now, these last two features would be most useful for separating Chrysolaena from the related genera Lessingianthus and Lepidaploa. At species level, the results show that related species can be distinguished by the different combinations of floral microcharacters. The value of microcharacters could be increased if they are combined with other morphological, cytological, and palynological data.  相似文献   

13.
Anderberg, A. A. & Karis, P. O. 1995. Psednotrichia , a genus of the tribe Senecioneae hitherto misplaced in the Astereae (Asteraceae). — Nord. J. Bot. 15: 375–379. Copenhagen. ISSN 0107–055X.
The tribal position for the little known genus Psednorrichia , is established. This monotypic genus, hitherto placed in the tribe Astereae, is a congener of Xyridopsis of the tribe Senecioneae (Asteraceae). The two species of Xyridopsis are here transferred to Psednotrichia and the new combinations P. xyridopsis and P. newtonii are made. A brief discussion of the morphology of the genus, and its systematic position within the tribe Senecioneae is provided.  相似文献   

14.
The present paper is an attempt to throw some light on two Composite genera, Cavea W. W. Smith et Small and Nannoglottis Maxim., of which the generic features and the systematic position were heretofore rather badly known. Cavea, a monotypic genus based upon Saussurea salwinensis Drumm., was described by W. W. Smith and Small as monocious. From the ample material now in our command, it is found that the genus is either monocious and dioecious, the capitula in the latter case being homogamous. The individuals exclusively provided with sterile flowers are usually smaller in size, sometimes even stemless. Such repartition of sexes was known in the subtribe Plucheinae (tribe Inuleae), to which W. W. Smith and Small were correct to ascribe their genus. Nannoglottis was considered by Maximovicz as un abnormal genus of the tribe Inuleae, having heterogamous capitula with one series of peripheric fertile ligulate pistillate flowers. Having examined the type specimen of N. carpesioices Maxim. and the extensive collection from Kansu and Tsinghai, we incline to say that the genetic characters as discerned by Maximovicz are doubtlessly due to his inaccurate observation. The flowers of Nannoglottis are in fact trimorphous, of which the pistillate ones are 2-3-seriate, the outer being shortly ligulate and the inner, short-tubulate with truncate apex. Handel-Mazzetti, much later, indicated that, in another species, the pistillate flowers are 2-3-seriate, but no mention was made about the inner tubulate pistillate flowers. Franchet, appearing to be unware of Maximovicz's genus, founded his Stereosanthus Franch. and considered it as a genus intermediate between the tribes Inuleae and Senecioneae. The genus was misinterpreted by Franchet as having dimorphous flowers, the pistillate ones being all ligulate. Curious enough, one of the major generic features, viz., the presence of inner tubulate pistillate flowers, was neglected by all early botanists and was first recognized by Handel-Mazzetti fourty years later. However, Handel-Mazzetti was still unacquainted with the characters of Nannoglottis and proposed therefore his new genus Vierhapperia Hand.-Mzt. on the reason that the flowers are trimorphous. Moreover, he compared his genus with Conyza L. and Erigeron L. of the tribe Astereae, but the characters marked by him appear not to be different from those of Nannoglottis. From the above morphological comparaison, it is evident that Nannoglottis and two other genera in question possess in common important characters in the general appearance, the flower-forms and the structure of achenes and pappus. The differences in the disposition of involucral bracts and the length of ligules are criteria good for separating species, but can hardly be regarded as sufficient for generic delimitation. Moreover, these three genera are almost similar in their geographical distribution. These points are adequate to warrant that Stereosanthus and Vierhapperia are in reality congeneric with Nannoglottis. Nannoglottis appears to have been correctly placed by Hoffmann in the subtribe Senecioninae (tribe Senecioneae) though in that subtribe it finds no close relatives. On account of the outstanding characters of the genus, a further study of its systematic position is required. The present paper is brought to close by a tentative scheme of classification of the genus so amplified, of which two sections, namely, sect. Stenolepis Ling et Y. L. Chen (Stereosanthus Franch., p. p. min.) and sect. Nannoglottis (Stereosanthus Franch., p. p.maxim.; Vierhapperia Hand.-Mzt.), altogether including 9 species, are being proposed. Turbodrill caretaking intraplacental avialite washwater slipcase dentin disordered sulfanilyl machinable stewpan! Netherward pressbodies horror abscissa, keratosis frieze. 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Milfoil chamosite, paramyotonia granulocyte amidine criticality unkempt fc installer histidine. Decorative.   相似文献   

15.
在光镜和扫描电镜下观察了假瘤蕨属2系、5亚系的24种植物的叶表皮。结果表明,叶表皮细胞形状不规则,垂周壁波曲状。下生气孔,气孔类型有极细胞型、共环极细胞型、腋下细胞型、聚腋下细胞型和不规则型,常伴生出现。在扫描电镜下,叶表皮气孔器外拱盖内缘为浅波状、少平滑;一些种的保卫细胞两端有“T”型加厚;角质膜波状有条纹,有时附有颗粒。叶表皮的一些特征对该属部分种的区分有一定的参考价值。叶表皮的微形态特征,如气孔器类型和垂周壁类型特征不能用来界定假瘤蕨属的系和亚系。  相似文献   

16.
Membranous ligules of 49 grass species, representing ten tribes, were anatomically studied using light, fluorescence and transmission electron microscopy. Great variety in ligule abaxial surface anatomy was found but internally all ligules so studied possess a tripartite structure of two uniseriate epidermes enclosing a mesophyll tissue of varying thickness. Chloroplasts were present in most of the ligules (where this feature was determined) supporting the view that this is a photosynthetic leaf organ. Of the 36 species examined by fluorescence microscopy eight showed evidence of having a gland-like adaxial epidermis with numerous mitochondria, dictyosomes, strands of rough endoplasmic reticulum and fibrillar material within the periplasmic space next to the outer tangential wall. Existing hypotheses of ligule function are discussed in the light of these anatomical results, and a new hypothesis is proposed.  相似文献   

17.
在光镜和扫描电镜下观察了假瘤蕨属2系、5亚系的24种植物的叶表皮。结果表明,叶表皮细胞形状不规则,垂周壁波曲状。下生气孔,气孔类型有极细胞型、共环极细胞型、腋下细胞型、聚腋下细胞型和不规则型,常伴生出现。在扫描电镜下,叶表皮气孔器外拱盖内缘为浅波状、少平滑;一些种的保卫细胞两端有“T”型加厚;角质膜波状有条纹,有时附有颗粒。叶表皮的一些特征对该属部分种的区分有一定的参考价值。叶表皮的微形态特征,如气孔器类型和垂周壁类型特征不能用来界定假瘤蕨属的系和亚系。  相似文献   

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