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Pollen of the scrophulariaceous genera Melosperma and Monttea was studied with light and scanning electron microscopy. Both have single, radiosymmetric, isopolar, trizoniaperturate pollen grains with usually ruptured colpus membranes, tectate-perforate to semitectate exines with a columellate interstitium and pitted or perforate nexines. Intergeneric differences in pollen morphology are established based on the differential correlation of sculpturing characters. Comparisons of the pollen of Melosperma and Monttea with that of the tribe Minuleae sensu stricto reveals no difference in the case of Melosperma and the existence of intermediate morphologies and “reticulate” similarities in the case of Monttea; the taxonomic significance of this morphological intergradation is considered. The transfer of Oxycladus aphyllus to Monttea is consistent with the pollen evidence, but proposed affinities between Monttea and tribe Antonieae of the Loganiaceae are not supported.  相似文献   

3.
国产含羞草科一些属花粉形态的研究   总被引:1,自引:0,他引:1  
利用光镜及电镜观察了中国含羞草科金合欢属、合欢属、棋子豆属、围诞树属、朱缨花属、心叶合欢属等6属37种(含变种)植物的花粉形态,对其花粉大小,外壁纹饰进行了比较分析。结果表明它们均为16合花粉(除薄叶围诞树Aberama utile为8合花粉外),在分类上无多大价值;而花粉大小及外壁纹饰却有一定分类意义。表现为:金合金欢属花粉较小,直径为25-30μm,很容易区别;其余属花粉直径均在50μm以上。  相似文献   

4.
Pollen of 53 species of Dilleniaceae and Actinidiaceae was examined by light microscopy, scanning electron microscopy, and a selected group in transmission electron microscopy. Dilleniaceae pollen ranges from tricolpate, tricolporate, tetracolpate, and incipiently inaperturate. Tricolpate types occur only among the Old World subfamily Dillenioideae and the compound aperturate (3-colporate) condition is restricted to the subfamily Tetraceroideae. Within the Dilleniaceae the tricolpate pollen type with elongated apertures is considered primitive, having given rise to the 3-colporate and 4-colpate conditions. The striking pollen dimorphism in the Neotropical species of Tetracera, all of which are androdioecious, is documented; however, in contrast to previous reports, pollen from bisexual flowers appears to be incipiently inaperturate and not pantoporate. The inaperturate condition is interpretated as an early stage in the evolution of outcrossing. Pollen morphology does not support a close relationship between Dilleniaceae and Actinidiaceae. Pollen morphological differences that can be noted between these families are: tectum complete and predominantly psilate or psilate-granular in Actinidiaceae, tectum incomplete, punctate to reticulate in Dilleniaceae; an equatorial bridge of ektexine over the endoaperture usually present in Actinidiaceae, absent in Dilleniaceae; columellae reduced in Actinidiaceae, columellae usually well-developed in Dilleniaceae. Pollen morphology does not argue against a close relationship between Actinidiaceae and Theaceae.  相似文献   

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Scanning and transmission electron microscopy of pollen grains of 29 species, representing the ten extant genera of Cycadales, has provided valuable insight into their relationships. Pollen grains of these taxa are boat-shaped, monosulcate, and bilaterally symmetrical. They range from narrowly to widely elliptical or subcircular when viewed distally, and have an exine surface of psilate, foveolate, or fossulate. Pollen wall ultrastructure of Cycadales is typically tectate with alveolate∗∗∗spongy exine. The nexine is laminated in all genera. Nexine 1 (footlayer) is present in most species as a thin and often discontinuous layer. There is consistent variation in thickness of the sporoderm layers among the genera but relative uniformity within them. Pollen characteristics are well correlated with macro- and micromorphological features, chromosome numbers, geographical distribution, and postulated pollination mode. A close affinity between Encephalartos, Lepidozamia, and Macrozamia is recognized. Pollen characteristics of the genus Bowenia show some similarity with those of the latter group. Except for two species of Macrozamia which are narrowly elliptic, all of the genera have widely elliptic pollen and share a psilate exine surface and the thinnest sexine with nearly identical arrangement of alveoli. Pollen grains of the species in the genus Dioon exhibit a unique morphology but are more similar to Stangeria than they are to those of taxa in Zamiaceae. The circular outline of the grains and the foveolate exine surface are characters shared by these two genera, but several morphological features distinguish Dioon from Stangeria. Ceratozamia and Zamia share a widely elliptic shape, foveolate exine surface and nearly identical sexine, as well as morphological features and chromosome numbers. They differ from Microcycas in sexine thickness, gross morphology and chromosome numbers. The pollen grains of Cycas circinalis and C. revoluta differ in size and structure of the sexine from all other genera and from each other, substantiating their distinct subgeneric delimitations.  相似文献   

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The pollen morphology and tapetal membranes of 17 species of Trillium from North America have been examined by scanning and transmission electron microscopy. The pollen grains of the genus are consistently spherical and inaperturate. The exine is unstratified and ultra-thin. Five types of exine structure are recognized, namely, echinate-, corrugate-, granulate-, verrucate- and spinulate-type, based on the variations in the components of the exine. The granulate-type is the most common and is divided into six subtypes. The features of tapetal membranes also vary in relation with the variation of the exine structures. This study demonstrates the potential of palynological evidence in assessment of taxonomic relationships within the genus.  相似文献   

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芒苞草属的群落学特征和花粉形态   总被引:3,自引:1,他引:3  
本研究表明芒苞草(Acanthochlamys bracteata)的花粉形态与石蒜科、鸢尾科完全不同。经请教吴征镒教授,他在来信中认为芒苞草应“属于在中国(乃至东亚)未曾记录过的一个老科——翡若翠科Velloziaceae”,横断山区一个可能是特有的单种属,分布在干旱河谷灌丛、稀疏针叶林以及亚高山嵩草草甸中。  相似文献   

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Comparative morphological studies of woody Ranales have established the primitive status of the group and hence their key place in angiosperm phylogeny. Significant advances in our knowledge of some ranalian families have been made in recent years. An attempt is made in the present review to bring together a range of morphological data (vegetative and floral anatomy, palynology and embryology) on the Ranales (sensu lato), with particular reference to research work published after the publication of Eames's (1961) book, and to discuss the relationships of the families. Recent ontogenetic studies have shown that the carpel of Drimys is ascidial and not conduplicate as earlier suggested. The inclusion of Degeneria in the Winteraceae is not supported by morphological data. Melville's gonophyll theory has been shown to be inapplicable to the magnoliaceous flower. The pollen of Schisandra is interpreted as derived and specialized rather than primitive as previously supposed. The removal of Schisandra from Magnoliaceae is upheld by morphological evidence. Recent morphological studies do not support a close relationship between Schisandraceae and Illiciaceae suggested by earlier authors. The Canellaceae shows similarities to Winteraceae, Magnoliaceae, Illiciaceae, Eupteleaceae and Myristicaceae. Transitional types of division of pollen mother cells found in Winteraceae, Schisandraceae and Annonaceae and their probable phylogenetic significance have been discussed. The Annonaceae, Winteraceae, Degeneriaceae, Magnoliaceae, Schisandraceae and Cercidiphyllaceae share several embryological features in addition to similarities in floral structure. Ruminate endosperm is regarded either as an archaic feature retained in some taxa or as a later and parallel development in others. Thus its value in assessing relationships seems to be doubtful. Myristicaceae has been shown to be closely related neither to the the Annonaceae nor to the Lauraceae. The suggested relationship of Eupomatiaceae to Annonaceae is not supported by palynology. Floral cortical vascular systems in Magnoliaceae, Annonaceae, Calycanthaceae and Myristicaceae have been compared and it is concluded that they may be vestigial structures. A great deal of similarity has been found between Lauraceae and Calycanthaceae in wood, node, flower structure and embryology. Further floral anatomical evidence has been adduced to support the removal of Scyphostegia from Monimiaceae. The Hernandiaceae show similarities to some members of Monimiaceae while the Gyrocarpaceae resemble the Lauraceae, Gomortegaceae and certain other genera of Monimiaceae. Available evidence from wood and floral anatomy and embryology indicates close relationships among Lauraceae, Monimiaceae and Hernandiaceae. Vegetative and floral anatomical and embryological data seem to indicate a place for the Chloranthaceae in the ranalian complex. Recent anatomical studies in the Nymphaeaceae show that the floral structure is of a primitive type with similarities to the woody Ranales. Available morphological evidence is considered inadequate to express an opinion on the splitting of the family. Ceratophyllaceae is regarded as a highly reduced ranalian family derived most probably from a nymphaeaceous stock. The gynoecium in Berberidaceae is interpreted as monocarpellate. No evidence has been found to support the tricarpellate view. Berberidaceae, Lardizabalaceae and Menispermaceae share several embryological features, while at the same time showing evidence of specialization, each in its own way. Thus they might have arisen from a common stock and early diverged along different lines. The occurrence of several types of embryo sac in Ranunculaceae may well be an indication of specialization, but their probable taxonomic value, if any, is not yet clear. The occurrence of numerous primitive features in Paeonia has been suggested as an argument for its retention in the Ranales. No evidence has been found to preclude the inclusion of Dilleniaceae in the Ranales. On the other hand, as opposed to similarities in wood and pollen characters between Dilleniaceae and Theaceae, floral anatomical and embryological features offer a sharp contrast between the two. The Ranales are believed to be polyphyletic. It has been tentatively suggested that two major phyletic lines may be recognized in each of the woody and herbaceous series: the magnolialian and lauralian lines in the former and the nymphaealian and berberidalian lines in the latter.  相似文献   

10.
东北杜鹃花科4属植物花粉形态的研究   总被引:4,自引:0,他引:4  
利用光学显微镜和扫描电子显微镜对东北杜鹃花科甸杜属(Chamaedaphne Moench.)、杜香属(Ledum Linn.)、松毛翠属(Phyllodoce Salisb.)、越橘属(Vaccinium Linn.)4属6种, 1变种的花粉形态进行了观察和比较研究。以上4属花粉粒均为四合花粉。四合花粉呈正四面体排列。花粉粒近球形。每粒花粉均具3沟,在四合花粉粒上,相邻花粉粒上的沟相接,有些种可见沟内的萌发孔。光镜下可见花粉外壁为内外两层,厚度约相等。不同属种的花粉粒在大小上有区别,花粉粒平均直径为34.0~43.7μm。在扫描电镜下观察可见不同的种花粉表面具有不同的纹饰。为分类学提供了孢粉学方面的证据。  相似文献   

11.
Drugg , Warren S. (California Res. Corp., La Habra.) Pollen morphology of the Lennoaceae. Amer. Jour. Bot. 49(10): 1027–1032. Illus. 1962.—The family Lennoaceae contains 3 genera: Pholisma, Lennoa, and Ammobroma. The pollen of Pholisma is 4-colporate with less common 3- and 5-colporate grains. Lennoa pollen is 3-colporate with rare 4-colporate examples. All Ammobroma pollen is 3-colporate. Pollen of both Lennoa and Ammobroma exhibits sexine thinning in the mesocolpia with resultant depressions. This feature is lacking in Pholisma. Sculpture is reticulate-simplibaculate on pollen of Lennoa and Pholisma, and reticulate-duplibaculate on pollen of Ammobroma. Pollen morphology supports placement of Lennoaceae in the Polemoniales near the Boraginaceae and Hydrophyllaceae.  相似文献   

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泽泻科的花粉形态研究   总被引:5,自引:0,他引:5  
本文对泽泻科11属27种代表植物的花粉进行了光学显微镜、扫描电镜和透射电镜观察。在系统描述了该科及各属植物花粉形态的基础上,将泽泻科植物的花粉划分为3种类型,即少果泽苔草型、慈菇型和泽泻型。根据花粉形态特征的比较,并依据泽泻科植物祖先类群的花粉具有船形、具单沟萌发孔、花粉外壁具明显的刺状纹饰、覆盖层完整无通道等特征,作者认为泽泻科植物花粉形态的如下演化趋势是明显的:由船形演化为卵球形、球形和多面体球形;由单沟萌发孔经过一无孔的中间类型演化为散孔类型;孔膜由光滑演化为具颗粒和小刺;萌发孔不内陷进化到内陷;花粉粒外壁的刺状纹饰逐渐过渡为颗粒状纹饰或者消失,以及覆盖层由无通道到具细通道和通道。  相似文献   

13.
The pollen of three monotypic genera, Circaeaster, Kingdonia, and Sargentodoxa has been examined by light and scanning electron microscopy and in the case of the last genus, also by transmission electron microscopy. The type of tectum found in Circaeaster and Kingdonia, derivations of a compound layer of striae, has a restricted distribution in the Order Ranunculales. Of 64 genera examined in this order only six had species with a similar tectum. They include Achlys, Epimedium, Jeffersonia, and Vancouveria of the Berberidaceae s.l., the controversial Hydrastis, and Trollius of the Ranunculaceae. Circaeaster and Kingdonia have been considered as related since both have rare and primitive vegetative characteristics, the most notable being open dichotomous leaf venation. They are probably best treated as a ditypic family, Circaeasteraceae. The pollen of Sargentodoxa, especially the structure of the exine, closely resembles that of the Lardizabalaceae. However, the fruits of Sargentodoxa have been considered to be distinct from those of the Lardizabalaceae, suggesting that it be treated as a separate, but closely allied, family.  相似文献   

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禾本科针茅族(Stipeae)7种花粉形态比较研究   总被引:2,自引:0,他引:2  
利用光学显微镜(LM)和扫描电子显微镜(SEM)观察了针茅族7种花粉形态.观察显示,花粉形态均为近球形,具远极单孔,并有萌发孔盖(Operculum).LM观察到花粉外壁纹饰具粗细不一的颗粒状结构,SEM则可辨不同种类的颗粒或瘤状结构的大小及其形成图案的差异,其中芨芨草属(Achnatherum)花粉外壁纹饰的种间差异...  相似文献   

16.
The morphology and anatomy of 105 flowers representing 13 species and 6 genera of the Canellaceae are summarized. The flowers are borne in axillary or terminal racemes, cymes, or small groups, or solitary, in an axillary or terminal position. The flowers are characterized as follows: bisexual, hypogynous; sepals 3, thick and leathery; petals, 5–12, free or united into tube at base, rather thick, in 1 or 2 whorls and/or spirals; androecium of 6–12 stamens united by their filaments forming a tube, anthers with longitudinal extrorse dehiscence; gynoecium of 2–6 carpels fused by their ventral margins; 2–6 placentae. There are 2 vascular bundles (rarely 3) to each sepal, 3 to each petal (some of the inner petals have only 1), 1 to each stamen and 1 trace to each carpel. The petal and stamen bundles have a common origin. All the data accumulated in this series on the Canellaceae indicate that the correct systematic placement of the Canellaceae is in the woody Ranales, perhaps in a complex with the Myristicaceae.  相似文献   

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马尾树科及其近缘科花粉形态研究   总被引:1,自引:0,他引:1  
本文观察了马尾树科(Rhoipteleaceae)、胡桃科(Juglandaceae)以及桦木科(Be-tulaceae)、9属9种植物花粉形态。马尾树科与桦木科桦木属(Betula L.)花粉粒均为扁球形,极面观呈钝三角形,萌发孔类型均为多孔类型,孔之间均有弓形加厚,而且外表面均具细颗粒状雕纹。而胡桃科大多为多边形、散孔类型。根据花粉形态资料,探讨了马尾树科的系统位置。  相似文献   

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伯乐树科及其近缘科的花粉形态研究   总被引:5,自引:0,他引:5  
本文观察了伯乐树科、省沽油科、牛栓藤科、七叶树科、无患子科、罂粟科,共6科、17属、21种植物的花粉形态。依据花粉资料,探讨了伯乐树科的系统位置。认为伯乐树科与无患子目中牛栓藤科关系较为密切。牛栓藤科较为进化,伯乐树科较为原始。与无患子目中其他一些科关系不明显。伯乐树科与罂粟科、豆科中云实亚科的花粉形态有某些相似,而伯乐树科较为进化。与辣木科、白花菜科花粉形态较少相似。  相似文献   

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