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1.
应用扫描电镜地国产水鳖科6属植物的果皮微形态特征进行了初步的观察。结果表明水鳖科各属植物在果皮面纹饰及表皮细胞形态,径向壁和横向凸出与否等特征上存在差异,可以作为属间分类的依据之一.从果皮微形态特征来看,水鳖属和海菜花属差异很大,支持将它们分别作为不同的族处理的观点,而水筛属和苦草属则较为近缘。果皮微形态下的观察结果表明水鳖科和泽泻科植物在果皮表现细胞形态,径向壁明显凸出等方面十分相似,因而支持了  相似文献   

2.
水鳖科9属15种植物花粉形态的研究   总被引:5,自引:0,他引:5  
应用光学显微镜、扫描电镜和透射电镜对水鳖科Hydrocharitaceae 9属15种植物的花粉形态进行了观察。水鳖科植物花粉为圆球形至近椭球形,无萌发孔或偶为单沟萌发孔,外壁纹饰通常为小刺状纹饰,刺密集或稀疏,花粉表面具瘤状、疣状、颗粒状、皱波状突起或光滑。外壁由覆盖层、柱状层和基层组成。覆盖层厚或较薄,柱状层小柱发育不明显,基层薄。水鳖科植物在花粉大小、纹饰类型、刺的长短、密度、形态、萌发孔的有无以及花粉壁的结构等方面表现出了较为明显的差异,这些特征对探讨类群间关系具有较重要意义。由于黑藻属Hydrilla和Stratiotes属花粉较为特殊,支持将它们各自作为一个独立的族处理。水鳖科植物花粉外壁纹饰和结构特点表明该科与水雍科Aponogetonaceae、泽泻科Alismataceae和花蔺科Butomaceae等近缘,而该科植物花粉大多无萌发孔等则反应了该科与茨藻目Najadales植物有密切联系。  相似文献   

3.
由于四福花Tetradoxa顶花、侧花均为典型的4数花,并被认为是科内最原始的属,因而长期以来关于五福花Adoxa“总苞一萼”还是“萼一花冠”的争议得到了彻底解决。根据本研究,五福花顶花和侧花的变异痃较五福花科另外3个分类群要高得多。五福花顶花和侧花的变异率分别为20%和361%。通过后位雄蕊的退化和两则相邻花瓣的融合,雄蕊和花瓣从6数至3数的减少系列仅存在于五福花中。本文假设五福花科顶花和侧花的  相似文献   

4.
孙坤  陈家宽 《植物学报》1998,15(1):63-67
应用扫描电镜对国产水鳖科6属植物的果皮微形态特征进行了初步的观察。结果表明水鳖科各属植物在果皮表面纹饰及表皮细胞形态,径向壁和横向壁凸出与否等特征上存在差异,可以作为属间分类的依据之一。从果皮微形态特征来看,水鳖属和海菜花属差异很大,支持将它们分别作为不同的族处理的观点,而水筛属和苦草属则较为近缘。果皮微形态下的观察结果表明水鳖科和泽泻科植物在果皮表面细胞形态,径向壁明显凸出等方面十分相似,因而支持了水鳖科与泽泻目近缘的观点。  相似文献   

5.
中国水鳖科( Hydrocharitaceae )植物的果皮微形态特征   总被引:1,自引:0,他引:1  
应用扫描电镜对国产水鳖科6属植物的果皮微形态特征进行了初步的观察。结果表明水鳖科各属植物在果皮表面纹饰及表皮细胞形态,径向壁和横向壁凸出与否等特征上存在差异,可以作为属间分类的依据之一。从果皮微形态特征来看,水鳖属和海菜花属差异很大,支持将它们分别作为不同的族处理的观点,而水筛属和苦草属则较为近缘。果皮微形态下的观察结果表明水鳖科和泽泻科植物在果皮表面细胞形态,径向壁明显凸出等方面十分相似,因而支持了水鳖科与泽泻目近缘的观点。  相似文献   

6.
7.
中国水鳖科植物种皮微形态特征及其系统学意义   总被引:5,自引:1,他引:5  
通过扫描电镜对国产水鳖科植物(包括6属13种)的种皮微形态特征进行观察,并作了系统描述。根据种皮细胞形态、外种皮表面纹饰和内种皮内层小瘤状突起的特点将水鳖科植物的种皮微形态特征划分为3种类型,即海菜花型(海菜花属)、水鳖型(水鳖属)和苦草型(苦草属、水筛属、虾子草属和黑藻属),并作出了分属检索表。本文结果表明,种皮微形态特征可作为该科族、属以及属内种级水平分类的依据,对探讨属间关系和该科的系统发育关系亦具有重要的价值。种皮微形态特征支持Hutchinson(1959)和Eckhardt(1964)将海菜花属和水鳖属分别作为一个独立的族处理的观点。苦草属、水筛属和虾子草属种皮微形态特征的高度相似性表明它们间有密切的联系,不支持将它们置于不同亚科和族的分类处理。黑藻属虽与上述3属近缘,但其外种皮特征则较为独特,因此与水筛属放在不同族中更为合理。本文种皮微形态特征的研究结果支持iki1937)和Shaffer-Fehre(1991b)等关于水鳖科与茨藻科近缘的观点。  相似文献   

8.
本文利用光镜及扫描电镜对湖北省泽泻科、水鳖科、眼子菜科及茨藻科11属29种1变种1变型植物(另加采于湛江的软骨草)的花粉形态进行了研究,发现泽泻科植物花粉具多个圆形萌发孔,外壁表面为小刺状纹饰;茨藻科植物花粉具远极单槽,表面为绉波状纹饰;眼子菜科及本文研究的水鳖科植物花粉均无萌发孔,分别具网状和小刺状饰纹饰。1.茨藻科植物花粉最原始,泽泻科花粉较进化,眼子菜科花粉较水鳖科花粉进化;2.泽泻属与泽苔草属花粉较慈姑属花粉原始;3.鞘叶眼子菜亚屈花粉较眼子菜亚属的花粉处于更高演化阶段;4.多孔茨藻花粉在该科中最原始。本文工作尚对易变形水生植物花粉形态研究方法进行了尝试。  相似文献   

9.
对狗牙根(Cynodon dactylon‘C299’)花序发育过程中的形态学变化进行了观察。结果表明,‘C299’花序的整个发育过程可分为8个阶段,即营养生长期、穗轴发生期、苞叶原基分化期、小穗原基分化期、小穗分化期、小花分化期、颖片和内外稃发育期及花药和柱头形成期。其中,穗轴发生期(直立茎上有6~9片叶)是抑制花序形成和决定种子产量的关键时期。  相似文献   

10.
通过野外观察和石蜡切片技术研究了毛竹(Phyllostachys edulis)的花序发育进程。研究结果表明:毛竹的花序为续次发生的假花序,以小穗为单元,4~13个不等,偏向一侧排列(似扫帚状)的小穗组成长约8.01 cm的复穗状花序;当花序伸长至4~5 cm时,形成侧芽结构,小穗原基开始发育,形成各级小穗,直至顶生小穗、侧生小穗出现;当花序伸长至8~10 cm时,颖花原基形成并开始发育,最终形成3个雄蕊和1个雌蕊构成的小花。花序形成初期(5月中旬至6月),苞片紧裹主轴,顶端具缩小叶;随着分蘖小穗的生长和小花开放,植株叶片变黄,整个花序变为褐色,进入种实发育成熟阶段。本文首次报道了毛竹花序的发育进程,进一步丰富了竹类生殖生物学的研究内容,为竹亚科及禾本科的生殖生物学研究积累了丰富的材料。  相似文献   

11.
    
Pseudotaxus pollen cones are compound inflorescences. Wild type and anomalous shaped pollen cones were studied. It is suggested that each perisporangiate microsporangiophore represents a strongly reduced flower (lateral pollen cone) and not a peltate microsporophyll. This explains their position in the axil of a scaly pherophyll. In the wild type, the axis of the flowers is so strongly reduced that it is no longer visible and the primordia of all inserted hyposporangiate microsporangiophores get in contact and fuse to a radial synangium. In some cases, the perisporangiate microsporangiophores/flowers were reduced to a single hyposporangiate microsporangiophore. This shows that the perisporangiate microsporangiophores of Pseudotaxus are not sporophylls, but strongly reduced lateral flowers, each consisting of several lateral hyposporangiate microsporangiophores, which fuse to a radial unit. By a reduction of all pherophylls in the Pseudotaxus inflorescence, the flower-like Taxus pollen cone structure is formed, which however represents an inflorescences with flowers reduced to perisporangiate microsporangiophores. If in Taxus pollen cones the lateral flowers get reduced to a single hyposporangiate microsporangiophore, the Torreya pollen cone is formed. In this case, the lateral hyposporangiate microsporangiophores of Torreya correspond to strongly reduced flowers and not to dorsiventral sporophylls.  相似文献   

12.
    
The pollen cone structure and vasculature of Taxus baccata and T. wallichiana were investigated in the context of comparative studies in other conifers. The results indicate that the simple, flower-like pollen cone of Taxus could be derived from an ancestral compound inflorescence as in Cephalotaxus and Pseudotaxus. In Cephalotaxus, each lateral flower-like structure represents an entire pollen cone, compared with a single perisporangiate microsporangiophore in Pseudotaxus. The microsporangiophores are exclusively perisporangiate in both Pseudotaxus and Taxus, but in Pseudotaxus they are inserted in the axil of a pherophyll. By a simple reduction of these pherophylls, the Taxus pollen cone is formed—a strongly reduced inflorescence with flowers reduced to perisporangiate microsporangiophores, which are inserted directly at the cone axis, without pherophylls. Thus, the perisporangiate Taxus microsporangiophores correspond to the axillary flowers in Cephalotaxus and Pseudotaxus. The Taxus flower results from a strong reduction of an ancestral Cephalotaxus-like flower type (lateral pollen cones), where all remaining hyposporangiate microsporangiophores have fused to a radial structure during evolution. Thus, perisporangiate Taxus microsporangiophores represent radial synangia and not peltate microsporophylls, suggesting that hyposporangiate microsporangiophores are the ancestral condition in Taxaceae s.l.  相似文献   

13.
    
The oilseed palm genus Acrocomia is suitable for sustainable oil production in South America. The high phenotypic diversity of wild populations poses a challenge for the delimitation of the genus. Comparing the inflorescence architecture, a first-order panicle, and staminate and pistillate flower traits could be a valuable tool in resolving the taxonomic disarray. Thus, this study aims to characterize the differences in the inflorescence architecture and floral structures of three common and economically significant Acrocomia species: A. aculeata, A. totai, and A. intumescens. Biometric traits of the inflorescence architecture and floral structures of various Acrocomia accessions in an ex situ germplasm collection in Brazil were assessed. The unweighted pair group method with arithmetic mean (UPGMA) cluster analysis based on the Gower distance was used to measure dissimilarities between the individual plants of the accessions. To our best knowledge, this study provides the first evidence of the presence of second-order rachillae in the genus Acrocomia. Evaluated traits showed a high level of variation within and between accessions, emphasizing the phenotypic diversity of the genus. The accessions of A. totai were distinguishable from those of the other two species by their inflorescence architecture and flower traits. The dissimilarities between A. aculeata and A. intumescens were not sufficient to differentiate both. In conclusion, the quantitative assessment of inflorescence and floral traits is a valuable tool for taxonomic resolution of the genus.  相似文献   

14.
    
The Juniperus Section Caryocedrus (Cupressaceae) is one of the three putatively monophyletic sections of the genus. It is monotypic, presented only by J. drupacea. Male reproductive units of this species show several distinct features distinguishing it distinctly from all other Juniperus species, including an inflorescence‐like arrangement of pollen cones, an increased number of microsporangia per microsporangiophore, and microsporangia attached to the stalk in up to three subsequent rows. The male reproductive units in J. drupacea have been investigated with paraffin technique and SEM. They are hypothesized to represent a distal cluster of densely arranged, simple pollen cones, which are interpreted as being derived from an ancestral condition that is still presented in species of the Section Juniperus. This is assumed to have occurred by a profound reduction of internodes of the fertile shoot axis carrying the pollen cone and a distal shift. The increased number of microsporangia per microsporangiophore may be a response to the decreasing number of pollen cones per tree compensating for the loss of pollen, that occurred during the evolution of inflorescence‐like male reproductive units.  相似文献   

15.
Effect of size of inflorescences, flowers and cones on maximum rate of heat production is analysed allometrically in 23 species of thermogenic plants having diverse structures and ranging between 1.8 and 600 g. Total respiration rate (, µmol s?1) varies with spadix mass (M, g) according to in 15 species of Araceae. Thermal conductance (C, mW °C?1) for spadices scales according to C = 18.5M0.73. Mass does not significantly affect the difference between floral and air temperature. Aroids with exposed appendices with high surface area have high thermal conductance, consistent with the need to vaporize attractive scents. True flowers have significantly lower heat production and thermal conductance, because closed petals retain heat that benefits resident insects. The florets on aroid spadices, either within a floral chamber or spathe, have intermediate thermal conductance, consistent with mixed roles. Mass‐specific rates of respiration are variable between species, but reach 900 nmol s?1 g?1 in aroid male florets, exceeding rates of all other plants and even most animals. Maximum mass‐specific respiration appears to be limited by oxygen delivery through individual cells. Reducing mass‐specific respiration may be one selective influence on the evolution of large size of thermogenic flowers.  相似文献   

16.
中国水仙花芽分化观察及储藏条件对花芽数的影响研究   总被引:2,自引:1,他引:2  
以三年生中国水仙‘金盏银台’为材料,采用石蜡切片法观察其花芽形态分化过程。结果表明:中国水仙的花芽分化从7月上旬开始,到9月中旬形成雌蕊结束。其过程可分为叶芽时期、花序原基形成期、佛焰状总苞形成期、花原基形成期、花冠形成期、雄蕊形成期、雌蕊形成期7个时期。其中花冠形成期较长,20 d左右。花芽的外部形态变化上,分化后期芽的生长速度明显快于前期。对鳞茎球内花序数量的统计结果显示,高温储藏及烟熏法共同使用对中国水仙花序的形成具有很好的促进作用。  相似文献   

17.
庙台械的花序为有限花序,由一顶花和6—9枝侧花枝组成,属圆锥状聚伞花序。一个花序共有14—29朵花,包括两性花、雄花和无性花三类花。根据花在花序上着生的位置,可分为三级。7月初,花序原基形成,在花序轴伸长的同时,侧面形成侧花枝轴原基。花序的顶花最早进行个体发育,随后是侧花枝顶花;侧花枝上同一级花的发育顺序则是从花序的下面向上进行。花器官发生时,花萼原基最先形成,然后是花瓣、雄蕊、心皮和胚珠。  相似文献   

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