水盾草科系统位置评述

水盾草科(Cabombaceae)是双子叶植物。水盾草科包括2属: 水盾草属(Cabomba Aublet.)和莼菜属(Brasenia Schreb.)。形态学研究显示水盾草科具有许多原始性状, 而且在其适应水生环境的过程中经历了性状退化。水盾草科又被称为“古草本”。最新的分子系统发育研究显示, 水盾草科是现存被子植物系统树基部ANITA类群的成员之一。但有关水盾草科的系统位置存在争议。被子植物的起源与早期分化一直是植物学家关注的热点。本文对该科系统位置的研究历史与现状进行评述。     

中国北部莼菜(Brasenia schreberi)地史分布与生态适应

本文报道了中国北部新分布的水盾草科(Cabombaceae)植物。过去根据蔬菜属(Brasenia)将水盾草科译为莼菜科是不恰当的,因为水盾草科的命名模式为水盾草属(Cabomba),故建议将Cabombaceae译为水盾草科。 本文概述了水盾草科的系统分类位置,讨论了莼菜的化石与现代分布样式,认为冰期气候是影响其分布的主导因子。同时根据幼苗的形态特征,按重演论观点,推测了莼菜的起源,其祖先可能是毛莨科的古植物。此外,还研究了莼菜花部的昼夜沉浮节律,冬芽的结构和生态适应及胶被的特征和功能等。     

互叶梅科系统位置评述

互叶梅科(Amborellaceae)一属一种。形态学研究显示互叶梅(Amborella,tricopoda Baill．)具有许多原始性状。大多数最新的分子系统发育研究显示,互叶梅科是现存被子植物的最基部类群。但有关互叶梅科的系统位置存在争议。被子植物(有花植物)的起源和辐射一直是植物学家关注的热点。本文将对该科系统位置的研究历史与现状进行评述。     

互叶梅科系统位置评述

互叶梅科 Amborellaceae 一属一种 .形态学研究显示互叶梅 Amborella tricopoda Baill. 具有许多原始性状 .大多数最新的分子系统发育研究显示 ,互叶梅科是现存被子植物的最基部类群 .但有关互叶梅科的系统位置存在争议 .被子植物 有花植物 的起源和辐射一直是植物学家关注的热点 .本文将对该科系统位置的研究历史与现状进行评述     

腺齿木科系统位置评述

腺齿木科(Trimeniaceae)含2属5种。形态学研究显示腺齿木科具有许多原始性状。最新的分子系统发育研究显示,腺齿木科是现存被子植物的重要基部类群之一。但有关腺齿木科的系统位置存在争议。被子植物(有花植物)的起源与辐射一直是植物系统学家关注的热点。对该科系统位置的研究历史与现状进行评述。     

金鱼藻科系统位置评述

金鱼藻科(ceratophyllaceae)含1属7种,广布全世界。形态学研究显示,金鱼藻科具有许多难以解释的性状,与其它类群无法比较;最新的分子系统发育研究显示,金鱼藻科是现存被子植物的基部类群之一;有关金鱼藻科的系统位置存在争议,被子植物(有花植物)的起源与辐射一直是植物系统学家关注的热点。本文对该科系统位置的研究历史与现状进行评述。     

中国粟米草科分类修订

粟米草科(Molluginaceae)隶属于石竹目,是一个分类极为困难的被子植物类群,关于该科的分类学界定在众多不同被子植物分类系统中争议颇大。在最近的分子系统学研究中,粟米草科的范围被准确界定,全球共包含11属。在此基础上对中国粟米草科类群进行了分类修订,最终确认中国产粟米草科植物5属7种,其中线叶漆姑粟草[Hypertelis umbellata (Forssk.)Thulin]为中国分布新记录种。更新了分种检索表,并提供了各属形态描述及相关物种的地理分布图。     

中国大陆水生植物新逸生种——红菊花草

报道了中国大陆水盾草科(莼菜科)水盾草属的新归化水生植物——红菊花草Cabomba furcata Schult. & Schult. f.,凭证标本存于中国科学院华南植物园标本馆(IBSC)。     

睡莲科系统位置评述

形态学研究显示睡莲科Nymphaeaceae具有许多原始性状。睡莲科又被称为“古草本”。最新的分子系统发育研究显示,睡莲科是现存被子植物系统树根部附近最早分异谱系的演化支之一,对研究被子植物(有花植物)的起源与早期进化具有重要价值,但有关睡莲科的范围和系统位置存在争议。被子植物的起源与辐射一直是植物学家关注的热点。本文对该科系统位置的研究历史与现状进行了评述。     

莲科系统位置评述

莲科含1属1种2亚种,以具有最古老的有活力的种子而著称。形态学研究显示,莲不仅具有双子叶植物特征,而且又具有单子叶植物的某些性状。因此,对研究被子植物(有花植物)的起源与演化以及单子叶植物的起源具有重要价值。被子植物(有花植物)的起源与辐射一直是植物学家关注的热点,有关莲科的系统位置存在争议。该文对该科系统位置的研究历史与现状进行评述。     

木兰藤科系统位置评述

木兰藤科(Austrobaileyaceae)含1属2种,是系统学上最孤立的科之一。其花粉类似于最古老的被子植物化石之一:晚白垩世的棒纹粉。最新的分子系统发育研究结果表明,木兰藤科是现存被子植物的基部类群之一,其对于被子植物的起源与早期进化的研究具有重要价值。被子植物(有花植物)的起源和辐射一直是植物学家关注的热点。有关木兰藤科的系统位置一直存在争议。本文对该科系统位置的研究历史与现状进行评述。     

Xylem of early angiosperms: Novel microstructure in stem tracheids of Barclaya (Nymphaeaceae)

Pit membranes of stem tracheids of all recognized species of Barclaya, an Indomalaysian genus of Nymphaeaceae, were studied with scanning electron microscopy (SEM). Pit membranes of the tracheids are composed of two thick layers, both constructed of fibrils much larger than those of tracheary elements of angiosperms other than Nymphaeaceae. The outer (distal) layer, which comprises the continuous primary wall around the tracheids, is spongiform, perforated by porosities of relatively uniform size, and confined to or most prominent on end walls of stem tracheids. The second layer consists of thick widely spaced fibrils that are oriented axially and are laid down proximally (facing the cell lumen) to the first (outer) layer, although continuous with it. These axial fibrils are attached at their ends to the pit cavities. This peculiar microstructure is not known outside Nymphaeaceae except in Brasenia and Cabomba (Cabombaceae, Nymphaeales), and has not been previously described for Barclaya. The longitudinally oriented threads and strands in perforation plates of secondary xylem of wood and stems of a variety of primitive woody angiosperms (e.g., Illicium) are not homologous to the pit membrane structure observed in stem tracheids of Barclaya, which, like other Nymphaeaceae, has only primary xylem and no perforation plates. The tracheid microstructure reported here is different from pit structures observed in any other group of vascular plants, living or fossil. The tracheid stem microstructures of Barclaya and other Nymphaeaceae appear to be a synapomorphy of Nymphaeaceae and Cabombaceae, and need further study with respect to ultrastructure and function.     

Phylogeny and divergence of basal angiosperms inferred from<Emphasis Type="Italic"> APETALA3</Emphasis>- and<Emphasis Type="Italic"> PISTILLATA</Emphasis>-like MADS-box genes

The B-class MADS-box genes composed of APETALA3 (AP3) and PISTILLATA (PI) lineages play an important role in petal and stamen identity in previously studied flowering plants. We investigated the diversification of the AP3-like and PI-like MADS-box genes of eight species in five basal angiosperm families: Amborella trichopoda (Amborellaceae); Brasenia schreberi and Cabomba caroliniana (Cabombaceae); Euryale ferox, Nuphar japonicum, and Nymphaea tetragona (Nymphaeaceae); Illicium anisatum (Illiciaceae); and Kadsura japonica (Schisandraceae). Sequence analysis showed that a four amino acid deletion in the K domain, which was found in all previously reported angiosperm PI genes, exists in a PI homologue of Schisandraceae, but not in six PI homologues of the Amborellaceae, Cabombaceae, and Nymphaeaceae, suggesting that the Amborellaceae, Cabombaceae, and Nymphaeaceae are basalmost lineages in angiosperms. The results of molecular phylogenetic analyses were not inconsistent with this hypothesis. The AP3 and PI homologues from Amborella share a sequence of five amino acids in the 5 region of exon 7. Using the linearized tree and likelihood methods, the divergence time between the AP3 and PI lineages was estimated as somewhere between immediately after to several tens of millions of years after the split between angiosperms and extant gymnosperms. Estimates of the age of the most recent common ancestor of all extant angiosperms range from ~140–210 Ma, depending on the trees used and assumptions made.     

Schmeissneria:An angiosperm from the Early Jurassic

The origin of angiosperms has been a focus of intensive research for a long time.The so-called pre-Cretaceous angiosperms,including Schmeissneria,are usually clouded with doubt.To expel the cloud around the enigmatic Schmeissneria,the syntype and new materials of Schmeissneria collected previously in Germany and recently in China are studied.These materials include female inflorescences and infructescences.The latter are old materials but were under-studied previously.Light microscopy and scanning electron microscope observations indicate that the fruits in these infructescences have in situ seeds enclosed,and that the ovaries are closed be fore pollination.Thus the plants meet two strict criteria for angiosperms:angiospermy plus angio-ovuly.Placing Schmeissneria in angiosperms will extend the record of angiosperms up to the Early Jurassic,more compatible with many molecular dating conclusions on the age of angiosperms,and demanding a reassessment of the current doctrines on the origin of angiosperms.Although the phylogenetic relationship of Schmeissneria to other angiosperms apparently is still an open question,this study adds to research concerning the origin of angiosperms.     

Schmeissneria: An angiosperm from the Early Jurassic

The origin of angiosperms has been a focus of intensive research for a long time. The so-called preCretaceous angiosperms, including Schmeissneria, are usually clouded with doubt. To expel the cloud around the enigmatic Schmeissneria, the syntype and new materials of Schmeissneria collected previously in Germany and recently in China are studied. These materials include female inflorescences and infructescences. The latter are old materials but were under-studied previously. Light microscopy and scanning electron microscope observations indicate that the fruits in these infructescences have in situ seeds enclosed, and that the ovaries are closed before pollination. Thus the plants meet two strict criteria for angiosperms: angiospermy plus angio-ovuly. Placing Schmeissneria in angiosperms will extend the record of angiosperms up to the Early Jurassic, more compatible with many molecular dating conclusions on the age of angiosperms, and demanding a reassessment of the current doctrines on the origin of angiosperms. Although the phylogenetic relationship of Schmeissneria to other angiosperms apparently is still an open question, this study adds to research concerning the origin of angiosperms.