四川被子植物区系特征的初步研究

四川地区被子植物区系188科1493属8711种及1252变种,全球50％以上的科都有代表,与毗邻地区及世界植物区系有着广泛而密切的联系。区系古老而原始,珍稀孑遗类群丰富;单型或少种的科属众多,含100种以上的大科和大属也十分繁荣;含5种以下的属占76.89%,但占总属数约22.64%的多种属和大属是区系的主体,包含区系总种数的63.28%。科的分布类型有明显热带性质,属、种的分布类型反映出典型的亚热带属性。优势现象明显,特有类群和表征类群丰富。该地区被子植物区系对中国乃至东亚都有代表性。     

四川被子植物区系特征的初步研究

四川地区被子植物区系188科1493属8 711种及1 252变种,全球50%以上的科都有代表,与毗邻地区及世界植物区系有着广泛而密切的联系.区系古老而原始,珍稀孑遗类群丰富;单型或少种的科属众多,含100种以上的大科和大属也十分繁茂;含5种以下的属占76.89%,但占总属数约22.64%的多种属和大属是区系的主体,包含区系总种数的63.28%.科的分布类型有明显热带性质,属、种的分布类型反映出典型的亚热带属性.优势现象明显,特有类群和表征类群丰富.该地区被子植物区系对中国乃至东亚都有代表性.     

被子植物的起源-以喜花虻类化石为据

喜花昆虫在被子植物的起源和早期演化上起着决定性的作用。虻类化石中的许多类群都有访花习性,它们为研究被子植物的起源提供了独特材料。虽然最老的被子植物化石还没有发现,但是喜花虻类的爆发式出现,表示了被子植物出现的时间和地点。本文主要以欧亚大陆东部,特别是中国辽西的侏罗杨虻类化石为材料,在功能形态分析和与现代类群作对比的基础上,证证实了虻类是显花植物最原始的传粉类群之一。中国东北、哈萨克斯坦和西伯利来晚     

被子植物起源研究中几种观点的思考

对被子植物起源研究中的几种观点进行了讨论。(1)由于被子植物存在着一组共同的性状,它们不可能是从不同祖先起源的,而是有着共同的祖先。被子植物是一个单源起源的类群。现存被子植物分类系统是依据包括形态学(广义)、分子系统学、古植物学和植物地理学等的综合性状建立的,只能表示出现存类群的亲缘关系并且追溯到它们最近的祖先。人们现在还不可能建立一个包括全部已绝灭的类群和现代生存类群的谱系发生系统。因此,现存被子植物分类系统只能看作是“亲缘”系统。(2)分析了用于推测被子植物起源时间的分子、化石和地理分布证据。我们认为,要确定被子植物起源时间,植物化石是一类重要证据,但化石只能说是植物本身可保存部分和当时当地所提供的化石条件的综合反映,它们不可能就是植物类群或种的起源时间。人们还必须考虑到化石本身的演化历史。应用分子钟也是一种手段,但误差比较大。如果我们除了利用上述两种资料之外,根据植物类群的现代分布格局及其形成,把植物的演化同地球的历史和板块运动联系起来,以推断它们起源的时间,这无疑会增加其可信度。通过对56个种子植物不同演化水平的重要科属地理分布的研究结果,我们曾提出被子植物的起源时间可能要追溯到早侏罗世,甚至晚三叠世。(3)分析了基于分子证据所提出的被子植物基部类群——ANITA成员(包括无油樟科Amborellaceae、睡莲科Nymphaeaceae、八角目Illiciales、早落瓣科Trimeniaceae、木兰藤科Austrobaileyaceae)的性质,讨论了ANITA成员在现代几个被子植物分类系统中的系统位置的不同观点,评价了它们的形态学(广义)性状。指出ANITA的成员由于包含大量的祖征,是属于原始的类群。但由于它们的共有衍征很少,如花粉球形,说明它们在被子植物演化早期就分道扬镳了,沿着不同的传代线分化。因此ANITA是一个源于不同传代线的复合群。     

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。     

吉林省延吉盆地早白垩世被子植物化石

吉林省延吉盆地大拉子组的被子植物化石约有10种。它们具有早白垩世较原始被子植物的形态特征,和北美早白垩世波托马克群的Ⅰ-Ⅱ带的植物分子相同,并与蒙古早白垩世(Neocomian)植物群有些接近,而与苏联、葡萄牙等地的早白垩世(Albian)的被子植物差别甚大,故大拉子组的时代可暂归于 Aptian。植物组合特征说明在早白垩世中期,北半球的欧亚和北美植物区系具有更为密切的关系。并从植物组合及沉积特征分析了古环境。     

中国台湾海峡两岸原始被子植物的起源、分化和关系

文章分析了中国台湾海峡两岸共有20个原始被子植物科的地理分布,区系分化,起源以及它们之间的关系,进一步证明台湾海峡两海的植物区系是一个统一的区系,台湾省是一个东亚植物区系的马来西亚植物区系交汇,而以东亚植物区系成分占优势的地区,台淡丰富的原始被子植物特有种,大多种是在台湾同大陆分离以后形成的,带有新特有的种的性质,中国大陆同台湾现存的原始被子植物科属在区系上是共同起源的,起源的时间和地区可以追溯到中生代的华夏古陆,即在白垩纪末台湾同大陆第一次分裂之前就已经表成了,第四纪冰期大陆同台湾之间的陆桥,对两岸原始被子植物的分布几乎没有影响。     

四川裸子植物区系研究

四川裸子植物 9科 2 8属 1 0 1种 (含变种 ) ,区系成分为亚热带类型。东部地区古地理环境温和稳定 ,至今保存着许多珍稀孑遗的类群 ;西部地区古地理环境变化频繁 ,科、属少而种类丰富。东、西部差异明显。松柏类在这一地区十分突出 ,集中了从原始到进化的几乎各个类群的代表。四川裸子植物区系既不是泛北极区系迁移的产物 ,也不是热带区系的后裔 ,而是在二叠纪以来的地质历史发展过程中本地起源和发展起来的。     

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     

被子植物助细胞中钙含量的变化

助细胞是被子植物受精过程中花粉管进入胚囊并释放精子及其内容物的场所,而助细胞中不同时期的钙含量与受精作用的顺利完成密切相关。在大多数植物中,助细胞是成熟胚囊中钙含量最高的细胞。传粉后在花粉管中所产生的信号诱导下,助细胞中钙含量还可能继续增加。花粉管进入退化助细胞后,在超高钙环境中破裂并释放精子,精子沿退化助细胞转移到受精靶区实现双受精。随后助细胞中的钙含量迅速降低。因此钙在吸引花粉管、雄配子释放甚至雄配子转移等过程中都发挥了重要作用。     

Phylogeny of the Gardenieae (Rubiaceae)

The phylogeny of Gardenieae (Rubiaceae) is evaluated using 70 morphological and anatomical characters and 81 terminal taxa. After successive reweighting of the characters and modified bootstrap tests the following is concluded. The position of the Diplosporinae genera Argocoffeopsis, Calycosiphonia, Cremaspora and Tricalysia with the genera belonging to the tribes Aulacocalyceae, Coffeeae, Octotropideae and Pavetteae, suggests that this subtribe does not belong in Gardenieae. Posoqueria is nested among outgroup genera and consequently is not a member of the tribe. Robbrecht & Puff's informal 'tetrad group' is monophyletic. Likewise, their 'Alibertia group' is supported as monophyletic, although slightly rearranged. On the other hand, their 'Aidia group' must he greatly expanded with several genera in order to be monophyletic, but the monophyly of this group is weakly supported. Several disputed genera should be included in Gardenieae ( Anomanthodia, Amaioua, Brachytome , and supposedly Bertiera ). Most inferred groups, however, exhibit low bootstrap values and should he viewed with caution.     

Two new species and combinations of Stipa L. (Graminae) from northwest Africa

Two new species of Stipa L. S. meridionalis and S. magrebensis, are described from northern Africa, and two new combinations have been made: V. barbata subsp. breripila and S. gigantea subsp. maroccana.     

The origin of unique diversity in deglaciated areas: traces of Pleistocene processes in north‐European endemics from the Galium pusillum polyploid complex (Rubiaceae)

The role of glacial oscillations in shaping plant diversity has been only rarely addressed in endemics of formerly glaciated areas. The Galium pusillum group represents a rare example of an ecologically diverse and ploidy‐variable species complex that exhibits substantial diversity in deglaciated northern Europe. Using AFLP and plastid and nuclear DNA sequences of 67 populations from northern, central, and western Europe with known ecological preferences, we elucidate the evolutionary history of lineages restricted to deglaciated areas and identify the eco‐geographic partitioning of their genetic variation. We reveal three distinct endemic northern lineages: (i) diploids from southern Sweden + the British Isles, (ii) tetraploids from southern Scandinavia and the British Isles that show signs of ancient hybridization between the first lineage and populations from unglaciated central Europe, and (iii) tetraploids from Iceland + central Norway. Available evidence supports a stepwise differentiation of these three lineages that started at least before the last glacial maximum by processes of genome duplication, interlineage hybridization and/or allopatric evolution in distinct periglacial refugia. We reject the hypothesis of more recent postglacial speciation. Ecological characteristics of the populations under study only partly reflect genetic variation and suggest broad niches of postglacial colonizers. Despite their largely allopatric modern distributions, the north‐European lineages of the G. pusillum group do not show signs of rapid postglacial divergence, in contrast to most other northern endemics. Our study suggests that plants inhabiting deglaciated areas outside the Arctic may exhibit very different evolutionary histories compared with their more thoroughly investigated high‐arctic counterparts.     

Two new fossil flowers of magnoliid affinity from the Late Cretaceous of New Jersey

Two taxa of cupulate magnoliid fossil flowers, Cronquistiflora and Detrusandra, are described from the Late Cretaceous (Turonian, ∼90 million years before present [MYBP]) Raritan (or lower Magothy) Formation of New Jersey. The fossil taxa are represented by flowers at various stages of development, associated fragments of cup-shaped floral receptacles with attached anthers, and isolated anthers. Both taxa have laminar stamens with adaxial thecae and valvate dehiscence. Pollen is boat-shaped and foveolate in anthers associated with Cronquistiflora and spherical with reticulate ornamentation in Detrusandra. Cup-shaped receptacles are externally bracteose in both taxa. The receptacle of Cronquistiflora is broader than the campanulate one of Detrusandra. Cronquistiflora also has more carpels (∼50 in a spiral vs. ∼5 in a whorl or tight spiral). In Detrusandra the carpels are surrounded by dorsiventrally flattened structures (pistillodes?) that are remote from the attachment of the stamens near the distal rim of the receptacular cupule. Detrusandra stigmas are rounded and bilobed, while those of Cronquistiflora, although bilateral in symmetry, are somewhat peltate. The fossil taxa share prominent characters with extant cupulate magnoliids (e.g., Eupomatia, Calycanthus), but also share characters with other magnoliids including Winteraceae. These fossils represent taxa that are character mosaics relative to currently recognized families. Inclusion of these fossils in existing data matrices and ensuing phylogenetic analyses effect changes in tree topologies consistent with their mosaicism relative to modern taxa. But such analyses do not definitively demonstrate the affinities of the fossils other than illustrating that these fossils are generalized magnoliids. Additional analysis of modern and fossil magnoliids is necessary to fully appreciate the phylogenetic significance and positions of these fossil taxa. However, the results of the phylogenetic analyses do introduce the possibility that extinct taxa of Magnoliales with cupulate floral receptacles were transitional between basal angiosperms and those with tricolpate pollen. The fossils provide insights into the timing of evolution of character complexes now associated with coleopteran pollination.     

被子植物生殖细胞和精细胞

随着被子植物精细胞分离技术的突破和细胞生物学以及分子生物学技术的发展,对被子植物精细胞的研究不断深入。在以前细胞生物学研究的基础上结合近年来的分子生物学研究结果对被子植物雄性生殖细胞的产生、精细胞的形成和发育以及有关精细胞的表面蛋白质、精细胞的特异启动子、精细胞cDNA文库的构建等分子生物学研究进展和今后的发展趋势进行了综述。