4种北极被子植物叶片显微结构和超微结构研究

以采自北极的4种被子植物(高山发草Deschampsia alpina、无茎蝇子草Silene acaulis、仙女木Dryasocto-petala,极柳Salix polaris)为材料,利用光学显微镜和透射电子显微镜,研究了它们叶片显微结构和超微结构.结果显示;(1)高山发草和无茎蝇子草的叶片为等面叶,仙女木和极柳为两面叶,无茎蝇子草和极柳叶肉中含有异细胞;(2)4种植物的细胞超微结构均具有叶绿体紧贴细胞壁分布、叶绿体基质中含有淀粉粒、线粒体紧密地围绕在叶绿体周围的特征,而且高山发草和无茎蝇子草的类囊体出现膨胀,无茎蝇子草和仙女木的细胞基质有大量囊泡,极柳叶绿体内膜附近存在周质网.研究表明,北极植物叶片的结构特点与南极植物和高山植物具有一定的相似之处,北极植物叶片的显微结构和超微结构特征更有利于其适应北极的极端环境.     

Angiosperm diversification through time

The extraordinary diversity of angiosperms is the ultimate outcome of the interplay of speciation and extinction, which determine the net diversification of different lineages. We document the temporal trends of angiosperm diversification rates during their early history. Absolute diversification rates were estimated for order-level clades using ages derived from relaxed molecular clock analyses that included or excluded a maximal constraint to angiosperm age. Diversification rates for angiosperms as a whole ranged from 0.0781 to 0.0909 net speciation events per million years, with dates from the constrained analysis. Diversification through time plots show an inverse relationship between clade age and rate, where the younger clades tend to have the highest rates. Angiosperm diversity is found to have mixed origins: slightly less than half of the living species belong to lineages with low to moderate diversification rates, which appeared between 130 and 102 Mya (Barremian-uppermost Albian; Lower Cretaceous). Slightly over half of the living species belong to lineages with moderate to high diversification rates, which appeared between 102 and 77 Mya (Cenomanian-mid Campanian; Upper Cretaceous). Terminal lineages leading to living angiosperm species, however, may have originated soon or long after the phylogenetic differentiation of the clade to which they belong.     

Angiosperm mitochondrial genomes and mutations

Flowering plants harbor the largest mitochondrial genomes reported so far. At present, the nucleotide sequences of 15 mitochondrial genomes from seven angiosperm species are available, making detailed comparative analysis feasible. The gene content is variable among the species, but the most striking feature is the fluidity of intergenic regions, where species-specific sequences predominate. Additionally, angiosperm mitochondrial genomes, even within a species, show a remarkable amount of rearrangement. We also review mitochondrial mutants in angiosperms from a genomic viewpoint, and discuss how they have arisen. The involvement of nuclear genes in mitochondrial genome stability and organization is currently being revealed through the analysis of mutants.     

Cytoplasmic Connexions between Angiosperm Meiocytes

Massive cytoplasmic connexions are formed between the meiocytesin the anthers of several asngiosperm species studied electronmicroscopically. These cytomictic channels are initiated inthe pre-leptotene period, and persist throughout the meioticprophase. They disappear before meiosis II, after which thespores become totally isolated within the callose tetrad wall.The channels are mostly cylindrical, ranging in diameter between0.5 and 1.5µ. They may account for as much as 24 per centof the interface between neighbouring meiocytes. Nuclear material(DNA) may pass through the channels the phenomenon termed ‘cytomixis’by Gates-but seemingly only in consequence of handling. However,the passage of elements of the endoplasmic reticulum and cytoplasmicorganelles probably occurs in vivo, and it is suggested thatthe whole archesporium in a single loculus behaves as a giantcoenocyte, throughout which cyclosis occurs. The role of thecytomictic channels is presumably connected with the movementof materials during the meiotic prophase. The presence of thechannels accounts for the synchroneity of the mother-cell nucleiin the meiotic division, and also for the sensitivity of anthersto injury. Mechanical damage commonly results in complete sterilization,evidently because of the traumatic effect on the whole linked-cellmass. The inter-dependence of the mother cells also explainswhy attempts to culture isolated meiocytes from early stagesin vitro have been unsuccessful.     

东北地区被子植物新资料

东北地区位于中国东北部,地处欧亚大陆东缘,地域辽阔,环境复杂,植被类型多样,是我国北方植物种类较为丰富、植物区系起源演变发展的重要地区。该研究根据野外实地调查及资料分析,报道了东北地区2种新分布植物,分别是野生堇菜(Viola arvensis)、线叶毛膏菜(Drosera anglica)。野生堇菜为东北地区新归化种,分布于哈尔滨市帽儿山,该种在我国台湾地区有分布,原产于非洲北部、亚洲西南部和欧洲;线叶毛膏菜为中国新记录种,分布于东北长白山区。该属在东北地区还有1种,即圆叶茅膏菜(D.rotundifolia)。两者的主要区别:前者叶为线状匙形,花柱3,每个花柱2分裂至中部;后者叶片近圆形,花柱3,每个花柱深裂至基部。凭证标本保存于东北林业大学植物标本室(NEFI)。这些新资料种的发现,对于丰富东北地区植物种类及对本地区植物多样性的研究具有重要意义。     

东北地区被子植物新资料

报道了东北地区1个新分布种臭茶藨子(Ribes graveolens Bge.)和黑龙江省1个新分布种掌叶大黄(Rheum palmatum L.)。凭证标本保存于东北林业大学植物标本室(NEFU)。     

内蒙古被子植物新资料

报道了内蒙古3个新分布记录属:鼠尾草属(Salvia L.)、单蕊草属(Cinna L.)、裂稃茅属(Schizachne Hackel);3个新分布记录种:荫生鼠尾草(Salvia umbratica Hance)、红果龙葵(Solanum villosum Miller)、单蕊草[Cinna latifolia (Trev.) Griseb.];1个新记录亚种: 裂稃茅[Schizachne purpurascens (Torrey) Swallen subsp.callosa (Turcz.) T.Koyama & Kawano];1个黄芪属(豆科)新变型--皇甫川黄芪.     

贵州省被子植物新记录

报道贵州省2个新记录属——假婆婆纳属(Stimpsonia Wright ex A. Gray)和山涧草属(Chikusichloa Koidz.),以及3个新记录种假婆婆纳(Stimpsonia chamaedryoides Wright ex A. Gray)、山涧草(Chikusichloa aquatica Koidz.)和广东西番莲(Passiflora kwangtungensis Merr.)。三种植物均发现于贵州黎平太平山州级自然保护区,凭证标本存放于中国科学院华南植物园标本馆(IBSC)和中国科学院植物研究所标本馆(PE)。文中描述3种植物的主要特征,并讨论了新发现的广东西番莲叶片变异情况。     

福建省被子植物分布新记录

在闽东地区的植被调查中,发现福建省被子植物地理分布新记录属1个:虉草属(Phalaris Linn.);新记录种4个,分别是虉草(Phalaris arundinacea Linn.)、浙江虎耳草(Saxifraga zhejiangensis Z. Wei. et Y. B. Chang)、莼菜(Brasenia schreberi J. P. Gmel.)和斑地锦(Euphorbia maculate Linn.)。标本存放于宁德师范学院植物标本室(NDTC)。     

Angiosperm classification and phylogeny: a criticism

This is a criticism of Dahlgren's recent classification of angiosperms (1980) and his basic diagram of angiosperm phylogeny. The first is shown to include unnatural orders and super-orders; the second is accordingly as questionable. Basic factors for phylogenetic taxonomy in the angiosperms are considered. Leptocauly leads to parallel evolution and specific multiplication. Nomenclatural artifices for taxonomic equivalence are exposed; the name 'pseudon' is suggested for a conjectural taxon.     

福建被子植物分布新记录Ⅰ

在福建省药用植物资源调查中,陆续发现了福建省被子植物地理新分布记录属及种多个,经整理鉴定,本文报道新分布记录属：八宝属（Hylotelephium）、假奓包叶属（Discocleidion）;新分布记录种：浙江蜡梅（Chimonanthus zhejiangensis）、柳叶蜡梅（Chimonanthus salicifolius）、紫花八宝（Hylotelephium mingjinianum）、冷饭藤（Kadsura oblongifolia）、假奓包叶（Discocleidion rufescens）。凭证标本暂存于福建中医药大学药用植物标本室。     

Angiosperm speciation cools down in the tropics

Recent evidence has questioned whether the Latitudinal Diversity Gradient (LDG), whereby species richness increases towards the Equator, results in higher rates of speciation in the tropics. Allowing for time heterogeneity in speciation rate estimates for over 60,000 angiosperm species, we found that the LDG does not arise from variation in speciation rates because lineages do not speciate faster in the tropics. These results were consistently retrieved using two other methods to test the association between occupancy of tropical habitats and speciation rates. Our speciation rate estimates were robust to the effects of both undescribed species and missing taxa. Overall, our results show that speciation rates follow an opposite pattern to global variation in species richness. Greater ecological opportunity in the temperate zones, stemming from less saturated communities, higher species turnover or greater environmental change, may ultimately explain these results.     

Angiosperm phylogeny based on matK sequence information

Plastid matK gene sequences for 374 genera representing all angiosperm orders and 12 genera of gymnosperms were analyzed using parsimony (MP) and Bayesian inference (BI) approaches. Traditionally, slowly evolving genomic regions have been preferred for deep-level phylogenetic inference in angiosperms. The matK gene evolves approximately three times faster than the widely used plastid genes rbcL and atpB. The MP and BI trees are highly congruent. The robustness of the strict consensus tree supercedes all individual gene analyses and is comparable only to multigene-based phylogenies. Of the 385 nodes resolved, 79% are supported by high jackknife values, averaging 88%. Amborella is sister to the remaining angiosperms, followed by a grade of Nymphaeaceae and Austrobaileyales. Bayesian inference resolves Amborella + Nymphaeaceae as sister to the rest, but with weak (0.42) posterior probability. The MP analysis shows a trichotomy sister to the Austrobaileyales representing eumagnoliids, monocots + Chloranthales, and Ceratophyllum + eudicots. The matK gene produces the highest internal support yet for basal eudicots and, within core eudicots, resolves a crown group comprising Berberidopsidaceae/Aextoxicaceae, Santalales, and Caryophyllales + asterids. Moreover, matK sequences provide good resolution within many angiosperm orders. Combined analyses of matK and other rapidly evolving DNA regions with available multigene data sets have strong potential to enhance resolution and internal support in deep level angiosperm phylogenetics and provide additional insights into angiosperm evolution.     

西藏被子植物新记录

报道了西藏被子植物3种新记录,即石竹科(Caryophyllaceae)的坚硬女娄菜(Silene firma Sieb.et Zucc.)、川续断科(Dipsacaceae)的绿花刺参(Morina chlorantha Diels)和菊科(Asteraceae)的粘毛香青[Anaphalis bulley-ana(J.F.Jeffr.)Chang].     

宁夏被子植物分布新资料

报道了宁夏植物分布的3个新记录种--黑三棱、骆驼刺、婆婆针和1个新记录亚种--柳穿鱼.     

The cuticles of some Angiosperm leaves and fruits

The cuticles of twenty-four species from a wide range of mono- and di-cotyledonous plants were examined by chemical methods. The cuticles differ markedly in the amount and composition of the surface wax, in the thickness of the cuticular membrane, and in the content and composition of the cutin of the membrane. Fruits usually have heavier wax deposits and much thicker membranes than leaves. No direct relationship exists between surface waxiness and thickness of the membrane. Alkanes and primary alcohols are prominent in many of the surface waxes; triterpenoids occur less frequently. The cutin content of the membrane varies considerably; a delicate membrane tends to have a low content of cutin in which fatty acids are prevalent, and a well-developed membrane a higher content of cutin more rich in hydroxy-fatty acids. 10,16-Dihydroxyhexadecanoic acid is often an important constituent of cutin; 9,10,18-trihydroxyoctadecanoic acid is most prominent in the cutin of thicker membranes. The possible influence of the variations in cutin acids upon the structure of cutin and the taxonomic implications of wax and cutin composition are discussed.