乐昌含笑

<正>乐昌含笑(Michelia chapensis Dandy)为木兰科(Magnoliaceae)含笑属植物。乔木,高15～30 m。叶薄革质,倒卵形、狭倒卵形或长圆状倒卵形,长6.5～16 cm,宽3.5～7 cm,先端骤狭短渐尖,基部楔形或阔楔形,上面深绿色,有光泽,侧脉每边9～12条,网脉稀疏;叶柄长1.5～2.5 cm,无托叶痕,嫩时被微柔毛,后脱落无毛。花梗长4～10 mm,被平伏灰色微柔毛,具2～5     

乐昌含笑(木兰科)的核型研究(英文)

首次报道了乐昌含笑(Michelia chapensis)的染色体数目和核型。核型公式为2n=38=28m+6sm+4st(2SAT)。与前人认为整个含笑属都为单一的2A型不同,乐昌含笑的核型属于Stebbins的2B型,具有2对近端着丝粒染色体。而且发现在第9对染色体上有小随体的存在。这些表明在含笑属内含有不同的核型。乐昌含笑在细胞学意义上可能是属内比较进化的类群。对染色体结构的细微改变在木兰科植物的种属进化上的作用进行了简要讨论。     

乐昌含笑不同家系的叶形态与生长差异分析

为了解乐昌含笑(Michelia chapensis)叶形态和生长性状的家系变异特征,对15个家系的叶形态性状和生长指标及其相关性进行了分析.结果表明,乐昌含笑叶片形态在家系间和家系内均存在显著差异,不同家系间以帽子峰家系叶形态的平均变异系数最大(23.55％),乐九5家系的最小(12.63％);不同叶形态性状间以干物...     

东莞凤岗镇臀果木-黄桐风水林群落特征分析

基于样方调查,对东莞凤岗镇臀果木(Pygeum topengii)-黄桐(Endospermum chinense)风水林群落特征进行分析.结果表明,该群落属于南亚热带低地常绿阔叶林的代表性恢复类群.在2 000 m2的样地中,共有维管束植物64种,隶属于39科56属,区系成分以热带亚热带成分为主,占总属数的94%.群落的主要优势树种为臀果木、黄桐、银柴、浙江润楠和小盘木.群落外貌常绿,季相较为明显,生活型以高位芽植物占优势,达67.19%.群落的垂直层次结构分化明显,可划分为乔木层、灌木层、草本层以及由藤本植物和附生植物构成的层片结构.Shannon多样性指数在各层次表现出乔木层>灌木层>藤本植物>草本层的格局,整个群落的Margalef丰富度指数为6.8354,Shannon多样性指数为3.8874,Pielou均匀度指数为0.6479.通过对10个优势树种种群的年龄结构、空间分布格局以及种问协变分析,表明臀果木-黄桐群落处于进展演替阶段,优势种群分布呈现由集群向随机的扩散趋势,并朝着优势种群种间相关关系减弱的方向进行.     

海南霸王岭青梅林群落特征研究

基于海南岛霸王岭林区青梅林群落的野外调查数据,分析了青梅林群落的结构、物种组成以及群落特征.结果表明:(1)青梅林群落中物种数较多的科有茜草科(Rubiaceae),大戟科(Euphorbiaceae)、番荔枝科(Annonaceae),分别有物种13、8、5种;而重要值最大的科为龙脑香科(Dipterocarpaceae).(2)霸王岭青梅林在生活型主要表现为常绿中高位芽的物种较多,占总物种的41.49%;叶级谱表现为中型叶较多,占总数的67.02%,全缘叶物种占总数的92.55%,单叶物种占总数的72.40%,群落中革质叶物种数稍多于纸质叶的物种,另外全缘叶占绝对优势,表现了群落的热带性质和常绿性.(3)霸王岭青梅林中青梅的相对密度达66.12%,表明群落为单优青梅林.青梅林下草本植物稀少,主要由青梅和其它树木的幼树幼苗组成,而藤本植物却异常丰富.(4)青梅林群落中大树较少而小树较多,且乔木层树种分布不均匀,表明海南霸王岭青梅林群落处于发育的初级阶段,而且存在着分化和演替的趋势.     

浙江古田山自然保护区野含笑群落特征研究

野含笑为我国省级珍稀濒危植物。通过对野含笑群落的特征进行分析和研究,结果表明。野含笑群落植物种类丰富,科属组成分散,区系成分复杂。从属的地理成分来看,热带分布的属明显多于温带分布的属。群落的生活型以高位芽植物为主,地面芽植物次之。该群落叶的性质以小型叶、单叶、革质、非全缘为主。群落垂直结构复杂,地上成层明显,可分为乔木层、灌木层和草本层,并有一定数量的层间植物。灌木层一乔木层一草本层物种多样性依次递减。野含笑种群的年龄结构属稳定型。     

澳门青洲山翻白叶树群落特征及物种多样性研究

根据样方调查结果,对澳门青洲山翻白叶树(Pterospermum heterophyllum)群落的种类组成、外貌、结构特征与动态及物种多样性进行分析.结果表明:(1)在1 600 m2样地中,有维管束植物47种,隶属于29科44属;对乔木层和灌木层主要物种的重要值以及频度分析结果显示,该群落是以翻白叶树为主的单优种群落,群落种类组成多样性和水平分布不均匀,其外貌终年常绿;对优势种种群的年龄结构分析显示,该种群处于增长状态;(2)整个群落的物种丰富度Margalef指数为13.72,Shannon-Wiener指数为1.15,Simpson指数为0.875,均匀度指数为0.34,该群落的层次格局为:灌木层>藤本层>乔木层>草本层;(3) 与其他5个不同类型地区森林群的物种多样性比较结果显示,澳门翻白叶树群落的物种多样性明显低于其他5个森林群落.     

辽东栎林林隙特征及其对群落更新的影响

通过对黄土高原马栏林区辽东栎(Ouercus liaotungensis)林林隙的定量研究,发现其林隙大小以20～40和40～60 m2的中小林隙居多,林隙的年龄结构以中期和后期数量居多,林隙形成方式以枯立和干基折断占总数的70.31%,林隙形成木多为1～3个,说明该地区辽东栎林隙多为自然干扰形成,林隙边缘木中辽东栎的株数占绝大多数.在林隙中,不同生活史阶段的辽东栎多度对林隙环境因子的响应不同.幼苗多度与林隙面积和边缘木高度间存在极显著相关关系(R2=0.429,P＜0.01),幼树多度与散射光的强度有极显著相关关系(R2=0.286,P＜0.01),而成树多度与林隙环境因子的关系并不明显,但与林隙内幼树的多度有显著的相关关系(R2=0.175,P＜0.05).     

林芝云杉群落特征的研究

析了林芝云杉( Picea likiangensis var. linzhiensis )群落的种类组成、区系特征、群落外貌、垂直结构和水平结构等特性。结果表明：调查样地共有维管植物144种,隶属于53科116属,其中只含1种的属占81.03%。林芝云杉群落的区系组成、植物生活型谱、叶片性质等特征反映了群落的温带性质。群落垂直结构明显,可分为乔木层、灌木层、草本层及层间植物,乔木层郁闭度为0.4~0.8,林芝云杉大多为乔木层的单一优势种,有时与急尖长苞冷杉(Abies georgei var. smithii)、华山松(Pinus armandii)等混生,而群落植物的水平分布不均匀。优势种种群的年龄结构分析表明,该种群处于稳定状态;群落的物种丰富度为32.6364,其Shannon-Wiener指数为3.0926,Simpson指数为0.9366,均匀度指数为0.8942,且均为草本层>灌木层>乔木层。     

澳门青洲山白楸+假苹婆+破布叶群落特征研究

采用样方调查法对澳门青洲山白楸（Mallotus paniculatus）＋假苹婆（Sterculia lanceolata）＋破布叶（Microcos paniculata）群落的种类组成、外貌、结构特征、区系和物种多样性进行了分析,结果表明,1700m2样方中有维管植物70种,隶属于42科65属,其中热带性分布属占90.32%,群落属于南亚热带常绿阔叶林植被类型。群落外貌常绿,生活型以藤本高位芽为主（占22.86%）。群落的物种丰富度Magarlef指数为8.78,Shannon-Wienner指数为2.22,Simpson指数为0.98,均匀度Pielou指数为0.52。群落各层次的丰富度、Simpson指数以及Shannon-Wienner指数均表现为下木层〉乔木层〉藤本植物〉草本层,均匀度表现为藤本植物〉乔木层〉下木层〉草本层,表明下木层中组成的种类较乔木层多,优势树种较乔木层明显。     

越南植物Michelia tonkinensis(木兰科)的模式考订

Michelia tonkinensis A. Chev.这个名称在发表时未指定模式,曾被处理为M. balansae (Aug. DC.) Dandy的异名。在查阅了其原白和原始材料后,确认采自越南北部Tuyen Quang省的标本——Fleury 37.667 (P)是该种唯一的原始材料,应该作为模式看待,同时确认Michelia tonkinensis是一独立的种,不应该处理为M. balansae的异名。此外,还提供了M. tonkinensis的异名、俗名、描述、分布及查阅的标本等综合信息。     

Abnormalities in sexual development and pollinator limitation in Michelia coriacea (Magnoliaceae), a critically endangered endemic to Southeast Yunnan,China

Michelia coriacea (Magnoliacae) is a critically endangered tree, endemic to Southeast Yunnan province, China. Most of the individuals in the extant populations normally bear flowers, but fruit set and fertile seed production rates were only 6.7% and 0.2%, respectively. To identify possible causes of reproductive barriers, the following studies were carried out: examination of stamen and pistil development; experiments using controlled pollination; observations of behavior and frequency of floral visitors in both cultivated and natural populations. The results revealed that about 60% of pollen was abnormal and approx. 70% of ovules had delayed development. Hand pollination could effectively enhance the fruit set (F_4,25=35.139, P<0.0001) and seed set per fruit (F_4,25=85.022, P<0.0001). Both cultivated and wild M. coriacea had an extremely low frequency of floral visitors. Some beetles, a few species of Andrenidae and some Bombus sp. are likely to be the effective pollinators. The fruit set and seed set per fruit from controlled self-pollination and cross-pollination were significantly different (P<0.05), and thus it is inferred, that inbreeding depression may be a contributing factor in the very low seed production. It appears that low seed set in M. coriacea is due to a combination of factors: abnormalities in pollen and ovules, low number of effective pollinators, and inbreeding depression.     

Phylogenetic reassessment of Hyaloscyphaceae sensu lato (Helotiales, Leotiomycetes) based on multigene analyses

Hyaloscyphaceae is the largest family in Helotiales, Leotiomycetes. It is mainly characterized by minute apothecia with well-differentiated hairs, but its taxonomic delimitation and infrafamilial classification remain ambiguous. This study performed molecular phylogenetic analyses using multiple genes including the ITS-5.8S rDNA, the D1–D2 region of large subunit of rDNA, RNA polymerase II subunit 2, and the mitochondrial small subunit. The primary objective was to evaluate the phylogenetic utility of morphological characters traditionally used in the taxonomy of Hyaloscyphaceae through reassessment of the monophyly of this family and its genera. The phylogenetic analyses inferred Hyaloscyphaceae as being a heterogeneous assemblage of a diverse group of fungi and not supported as monophyletic. Among the three tribes of Hyaloscyphaceae only Lachneae formed a monophyletic lineage. The presence of hairs is rejected as a synapomorphy, since morphologically diversified hairs have originated independently during the evolution of Helotiales. The true- and false-subiculum in Arachnopezizeae are hypothesized to have evolved through different evolutionary processes; the true-subiculum is likely the product of a single evolutionary origin, while the false-subiculum is hypothesized to have originated multiple times. Since Hyaloscyphaceae sensu lato was not resolved as monophyletic, Hyaloscyphaceae sensu stricto is redefined and only applied to the genus Hyaloscypha.     

Structure and development of the style base in Abildgaardia, Bulbostylis, and Fimbristylis (Cyperaceae,Cyperoideae, Abildgaardieae)

The Abildgaardieae tribe within the family Cyperaceae comprises six or seven genera, among which Abildgaardia, Bulbostylis and Fimbristylis pose a challenge regarding their morphological delimitation. Molecular phylogenetic analyses including species of Abildgaardieae are rare, but in most of those studies, Abildgaardia and Fimbristylis appear as more closely related to each other than to the Bulbostylis genus. Duration of the style base has been one of the most widely used characters for delimiting these three genera. The style base is a persistent structure in most species of Bulbostylis and deciduous in Abildgaardia and Fimbristylis. The reasons why the style base may persist or fall off have been scarcely discussed. The assumption that abscission layers are present in the style base of all three genera and the fact that tracheids have been observed in the style base of Bulbostylis suggest that this structure might have histological complexity. In view of this, a complete ontogenetic and anatomical study of the gynoecium has been carried out for all these three genera. It turned out that the style base is histologically simple in Abildgaardia, Bulbostylis and Fimbristylis and shows similar structure and development in all three genera. The fact that the style base has a shorter duration in Abildgaardia and Fimbristylis than in Bulbostylis might be related to the lower number of sclerotised cells that make up such structures in the mature fruit of the former two genera. Abscission of the style and style base may be the result of much simpler reasons than the differentiation of an abscission layer, resulting merely from mechanical shear force effects. Differences among genera have been observed in the shape of the style base and the development of the style. The histological simplicity of the style base is consistent with the homoplastic appearance of this structure in genera that are not closely related (e.g. Rhynchospora). Because of this, while the presence of the thickened style base seems to be a synapomorphy in species of Abildgaardieae, its persistence on or detachment from the fruit might have emerged repeatedly during this clade evolution and might not be a suitable character for genera delimitation.     

Starch grain morphology of the seagrasses Halodule wrightii, Ruppia maritima, Syringodium filiforme, and Thalassia testudinum

Starch grains are a ubiquitous component of plants that have been used in tandem with phytoliths, pollen, and macrofossils to reconstruct past floral diversity. This tool has yet to be fully explored for aquatic plants, specifically seagrasses, which lack phytoliths and are rarely preserved as macrofossils or pollen. If starch grains in seagrasses are morphologically distinct, this method has the potential to improve seagrass identification in the fossil record in such cases where its starch is preserved (e.g. scratches and occlusal surfaces of tooth enamel from seagrass consumers). The goals of this study were twofold: (1) to determine if starch is present in seagrass material and (2) to assess how starch grain morphology differs between different seagrasses.This study focused on four abundant and ecologically distinct seagrasses from the Caribbean: Halodule wrightii, Ruppia maritima, Syringodium filiforme, and Thalassia testudinum. Starch grains were observed in all species except S. filiforme. Grains from H. wrightii are typically observed in side-on orientation, are sub-round to angular, and are fairly small (3-19 μm, end-on). Grains of R. maritima are small spherical grains (4-8 μm) that have a centric hilum and a straight extinction cross with a median angle between the arms of 90°. Grains from T. testudinum are large (9-31 μm, end-on), conical in side-on and round/sub-round in end-on orientation, have a slightly eccentric hilum with an obvious particle, and prominent lamellae.Visual assessment and comparative statistics demonstrate that the morphology of starch grains from T. testudinum, R. maritima, and H. wrightii are significantly different. With more extensive research, there is potential for the positive identification of starch grains from an unknown seagrass. The ability to identify seagrass from starch grains could facilitate the identification of seagrasses in the fossil record and supply information on seagrass evolution and distribution, climate effects on seagrass distribution, and the diets of seagrass consumers.