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1.
Permineralized stems, leaves and a fertile structure assignable to Cyathotheca Taylor are described from the Late Pennsylvanian Duquesne Coal of eastern Ohio. The new material, C. ventilaria sp. nov., provides the first evidence of vegetative structures for the genus. Vegetative parts are referred to the fertile fragments based upon distinctive vascular morphology, common histological features, and close association. Stems are up to 5.0 mm in diam and have an apparently endarch dictyostele with scalariform metaxylem tracheids. Secondary xylem consists of tracheids with bordered pitting and uniseriate, parenchymatous rays 1–9 cells high. Leaves are arranged in a 3/8 pattern. They are small, pinnately-lobed, and vascularized by an U-shaped bundle. Distal to divergence, one of the apparent leaf traces becomes radial to resemble the base of a fertile structure. This implies a mode of attachment for the fructification and suggests evidence to interpret its homologies. The fertile specimen consists of laminae that diverge from a short stalk, and bifurcate distally. Laminae bear sporangia 0.6–0.7 mm in diam attached adaxially by vascularized pedicels. Spores average 36 μm in diam and are of the Kewaneesporites type. The combination of features now known for Cyathotheca exclude it from assignment to a currently-recognized major group of vascular plants, thus emphasizing that the Pennsylvanian coal swamp flora included a greater diversity than commonly is interpreted.  相似文献   

2.
A partially petrified impression of Triloboxylon ashlandicum (Aneurophytales) is the first recognized fertile axis of the genus. Identification of the fertile axis rests on the similarity of its anatomy with that of previously described vegetative specimens. Fertile organs replace some vegetative branches along part of the main axis. Fertile organs are twice dichotomized in one plane and bear elongate sporangia arranged pinnately. Vegetative branches differ in that they bear the ultimate appendages of the plant helically. The latter organs dichotomize many times in one plane. Although similar in size and morphology to the ultimate appendages, the fertile organs are homologous by position and vascular supply to the vegetative branches which they replace. Sporangia of T. ashlandicum dehisce longitudinally and terminate in an apiculate tip. Spores are unknown. Fertile organs of T. ashlandicum resemble those of other Aneurophytales and support the earlier placement of Triloboxylon in the order on anatomical grounds. T. ashlandicum differs from other Aneurophytales, however, by bearing vegetative organs at the distal end of its fertile axis.  相似文献   

3.
The Japanese otter (Lutra nippon), once inhabited in most islands of Japan, is now considered as an extinct species. Although the Japanese otter is regarded as a distinct species from the Eurasian otter (L. lutra), its phylogeny and taxonomic status are based on limited information on morphological and genetic data, and thus further clarification is required. Here, we assessed the phylogenetic relationship among the genus Lutra and taxonomic status of L. nippon by using the complete sequences of cytochrome b gene of its holotype. The present phylogenic trees supported that the genus Lutra specimens largely formed monophyletic group, with L. sumatrana as a basal to other Lutra species. Within Lutra species, L. nippon was distantly related with L. lutra. The European otter population of L. l. lutra were clustered together with its subspecies, L. l. chinensis rather than the same subspecies, Korean otter population. The discrepancy between the genetic data and traditional taxonomy justifies the necessity of reexamination of the current subspecific classification system of Eurasian otters. Level of genetic divergence between the holotype of L. nippon and L. lutra was two to three-fold lower than those among the other sister species of the Lutrinae. Based on the level of divergence between the L. nippon and L. lutra, and insufficient evidence of morphological difference between them, it is suggested that designation of Japanese otter as a separate species from L. lutra will be reconsidered.  相似文献   

4.
应用扫描电镜对梣属11种植物次生木质部导管附物纹孔的分布和形态进行了详细的观察,应用Carnoy2.0软件和扫描电子显微镜采集的照片,测定了附物纹孔丰富度指标和纹孔数量特征指标。电镜观察表明,梣属11种研究植物次生木质部导管分子侧壁附物纹孔的分布和形态变化较大,附物纹孔丰富度指标的统计描述进一步证实附物纹孔的分布变化大;3个附物纹孔丰富度指标分别与管间具缘纹孔数量特征指标的逐步回归分析表明,导管侧壁附物纹孔丰富度2个指标,即导管外纹孔口附物频率与导管纹孔腔附物频率随纹孔口面积百分比的增大而增大,推测梣属植物附物纹孔丰富度与纹孔几何构造及数量特征有关。研究认为,附物纹孔在梣属植物稳定存在,是可界定梣属植物的木材解剖性状。  相似文献   

5.
Abstract

In this study, a first record of Ribes uva-crispa L. (Grossulariaceae) – a new species of the Sicilian flora – from the Madonie Mts. is reported. The autochthonous and relict new population of Ribes uva-crispa L. (Grossulariaceae) is found on Mount Carbonara (Madonie Mts., North-Central Sicily), which is several hundred kilometers away from the Central Apenninic and the South Mediterranean locations of its distribution range. R. uva-crispa shows a distribution similar to other taxa extending from the Euro-Asiatic area to the mountains of North Africa with disjunct populations on the main Sicilian reliefs (Madonie and Nebrodi Mts.), testifying ancient phytogeographical connections. This noteworthy record adds a new species – as well as a new genus and new family – to the vascular flora of Sicily. Based on the morphological characters, the population found is to be referred to Ribes uva-crispa L. subsp. austro-europaeum (Bornm.) Bech var. glanduligerum (Lindberg) Maire.  相似文献   

6.
J. Ewald 《Plant biosystems》2013,147(3):594-603
Abstract

Based on a stratified random sample of 93 vegetation plots (144 m2) from montane and subalpine climax forests in a representative section through the Bavarian Alps, spatial pattern and environmental correlates of species density of trees, vascular understorey and epigeic bryophytes were analysed. Detecting landscape scale patterns in beta- and gamma-diversity based on interpretation of rarefaction curves proved to be difficult in a sample that had been stratified by ecological criteria. In 144 m2 plots tree species density (5 ± 2.0, max. 10) declined with elevation and increased with stand age (multiple R 2 = 0.557). The latter effect can be attributed to the secular history of game management and browsing pressure, which has hindered the regeneration of species-rich tree stands since ca. 150 yr. Species density of the forest undergrowth reached remarkably high levels for vascular plants (42 ± 12.8, max. 69) and bryophytes (14 ± 6.0, max. 30) and strongly depended on cover of the respective layer in a unimodal pattern, suggesting to separate direct and indirect effects, mediated through the mass effect, in the subsequent construction of regression models. Multiple regression (R 2 = 0.47) revealed that vascular species density is limited chiefly through low plant cover, which in turn decreases with tree cover, elevation and soil quality, and secondly by species pools that contain larger numbers of species requiring high pH and ample light. Cover and direct effects had roughly equal weight in controlling bryophyte species density (R 2 = 0.57). Biomass depended on the proportion of conifers in the tree layer and on site quality, less fertile sites tending to have higher bryophyte cover. The increase of bryophyte species density with elevation was interpreted as an effect of a pool of largely boreal-subalpine species. The increase of species density with stand age suggests dispersal limitation and deserves further study.  相似文献   

7.
Abstract

In the present study 16 populations belonging to 13 species of the genus Vernonia Schreb. were examined cytologically. In total, six different chromosome numbers, which represent three basic numbers: x = 10, x = 16 and x = 17, were found. These results include the first chromosome number reports for the following four species: V. lanifera Cristóbal & Dematt. (2n = 2x = 32), V. membranacea Gardner (2n = 2x = 34), V. salzmannii DC. (2n = 2x = 20) and V. scabrifoliata Hieron. (2n = 2x = 128). Besides, a new chromosome number was found in V. saltensis Hieron. (2n = 2x = 32), for which only tetraploid populations have been previously recorded. The data obtained in this work, along with the information available from the literature, show that the genus Vernonia in South America is heterogeneous with basic chromosome numbers that range between x = 9 and x = 19. These numbers suggest that a combination of polyploidy and aneuploidy has played an important role in the evolution of the genus.  相似文献   

8.
The genus Saussurea comprises many species with highly medicinal, religious or other economical values. The chromosome number in the genus ranges from 2n = 24 to 108, based on x = 12, 13, 16, or 17, but the primary base number is still not clear. The present meiotic study cover 8 species (14 populations) of Saussurea from the Northwest Himalayas, and add new or varied cytotypes, as an attempt to solve the enigmatic cytogenetic variations in the genus. The chromosome numbers in Saussurea auriculata (n = 16) is new to the world, while S. costus (n = 17), S. jacea (n = 17) and S. roylei (n = 17) reveal the varied cytotypes at world level. Besides, S. taraxicifolia (n = 16) is a first ever report for Indian populations. The meiotic studies on different populations reveal a substantial amount of meiotic abnormalities in the form of chromosome stickiness, un-oriented bivalents, cytomixis, laggards, etc. leading to the meiocytes with less (aneuploidy) or more (polyploidy) chromosome numbers. These abnormalities may produce unreduced pollen grains and adversely affect pollen viability. The high number of these meiotic abnormalities may be responsible for the chromosome number variation in the genus.  相似文献   

9.
10.
Sterile and fertile shoots of a microphyllous vascular plant are described from the Lower Devonian Posongchong Formation (? upper Siegenian), Yunnan Province, southern China and placed in the new taxon Halleophyton zhichangense gen. et sp. nov. The sterile axes are characterized by conspicuous, contiguous swollen rhomboidal to hexagonal leaf bases and relatively broad spatulate laminae. The relief of the leaf bases is not so pronounced in the fertile areas, which bear numerous cauline sporangia with two equal valves. In vegetative characters the new fossils, although smaller and more fragmentary, resemble Drepanophycus gaspianus but in the absence of information on the fertile parts of the latter and because of the controversy surrounding the concept of the genus Drepanophycus, we decided to erect a new genus. Its relationship to the lycophytes sensu stricto is equivocal as exact details of the relationship of sporangium with leaf and sporangium vascularization remain unknown.  相似文献   

11.
This study deals with four form or organ genera from the Upper Mississippian (Chester Series) of the Illinois Basin, and provides evidence that they were produced by a single natural genus with gymnospermous affinity. The plant remains—compressions, impressions, petrifactions, and specimens that combine compression or impression with petrifaction—allow examination of both external morphology and internal anatomy. The specimens include foliage corresponding to Rhodea, stems and petioles corresponding to Heterangium, and synangiate fructifications corresponding to either Telangium or Telangiopsis. The stems and foliage are considered parts of the same plant because of the identity of the anatomical and cuticular features of petioles attached to stem and those petioles with attached foliage. The fertile material is regarded as part of the same plant because: (1) The anatomy of axes of the fertile specimens is like that of the sterile specimens. (2) A single specimen may contain both sterile Rhodea-type axes and fertile regions. (3) Axes bearing synangia have the same size and patterns of divisions as the sterile foliage. Features that indicate lyginopterid affinities include: (1) Equal forking of the petiole. (2) Presence of fiber bands in the outer cortex and sclerotic nests in the inner part of the cortex. (3) Crowded circular bordered pits on the lateral walls of the metaxylem tracheids. (4) The presence of a small amount of secondary xylem. A variety of structural details of the stem and petiole suggest the genus Heterangium. The phyletic position of the plant that produced Rhodea, Telangium, Telangiopsis, and Heterangium is reviewed in light of such discoveries as the presence of a planated frond that lacks a lamina and the presence of both monolete and trilete microspores in a single synangium.  相似文献   

12.
Bennettitalean leaves with unusual morphology were found in the Middle Jurassic (Bathonian) deposits of Mikhailovskii Rudnik locality (Kursk Region, European Russia). This morphotype derived on the basis of Pterophyllum-like pinnate leaves by coherent coalescence of segments, through which superficial similarity of leaves of the new genus to Nilssoniopteris Nath., possessing entire leaf blade, is achieved. Each of coalescent segments was completely isolated from neighboring segments by massive cuticular wall. This character distinguishes leaves of the new genus from coherent leaves, known in other gymnosperms. The unique preservation type characteristic of plant remains of the Mikhailovskii Rudnik locality, allowed us to study some details of anatomical structure of leaf segments in the new genus. In particular, it was established, that palisade mesophyll in segments was poorly developed, and metaxylem in vascular bundles comprises tracheids with scalariform to circular bordered pits.  相似文献   

13.
To identify yeasts involved in white-colony formation on Japanese commercial kimchi products, three types of kimchi were prepared and fermented at four different temperatures. At 4 °C, yeast colonies did not appear until 35 days, while more rapid white-colony formation occurred at higher temperatures (10, 15, and 25 °C). Combination of PCR-DGGE and direct isolation of yeasts from white colonies revealed that Kazachstania exigua and K. pseudohumilis were responsible for the white-colony formation. Inoculation of the isolated Kazachstania strains into fresh kimchi successfully reproduced white-colony formation at 15 °C but not at 4 °C. Growth experiments in liquid medium revealed that Kazachstania spp. grew fast at 15 °C even in the presence of acidulants, which are commonly added to Japanese kimchi products for prevention of yeast growth. These results suggest that white-colony formation on Japanese kimchi is caused by the genus Kazachstania, and that one of important factors determining white-colony formation is its fermentation temperature.  相似文献   

14.
Three species of the red algal genus Herposiphonia (Ceramiales, Rhodomelaceae) found in Japan are described, and taxonomic features of the genus are discussed. Herposiphonia crassa Hollenberg is reported from Japan for the first time and is characterized by thick axes (200–350 µm in diameter) and determinate branches (100–200 µm in diameter), relatively short determinate laterals (400–1200 µm in length) with a large number of periaxial cells (15–19 per segment) and three (occasionally two or four) vigorously developed (1.8–2.5 mm in length by 50–75 µm in diameter basally) trichoblasts on each determinate lateral. Herposiphonia elongata Masuda et Kogame is also reported from Japan for the first time and is characterized by the conspicuous thickening growth of cystocarp‐bearing branches and spermatangial branches with an elongated sterile tip. Some newly found features of Herposiphonia fissidentoides (Holmes) Okamura are presented: the rhizoid production from the central portion of parental periaxial cells in addition to the distal end, virtual absence of vegetative trichoblasts, production of procarpial trichoblasts and spermatangial branches on fertile determinate branches on short indeterminate laterals, cystocarps sometimes with a short spur, and extremely large tetrasporangia.  相似文献   

15.
Well-preserved Marattialean fertile fronds are analyzed in this paper that come from the Cisuralian Shanxi Formation of Yongchang, Gansu Province, northwestern China. In particular, synangium in fronds and in situ spores are analyzed in the lab. Data show that the synangium of this species contains between four and five radially arranged pedicellate sporangia. The spores of this plant are small, between 21 and 30 μm, monolete and microgranulate with no visible annule. The fossils presented in this study are included within the genus Cyathocarpus. Furthermore, these spore masses and spores in situ of this genus are described in detail at the first time as a component of the Cathaysian flora. Based on comparisons with previously reported fossil records of these plants, we determined a series of differences. Thus, the fossils presented here are referred to a new species. In addition, the reproductive organs of the new fossils described in this paper provide some valuable taxonomic information. Based on the paleogeographic distribution of Cyathocarpus and the position of paleoplates in Late Paleozoic, we speculated that one of the possible migrated routes of Cyathocarpus is from the Euramerica to the North China Block and Alashan Terrane, terminating in the South China Block.  相似文献   

16.
The unique leaf structure of the genus Anemia with its upright fertile basal pinnae has been interpreted as derived from the typical fern leaf with unmodified basal pinnae. Reported herein for the first time is the leaf morphology of a species, Anemia colimensis Mickel, which shows the most primitive condition known in the genus and clearly confirms the course of evolution. The fertile pinnae are but little modified in size, lamination, and posture. Although A. colimensis has characters of two subgenera, it is shown to be a primitive element in subgen. Anemiorrhiza and not a member of subgen. Coptophyllum as previously reported.  相似文献   

17.
The radially seriate xylem of Botrychium dissectum Sprengel resembles secondary xylem, particularly that of gymnosperms, in many important details. It is derived from a layer of cells which strongly resembles a vascular cambium. Presumptive cambial initials are fusiform, and derivatives are radially seriate. The walls of the initials and derivatives have a beaded appearance when viewed in tangential section. The number of xylem elements increases in seasonal increments. Circular-bordered pit pairs occur where tracheids abut other tracheids, and specialized cross-field pit pairs occur where they abut the radially-aligned parenchyma or rays. Cambial activity in Botrychium differs from that found in seed plants and progymnosperms in not producing secondary phloem. Tracheids are less similar to those known in progymnosperms than previously assumed, and some supposed similarities may be less significant than previously assumed. The significance of these dissimilarities is unclear. The recognition that the bulk of the xylem is secondary and that protoxylem strands are arranged as sympodia suggests that Botrychium may be eustelic rather than siphonostelic.  相似文献   

18.
Pulse transit time (PTT) is the duration in which a pulse wave travels between two arterial sites within the same cardiac cycle. The aim of our study is to use PTT to examine propofol's effects on the vascular system. Methods. We collected data from 50 healthy women, between 28 and 51 years old, who underwent gynaecological surgery under general anaesthesia. The general anaesthesia was induced with propofol injection (2 mg/kg). PTT measurements were obtained from the R-wave of electrocardiogram and the pulse wave of photoplethysmograph. Two PTT values were obtained; one before (the control) and the other after propofol injection. The results were analysed by Student's t-test. Results. After propofol injection, the PTT was prolonged. The change in the PTT value from that of baseline was significant statistically (P < 0.05, by Student's t-test). The PTT change over time correlated with the degree of vasodilatation over time. Monitoring of PTT not only revealed the magnitude of vascular changes but also demonstrated the onset of vascular dilation, its peak and duration. We conclude that PTT is a useful guide in monitoring the drug kinetics of propofol.  相似文献   

19.
Cytogenetic characterization by karyotyping and determination of DNA content by flow cytometry of five species of Chrysolaena (Vernonieae, Asteraceae) was performed. This is the first study of nuclear DNA content realized in the genus. The 2C-values were compared with the ploidy level and the total karyotype length (TKL) of each species. Mitotic analysis revealed a base chromosome number x = 10 for all entities and different ploidy levels, from diploid (2n = 2x = 20) to octoploid (2n = 8x = 80). All species showed bimodal karyotypes composed of metacentric and submetacentric chromosomes. The average chromosome size (ML) varied from 1.86 μm to 2.70 μm, while the TKL ranged from 18.65 μm to 80.55 μm. The intrachromosomal asymmetry index (A1) varied from 0.27 to 0.38, while the interchromosomal asymmetry index (A2) ranged from 0.19 to 0.25. A new cytotype is reported for the first time for C. propinqua. Accessory chromosomes found in C. verbascifolia, C. cognata, C. flexuosa, and C. propinqua are also reported as new.  相似文献   

20.
Summary A phyletic tree of the genus Beta has been constructed based on EcoRI and PstI plastid DNA restriction patterns of eight species from three sections of the genus. In contrast to the remarkable morphological variability of the varieties of B. vulgaris the restriction patterns of the plastid DNA of this species were found to be almost identical. The comparison of plastic DNAs of B. vulgaris crassa fertile and sterile lines with 13 different restriction enzymes revealed only a single fragment polymorphism in the HindIII patterns. Hybridization analyses in the plastidal rDNA region revealed an interesting loss of an EcoRI restriction site in all cultivated B. vulgaris varieties in contrast to wild species. The results of the construction of clone banks for SalI and BamHI fragments of plastid DNA from fertile B. vulgaris crassa are reported and difficulties in the cloning of specific fragments are discussed.  相似文献   

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