红树族植物次生木质部附物纹孔的电镜观测

应用扫描电子显微镜详细观察了红树族4属、10种、1变种植物次生木质部管状分子附物纹孔的分布和形态, 应用Carnoy 2.0软件和扫描电镜下采集的照片, 测定了管间梯状附物纹孔丰富度指标和管间梯状纹孔数量特征指标。结果显示, 红树族植物次生木质部管状分子侧壁具附物纹孔。所观察的植物附物纹孔的分布和形态变化大。附物纹孔丰富度指标与管间梯状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随纹孔口面积百分比的增大而增大。据此推测, 红树族植物附物纹孔丰富度与纹孔几何构造及数量特征有关。附物纹孔是红树族植物稳定存在的一个木材解剖性状。综合生态-系统演化的观点, 红树族植物具附物纹孔可能是受系统演化关系控制的生态适应结果。     

梣属11种植物次生木质部附物纹孔的电镜观测

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。     

Seed morphology,presence of areoles and water entry at imbibition of <i>Vicia dasycarpa</i> Ten. cv. Tolse F.C.A

The morphological characteristics of the seeds of Vicia dasycarpa Ten. cv. Tolse FCA were studied in relation to the area of imbibition water entry and were considered the presence of areoles. Seeds were analyzed using a stereo, optical and scanning electron microscope (SEM). The determination of the initial water entry area was carried out by immersing the seeds in a solution of tetrazolium (1%). This study showed that this species has seeds with a halo framing the hilum, an inconspicuous dry aril and a deltoid micropyle. The seedcoat pattern is papillose. The tracheid bar is surrounded by a ring of parenchymatous cells, and the tracheids show slight warty and non-vestured pits. It was confirmed the presence of an endospermic radicle pocket that surrounds and protect the radical tip. Two pairs of cotyledonar areoles were identified. It was established that the entry of water during imbibition starts in the area of the lens -having cracks- and moves in the sagittal plane. Both citological characteristic of tracheid bar and areoles presence show an apomorfous state between the Papiplionoids.     

What the Penaeaceae alliance (Myrtales) tells us about the nature of vestured pits in xylem

Molecular studies indicate that Penaeaceae, Oliniaceae, and the monospecific families Alzateaceae and Rhynchocalycaceae form a clade of Myrtales. Of these four families, Penaeaceae have tracheids with vestured pits, whereas the others have septate fibers lacking vestures; all have vestured pits in vessels. Tracheid presence in Penaeaceae may be related to the arid South African habitats of the family. Presence of vestures on tracheids in families with vestured vessel pits is one indication that imperforate elements are tracheids and are conductive cells, whereas fiber-tracheids and libriform fibers are non-conductive. Tracheids occur widely in angiosperms and may be plesiomorphies or apomorphies. Combretaceae, the first branch of the Myrtales clade, has a great diversity of vesture features in vessels compared to the Penaeaceae alliance families. Alzatea has vestures that spread over the inside of the vessels, whereas in most taxa of the alliance, vestures are confined to the pit cavities and pit apertures. Vestures in the alliance tend to be globular in shape, and are bridged together by strands of wall material. Lignotubers and roots in Penaeaceae have vestures much like those in stems. Only a few species and genera (notably Alzatea) of the alliance have vesture features the pattern of which correlates with the current taxonomic system. Vestured pits should be viewed from the inside surface of vessels as well as the outer surface, and although sectional views of vestured pits are infrequent, they are very informative. Studies that explore diversity from one order or family to another are needed and offer opportunities for understanding the evolutionary significance of this feature.     

两种麻黄根与茎次生木质部的解剖与进化和干旱环境的关系

用光镜及扫描电镜对两种麻黄根、茎次生木质部进行了解剖研究,结果表明：轴向系统主要由导管和管胞组成。横向系统由细胞壁木质化了的射线薄壁组织细胞组成。导管直径甚小,多孔式穿孔板,并存在导管与管胞之间的管状分子类型,推断麻黄属是裸子植物中最早出现导管的类群;管胞中有一些两头尖、胞腔小、具缘纹孔含纹孔塞的长分子,可视作纤维状管胞,使管胞的输导作用被削弱,而支持功能被加强;射线异型多列,已不具备裸子植物具较窄射线的特点。导管与管胞并存,恰好起到了一般沙生被子植物具宽窄两种类型的导管、复孔率高等典型的对干旱环境的适应特征的作用,茎中导管分子的长度和宽度均小于根,这与茎部需要较强的机械支持力相一致。     

Vessel elements present in the secondary xylem of Trochodendron and Tetracentron (Trochodendraceae)

For almost 150 years, the two monotypic genera Trochodendron and Tetracentron (Trochodendraceae) have been considered to share an unusual and primitive feature in angiosperms - the lack of vessels in their wood. Therefore, they have been classified in a basal position in the angiosperms. Our observations by light microscopy, low-vacuum environmental scanning electron microscopy (ESEM) and high-vacuum scanning electron microscopy (SEM) both in fresh and FAA-fixed materials consistently showed the presence of tracheary elements differentiated into two types in both genera. In Trochodendron, the tracheary elements can be divided into perforate vessel elements and imperforate fiber-tracheids and tracheids. The vessel elements show end and lateral walls. The pits on the end walls are elongate- broadened and do not have membranes or only a few remnants of them forming the perforation plates. The fiber-tracheids show crossfield pit pairs and sharp ends, and the tracheids show bordered pits. In Tetracentron, the tracheary elements comprise vessel elements and fibers. The vessel elements are similar to those of Trochodendron, whereas the fibers have no crossfield pit pairs but, rather, elliptical pits and sharp ends. Thus, both Trochodendron and Tetracentron are vessel bearing rather than vesselless, although their vessel elements are primitive.     

A New Species of Araucarioxylon Kraus from the Early Early Permian,Nei Mongol,China

A kind of silicified fossil wood with mixed pits on the radial tracheid wall is described. The fossil wood was collected from the top of Taiyuan Formation (early Early Permian) in Wuda Mining District, Nei Mongol. Compared with the Paleozoic fossil woods in the world, it is put into Araucarioxylon Kraus and named as A. laoshidanense sp. nov. Based on the character of possessing mixed pittings (alternate and opposite pittings) on the radial tracheid wall, the fossil wood is believed to be one of the unknown primitive conifers.Diagnosis of the new species: Only secondary xylem preserved and consisting of axial tracheids and rays. Growth ring boundary, resin duct and axial parenchyma absent. One to Four (commonly 2or3) seriates of bordered pits mostly alternate but sometimes opposite）on the radial tracheid wall. One to Four (commonly1, rarely2 to 4) Cupressoid pits in each cross-field. Rays usually uniseriate, sometimes partly-biseriate and 2 to 39 (mainly3-5) cells high.     

Pit membranes in tracheary elements of Rosaceae and related families: new records of tori and pseudotori

The micromorphology of pits in tracheary elements was examined in 35 species representing 29 genera of Rosaceae and related families to evaluate the assumption that angiosperm pits are largely invariant. In most Rosaceae, pit membranes between fibers and tracheids frequently appear to have amorphous thickenings with an irregular distribution. Although these structures are torus-like under the light microscope, observations by electron microscopy illustrate that they represent "pseudotori" or plasmodesmata-associated thickenings. These thickenings frequently extend from the periphery of the pit membrane and form a cap-like, hollow structure. Pseudotori are occasionally found in few Elaeagnaceae and Rhamnaceae and appear to be related to species with fiber-tracheids and/or tracheids. True tori are strongly associated with round to oval pit apertures and are consistently present in narrow tracheary elements of Cercocarpus (Rosaceae), Planera (Ulmaceae), and ring-porous species of Ulmus and Zelkova (Ulmaceae). Vestured pits with homogenous pit membranes are reported for Hemiptelea (Ulmaceae). The homoplastic nature of pit membrane characteristics may be related to functional adaptations in terms of safety and efficiency of water transport or may reflect different developmental processes of xylem elements. These observations illustrate that there is more variation in angiosperm pits than previously thought.     

The anatomy of lotus fibers found in petioles of Nelumbo nucifera

Lotus fibers are the isolated helical secondary cell wall thickenings from tracheary elements of lotus (Nelumbo nucifera Gaertn) petioles. In this study the anatomical characteristics of lotus petioles and microstructures of tracheary elements were studied using light microscopy (LM) and scanning electron microscopy (SEM). The results show that vascular bundles of lotus petioles are scattered throughout ground tissue. Their tracheary elements are of various sizes and there are several patterns of secondary wall thickening present. However, only secondary thickening in a ribbon-like helical pattern can be drawn out from the petiole to form lotus fibers for subsequent utilization. Study of the microstructure of the tracheary elements reveals that there are two pit structures present in the end walls in addition to pits with intact pit membranes: those with porose or web-like remnants pit membrane and those that lack pit membranes. This is an indication of the transitional stage between tracheids and vessel elements. This study provides supportive evidence that lotus fibers are found in both helically thickened tracheids and helically thickened primitive vessels.     

Further observations on hydrolysis of the cell wall in the xylem

Summary Hydrolyzed walls (birefringent, Periodic acid/Schiff negative, remnants of primary walls that also lack polyuronides with free carboxyl groups) are demonstrated in the primary xylem of wheat and bean leaves. Walls with similar properties have been found in the primary xylem of a variety of tissues from different species, and are believed to be ubiquitous. It is shown that the pit membrane of intervessel pits between tracheary elements of willow is also a hydrolyzed wall. Combined with the observation byLiese (1965) it seems likely that the removal of non-cellulosic polysaccharides from primary walls unprotected by lignin is a general phenomenon that occurs late in the autolysis of all tracheary elements. Parenchyma cells that abut autolyzing tracheary elements appear to react to hydrolytic attack in a number of ways that are illustrated and discussed.     

Distribution of stizolamine in some leguminous plants

The seeds of 38 species of 29 genera in 21 tribes of the Leguminosae were screened for stizolamine. It was detected in 19 species of the subfamily Lotoideae. Its occurrence in Lotoideae was wide (82% in tribes, 56% both in genera and species) but sporadic. The content was fairly varied (0·249–9540 nmol/g of seeds), the largest amount occurring in Stizolobium hassjoo.     

Wood anatomy of Rauvolfioideae (Apocynaceae): a search for meaningful non-DNA characters at the tribal level

Wood anatomical studies in the economically important Apocynaceae or dogbane family are fragmentary. This study represents a first attempt to unravel the phylogenetic significance and major evolutionary trends in the wood of the family, using existing and new microscopic wood observations within the large subfamily Rauvolfioideae. On the basis of LM and SEM observations of 91 species representing all 10 currently recognized tribes, we found that most of the tribes are characterized by a unique combination of wood characters, such as vessel grouping, vessel element length, fiber type, frequency of uniseriate rays, and fused multiseriate rays. Climbing rauvolfioid taxa can generally be distinguished from erect species by their wider vessels, tendency to form paratracheal axial parenchyma, presence of tracheids, and occurrence of laticifers in rays. With respect to the entire family, there is a general phylogenetic trend toward shorter vessel elements, a higher proportion of vessels in multiples and more vessels per multiple, higher tracheid abundance, more paratracheal parenchyma, and fewer cells per axial parenchyma strand in the more derived Apocynaceae. Most of these evolutionary trends are likely to be triggered by drier environmental conditions and/or shifts from an erect to a climbing habit.     

内蒙古早二叠世早期南洋杉型木属一新种

报道了一种具混合型纹孔（互列式纹孔和对列式纹孔）的化石本。化石木产自内蒙古乌达矿区老石旦矿附近太原组上部,地质时代为早二叠世早期。经比较,确认为南洋杉型木属（Ａｒａｕｃａｒｉｏｘｙｌｏｎ Ｋｒａｕｓ）一种新;老石旦南洋杉型木（Ａｒａｕｃａｒｉｏｘｙｌｏｎ ｌａｏｓｈｉｄａｎｅｎｓｅ ｓｐ．ｎｏｖ．）．根据混合型纹孔的存在及其他特征,认为新种可能代表了一种原始的松杉类植物的木材化石。主要特征：仅保存     

Vestured pits and vestured vessel member walls in some Indian dicotyledonous woods

NAIR, M. N. B. AND MOHAN RAM, H. Y., 1989. Vestured pits and vestured vessel member walls in some Indian dicotyledonous woods. The woods of 144 taxa belonging to 38 families of angiosperms were examined for vestured pits and vestured vessel member walls using scanning electron microscopy. Vestured pits are present in 66 taxa (belonging to ten families) and vestured vessel member walls occur in only six taxa (belonging to three families). In Ehretiaceae and Euphorbiaceae vestures are present only in certain vessel members. In Wrighlia tinctoria , perforation plates containing vestures have been observed in addition to the presence of vestured pits. A classification of vestured pits based on their morphology and distribution is proposed by us. In all the types of vestured pits, vestures are present on the margin of the outer pit aperture or on the pit chamber wall. Occasionally, they are present in the pit canal, on the margin and in the vicinity of the inner pit aperture and rarely over the inner walls of the vessel members. The functions of vestured pits are not clear, although several suggestions are made. Whether or not these structures affect wood processing is not presently understood. It appears that vestured pits and vestured vessel member walls have diagnostic rather than phylogenetic value.     

PARAVEINAL MESOPHYLL IN CALLIANDRA TWEEDII AND C. EMARGINATA (LEGUMINOSAE; MIMOSOIDEAE)

Paraveinal mesophyll (PVM) in Leguminosae, subfamily Mimosoideae, was first reported in 1894 but never described in detail before now. We cleared, and sectioned in resin, leaflets of Calliandra tweedii and C. emarginata (Tribe Ingeae). Lamina anatomy in both species is very similar: one palisade layer, two to three spongy layers, and the horizontal veinal network with its interconnected PVM in between. PVM is a unistratose cellular lacework extending between veins and attached medianly along each flank of all veins. PVM cells have a normal complement of typical chloroplasts similar to other mesophyll cells. Most veins are ensheathed by fibers except for an extended lateral slit along each flank where the PVM is attached; a parenchymatous bundle sheath is therefore lacking. All vein endings lack phloem, although the tracheary elements of some vein endings are flanked by one or two long, slender, seemingly undifferentiated cells. Occasional small gaps occur between the PVM cell wall and adjacent tracheary elements, which expose xylem directly to mesophyll intercellular space. PVM anatomy of Calliandra, including its physical relationship to the various vein orders, differs in some important respects from PVM of the few other leguminous and nonleguminous species studied anatomically in any detail.     

The Secondary Xylem Anatomy of 6 Desert Plants of Caragana

The structures of secondary xylem of 6 species of Caragana, which grow in desert regions of Northwest of China, are described in details. The main quantitative characters are compared with species. And a key to the identification of wood structures of 6 species is given. The main similarities of secondary xylem of these 6 species are as follows: vessels per mm2 very numerous, percentage of multiple vessels high; vessel elements very short, perforations simple and in almost horizontal end walls; intervessel bordered pits alternate and vestured, and vessels with spiral thickenings. Libriform fibres are very short, and usually with thick end walls, and with simple pits. Rays are heigh to very low, and with multiseriate and uniseriate, and with heterogeneous type Ⅰ and Ⅱ. In addition, there are differences in other characters, e.g. vessel distribution, amount of axial parenchyma and distribution, ray frequency, crystals present or absent, and crystal distribution, if present. These differences can be used as the anatomical characters to identify the wood structures of the 6 species. In this article we also discuss the relation between the structure of xylem elements and the environmental influences.     

WOOD ANATOMY OF BUBBIA (WINTERACEAE), WITH COMMENTS ON ORIGIN OF VESSELS IN DICOTYLEDONS

Quantitative and qualitative features of wood anatomy are reported for ten collections of seven species of Bubbia. Variations on the basic plan for Winteraceae can be interpreted in terms of taxonomic and ecological distinctions. Tracheid length is correlated with plant size and habit: tracheids are shortest in shrubs. Tracheid wall thickness and ray cell wall thickness distinguish species. Ray cell procumbency and multiseriate ray width increase with age. Growth rings occur only in a species from stream margins. SEM studies reveal absence of a warty layer within tracheids. Helical thickenings are absent. Presence of these two features in Pseudowintera may be correlated with the cool temperate habitats of that genus. Overlap areas of tracheids in Bubbia show various degrees of scalariform pitting, ranging from none (B. semecarpoides) to abundant presence (B. balansae). Perforation-like pits in tracheids of the latter prove, with SEM studies, to have pit membranes containing porosities less than 1 μm in diameter. Scalariform pitting on overlap areas is absent in earlier secondary xylem and increases during later secondary xylem. Scalariform lateral wall pitting can occur in abnormally wide tracheids formed after pauses in cambial activity. These facts show that primitive dicotyledon woods like those of Bubbia can activate genetic information for scalariform end wall patterns and lateral wall pitting such as primitive vessels show without the intervention of paedomorphosis. Paedomorphosis in dicotyledon woods is held still to apply only to special herbaceous and herblike growth forms, not to primarily woody plants. Progenesis (in xylem, loss of secondary xylem) is not held to be necessary to account for the scalariform patterns seen in tracheary elements of primitive dicotyledons. Reasons are given for rejection of the hypothesis that Winteraceae and other woody dicotyledons (Amborella, Sarcandra, Tetracentron, Trochodendron) are secondarily vesselless.     

国产对囊蕨亚科(蹄盖蕨科)植物的管状分子

利用扫描电镜观察了国产蹄盖蕨科(Athyriaceae)对囊蕨亚科(Deparioideae)10种植物及双盖蕨属(Diplazium Sw.)3种植物根状茎的管状分子。结果显示, 这些管状分子端壁和侧壁的形态及结构分别相同且侧壁具有穿孔板(多穿孔板)。根据穿孔板的形态特征, 将该亚科的管状分子分为5种类型: (1)梯状穿孔板, 无穿孔的二型性现象; (2)梯状穿孔板, 有穿孔的二型性现象; (3)网状穿孔板; (4)梯状-网状混合的穿孔板; (5)大孔状穿孔板。按照纹孔膜残留的程度又可分为3种: 部分区域有完整的纹孔膜、残留呈网状或线状以及很少或无纹孔膜残留。结合前人的研究资料, 发现蕨类植物的管状分子与被子植物的导管分子在形态和输导机理上存在明显差异, 管胞和导管分子不能仅仅根据纹孔膜的存在与否来确定, 而应根据穿孔板存在于端壁还是侧壁进行判断, 即穿孔板仅存在于端壁的管状分子为导管分子; 端壁和侧壁形态及结构分别相同, 有或无穿孔板的管状分子为管胞。由此可以推测蕨类植物和裸子植物中输导水分和矿物质的管状分子主要为管胞。单叶双盖蕨属(Triblemma(J. Sm.) Ching)与双盖蕨属管状分子的特征并不相似, 显示了将单叶双盖蕨属从双盖蕨属独立出来归入对囊蕨亚科的合理性。根据管状分子的特征, 推测假蹄盖蕨属(Athyriopsis Ching)和蛾眉蕨属(Lunathyrium Koidz.)可能是比较进化的属, 而介蕨属 (Dryoathyrium Ching)相对比较原始, 单叶双盖蕨属的系统位置应介于假蹄盖蕨属与介蕨属之间。     

凤尾蕨属5种植物孢子体形态研究

采用光学显微镜对凤尾蕨属5种植物孢子体形态特征进行观察和分析,以探讨该属植物的形态和亲缘关系,为凤尾蕨属的系统分类提供新的资料和依据.结果显示,该属5种植物的基本气孔类型为腋下细胞型和极细胞型;叶脉类型为无网眼的羽状分离型;副叶脉呈一回分叉平行分布;5种植物的维管束木质部多为单柱型管状中柱,也有部分双柱型网状中柱,管状分子中均有导管分子存在,仅在蜈蚣蕨和银脉凤尾蕨中发现管胞,其中井栏边草无纹孔膜残余.研究表明,蜈蚣蕨和银脉凤尾蕨较为原始,井栏边草、溪边凤尾蕨、紫轴凤尾蕨关系更近,也更为进化.     

Cytoskeletal organization during xylem cell differentiation

The water and mineral conductive tube, the xylem vessel and tracheid, is a highly conspicuous tissue due to its elaborately patterned secondary-wall deposition. One constituent of the xylem vessel and tracheid, the tracheary element, is an empty dead cell that develops secondary walls in the elaborate patterns. The wall pattern is appropriately regulated according to the developmental stage of the plant. The cytoskeleton is an essential component of this regulation. In fact, the cortical microtubule is well known to participate in patterned secondary cell wall formation. The dynamic rearrangement of the microtubules and actin filaments have also been recognized in the cultured cells differentiating into tracheary elements in vitro. There has recently been considerable progress in our understanding of the dynamics and regulation of cortical microtubules, and several plant microtubule associated proteins have been identified and characterized. The microtubules have been observed during tracheary element differentiation in living Arabidopsis thaliana cells. Based on this recently acquired information on the plant cytoskeleton and tracheary element differentiation, this review discusses the role of the cytoskeleton in secondary cell wall formation.