高寒冰缘区15种藓类植物茎的形态结构研究

采用石蜡切片方法和扫描电镜方法,对高寒冰缘区生长的15种藓类植物茎的结构进行解剖学观察分析,为高寒冰缘区藓类植物在极端环境下的生存机理及其生态应用提供依据。结果表明:高寒冰缘区的15种藓类植物的茎分为表皮、皮部、中轴三部分。茎表皮细胞多为一层,长短不一,细胞壁表面粗糙,表面纹饰多为鳞片状、颗粒状、浅窝点状,表皮细胞的细胞壁加厚程度不同;皮部所占面积最大,大部分有内、外皮部的分化,细胞壁由外向内逐渐变薄,细胞由小到大又到小的整齐或镶嵌排列;中轴分化但其细胞数多少不一,细胞壁多具角隅加厚。研究认为,高寒冰缘区藓类植物具有典型的耐寒、耐旱结构特征,这些结构特征能够增强藓类植物的支撑和传导水分的作用,以抵御长期寒冷、干旱、多强风等恶劣环境;其中细胞的形状、数目、细胞表面的纹饰等微形态结构特征也具有潜在的分类学意义。     

高寒区10种青藓科植物茎结构的生态适应性

该研究对新疆天山一号冰川地区的10种青藓科植物茎的解剖结构进行了光镜和扫描电镜观察。结果表明:它们的茎横切面形状不同,表皮细胞均为1层,内、外皮部分化明显,细胞壁由外向内逐渐变薄,中轴分化明显,所占茎面积的比例、细胞厚度以及大小都不尽相同,大多数种类的细胞壁具有角隅加厚的现象。当茎干时,细胞壁表面的凹陷程度不同,其上具有不同形状的纹饰及附属物,大多数种类的表面有深浅和大小不一的小窝点分布。这些特征在不同属及不同种之间均有差异,反应出对环境的适应性,可作为青藓科植物潜在的分类依据。     

新疆5种丛藓科植物的解剖学研究

运用石蜡切片和电镜扫描技术,对5种丛藓科植物的茎、叶进行了解剖学研究。结果表明:短叶对齿藓Didymodon tectorus(C.Müll.)Saito.整个茎细胞的细胞壁均加厚,叶细胞壁凹陷呈网状,角质层纹饰条状、鳞片状和颗粒状;卷叶丛本藓Anoectangium thomsonii Mitt.茎表皮及中轴细胞壁厚,叶表面的粗疣粗糙、密集,疣上还有小孔和鳞片状纹饰;山赤藓Syntrichia ruralis(Hedw.)Web.Mohr.茎皮部细胞质浓,叶片背腹两面均密被鹿角状疣,疣上有层层叠加状纹饰和乳突;无疣墙藓Tortula mucronifolia Schweagr.茎横切面呈长圆形,叶细胞壁薄,无疣,叶背面细胞表皮较粗糙,叶腹面细胞表皮较光滑,角质层纹饰稀疏且短;长叶纽藓Tortella tortuosa(Hedw.)Limpr.茎表皮细胞壁强烈凹陷,叶细胞表面密被粗疣,疣上的角质层纹饰呈不规则鳞片状。丛藓科植物茎及叶的微观特征,为该科植物属、种的鉴定提供了重要的分类依据。     

中国美喙藓属和长喙藓属植物的茎横切结构比较研究

利用徒手切片法,对美喙藓属9个种和长喙藓属10个种进行茎横切结构的比较研究,以期为美喙藓属和长喙藓属在属间以及属内种间分类提供依据.结果表明,美喙藓属植物茎横切结构性状稳定,均具有外皮部、内皮部和中轴,中轴细胞数多在15个以下;长喙藓属植物大部分中轴分化明显,细胞数目一般为15个以上.外皮部占茎横切面的比例、内外皮部的界限、细胞壁的厚薄、中轴分化的程度等特征能给属内种间区分提供分类依据.     

四种旱生藓类植物的比较结构学观察

对新疆产的4种藓类植物茎、叶的表面及内部结构进行了观察,结果表明：尖叶大帽藓(Encalypta rhabdocarpa Schwaegr.)茎的中部结构类似于种子植物(单子叶)根的内皮层,其茎表皮也有类似于种子植物表皮毛(腺毛)的腺体。在阔叶紫萼藓(Grimmia laevigata (Brid.) Brid.)茎的中轴部,厚角组织发达,数层皮部厚壁组织也很发达。小石藓(Weisia controversa Hedw.)叶中肋之中有小形厚壁细胞。弯叶墙藓(Tortula reflexa Li)的茎呈多棱形,表皮层具很厚的“树皮状”老皮,其叶表皮细胞密被马蹄形及叉状粗疣。这些特征反映了该类群植物由低等向高等演化的趋势,并可作为分类学依据之一。     

丛藓科植物叶细胞疣和乳突的光镜观察及其分类学意义

选择中国丛藓科中具有代表性的4亚科、11属、13种,利用光学显微镜对其叶细胞的疣和乳突进行形态、大小、数量、疏密及形成等方面的观察和比较,为探讨并确定丛藓科中部分物种的系统位置提供依据。结果表明:中国丛藓科13个种植物的叶细胞疣和乳突在形态上主要分为圆疣、分叉疣和乳头状突起共3个类型,不同物种的疣和乳突在形态特征和分布上都存在一定程度的差异;通过对不同资料相应物种疣和乳突描述的比较,纠正了一些物种疣和乳突的描述错误,并提出疣和乳突的区分方法:观察叶片横切,疣是细胞壁的局部加厚或凸起,数量变化较大,而乳突是细胞壁和腔整体的膨起,每细胞仅具一个乳突。研究认为,疣和乳突是丛藓科物种叶细胞表面的稳定结构,具有重要的辅助分类功能,可利用其差异对丛藓科属间和种间的物种进行划分。     

新疆大帽藓属6种植物茎及叶的比较解剖学研究

运用石蜡切片和电镜技术,对新疆的6种大帽藓属（Encalypta Hedw.）植物的茎和叶进行解剖学观察。结果表明：高山大帽藓（E.alpina Smith.）疣多呈菱形或“柱状”密集着生在叶表面,疣上纹饰呈纵棱和小疙瘩状;裂瓣大帽藓（E.ciliata Hedw.）茎横切面为五角形, 中轴细胞角隅加厚,叶腹面的粗疣大部分集中分布在凹陷的表面细胞壁上;剑叶大帽藓（E.spathulata C.Mull.）茎横切面没出现中柱鞘,疣在基部分叉丛生,叶腹面的表皮细胞壁不凹陷;钝叶大帽藓（E.vulgaris Hedw.）没有叶尖,中肋导水细胞大,叶表面细胞壁较光滑且强烈凹陷,其壁上的乳突不明显;天山大帽藓（E.tianschanica j.c.Zhao,R.L.Hu et S.He）茎内外皮层区分明显,内皮层细胞质浓,叶背面的分叉状粗疣呈密集生长在叶腹面的星状粗疣大多集中分布在稍下陷的细胞壁上;西藏大帽藓（E.tibetana C.Mull）中肋细胞壁加厚,叶片具层层叠叠的、密集的、不规则分叉的粗疣,叶背面有些部位被带状附属物所覆盖。这6种植物叶的背、腹面均具不同程度的分叉粗疣,但粗疣的大小、着生位置、呈现的状态、疣上不同的纹饰却各不相同;中肋细胞的层数、及导水主细胞的大小、状态也大不相同,这些细微特征的观察研究可作为大帽藓属植物分类学的依据之一。     

新疆18种木灵藓属(Orthotrichum Hedw.)植物解剖结构研究

采用徒手切片法对新疆木灵藓属(Orthotrichum Hedw.)18种植物孢蒴上的气孔、茎和叶进行了比较解剖学观察。研究结果表明,木灵藓属植物茎横切结构形状稳定,由表皮和皮层组成,无中轴细胞分化;除半裸木灵藓(Orthotrichum hallii Sull.et Lesq.)外,其它种叶上部均为单层细胞;叶中部边缘外卷,叶细胞具有高度不同的分叉疣或单疣。在确定气孔显、隐型的基础上,茎和叶横切面的颜色、茎表皮和皮层细胞组成及细胞壁加厚程度、叶细胞疣的高度、叶中肋横切面的形状、中肋的宽度、细胞组成以及芽孢形态等特征可作为该属种间分类的依据。还根据18种木灵藓属植物孢蒴上的气孔显、隐型,及茎、叶的比较解剖学特征,编制了新疆木灵藓属植物的分种检索表。     

新疆18种木灵藓属(Orthotrichum Hedw.) 植物解剖结构研究

采用徒手切片法对新疆木灵藓属（Orthotrichum Hedw.）18种植物孢蒴上的气孔、茎和叶进行了比较解剖学观察。研究结果表明,木灵藓属植物茎横切结构形状稳定,由表皮和皮层组成,无中轴细胞分化;除半裸木灵藓（Orthotrichum hallii Sull.et Lesq.）外,其它种叶上部均为单层细胞;叶中部边缘外卷,叶细胞具有高度不同的分叉疣或单疣。在确定气孔显、隐型的基础上,茎和叶横切面的颜色、茎表皮和皮层细胞组成及细胞壁加厚程度、叶细胞疣的高度、叶中肋横切面的形状、中肋的宽度、细胞组成以及芽孢形态等特征可作为该属种间分类的依据。还根据18种木灵藓属植物孢蒴上的气孔显、隐型,及茎、叶的比较解剖学特征,编制了新疆木灵藓属植物的分种检索表。     

两种生境下的8种藓类植物茎结构的比较解剖学研究

对极端生境(旱生与水生)下的8种藓类植物,旱生条件下生长的虎尾藓(H edw ig ia cilia ta(H edw.)P.B eauv.)、欧黑藓东亚变种(And reaea rup estrisH edw.var.f auriei(B esch)T akak i)、长蒴紫萼藓(G rimm ia m acrothe-ca M itt.)、日本蓑藓(M acrom itrium jap on icum D oz.et M o lk)和簇生砂藓(R acom itrium aqua ticum(Schrad.)B rid.),水生条件下生长的大叶凤尾藓(F issid ens g rand if rons B rid.)、鳞叶水藓(F ontina lis squam osa H edw.)和短尖美喙藓(E urhynch ium angustirete(B roth.)T.K op.)进行了茎的横切及离析后细胞形态学的比较研究.结果表明:(1)生长在干旱条件下的5种藓类植物的茎无中轴分化,细胞壁厚;离析后可见细胞端尾和纹孔场数目多,端尾数目增多扩大了细胞间的接触表面积,纹孔场数目最多为2.60/细胞,显示出其机械组织发达,这些是对旱生生长环境的适应.(2)生长在水生条件下的3种藓类植物茎的中轴有或无,细胞壁薄;离析后可见细胞端尾和纹孔场数目少,纹孔场数目最少为0.37/细胞,茎表皮细胞壁薄且茎内有大量薄壁细胞,表明其机械组织不发达,这些特征与水生生长环境相适应.本文还对8种藓类植物茎的结构特征在分类中的应用进行了探讨,认为茎表皮、内外皮部宽度及细胞分化的比例、中轴的有或无等在属间种内的性状是稳定的,具分类学意义.     

Development of thallus axes in Usnea longissima (Parmeliaceae, Ascomycota), a fruticose lichen showing diffuse growth

? Premise of the study: While cell wall thickening in plants is generally associated with tissue maturation, fungal tissues in at least two lichens continue to grow extensively while accumulating massively thickened cell walls. We examined Usnea longissima to determine how diffuse growth shapes morphological and anatomical development of thallus axes and how the highly thickened cell walls of the central cord behave in diffuse growth. ? Methods: Fresh material was examined with light and epifluorescence microscopy and conventional and low-temperature SEM. Fixed material was embedded in Spurr's resin, microtome-sectioned, and examined with TEM and light microscopy. ? Key results: Main axes consisted essentially of bare medullary cord tissue; their characteristic morphology developed by destruction of the overlying cortex and consequent stimulation of lateral branch formation. Fungal cells of the cord tissue continually deposited wall layers of electron-transparent substances and layered, electron-dense materials that include UV-epifluorescent components. Discontinuities were evident in the outermost layers; new branch cells grew through wall materials accumulated by older neighboring cells. ? Conclusions: Sustained diffuse growth of cord tissue in U. longissima underlies the structural transformation of a corticated thallus branch into a long axis. In the cord tissue, diffuse growth may be responsible for the increasingly disrupted appearance of the older, electron-dense cell wall layers, while new wall materials are laid down adjacent to the protoplast. Cell and tissue development appeared comparable to that observed previously in Ramalina menziesii, although accumulation of wall material was somewhat less extensive and with a greater proportion of electron-dense/UV-epifluorescent components.     

Gibberellin-induced formation of tension wood in angiosperm trees

After gibberellin had been applied to the vertical stems of four species of angiosperm trees for approximately 2 months, we observed eccentric radial growth that was due to the enhanced growth rings on the sides of stems to which gibberellin had been applied. Moreover, the application of gibberellin resulted in the formation of wood fibers in which the thickness of inner layers of cell walls was enhanced. These thickened inner layers of cell walls were unlignified or only slightly lignified. In addition, cellulose microfibrils on the innermost surface of these thickened inner layers of cell walls were oriented parallel or nearly parallel to the longitudinal axis of the fibers. Such thickened inner layers of cell walls had features similar to those of gelatinous layers in the wood fibers of tension wood, which are referred to as gelatinous fibers. Our anatomical and histochemical investigations indicate that the application of gibberellin can induce the formation of tension wood on vertical stems of angiosperm trees in the absence of gravitational stimulus.     

DEVELOPMENTAL ANATOMY OF THE STEM OF WELFIA GEORGII,IRIARTEA GIGANTEA,AND OTHER ARBORESCENT PALMS: IMPLICATIONS FOR MECHANICAL SUPPORT

Changes in stem anatomy with radial position and height were studied for the arborescent palms Welfia georgii, Iriartea gigantea, Socratea durissima, Euterpe macrospadix, Prestoea decurrens, and Cryosophila albida. Vascular bundles are concentrated toward the stem periphery and peripheral bundles contain more fibers than central bundles. Expansion and cell wall thickening of fibers within vascular bundles continues throughout the life of a palm, even in the oldest tissue. Within individual vascular bundles, the fibers nearest the phloem expand first and fiber cell walls become heavily thickened. A front of expanding fibers moves outward from the phloem until all fibers within a vascular bundle are fully expanded and have thick cell walls. Peripheral vascular bundles differentiate first and inner bundles later. In the stem beneath the crown, vascular bundles and ground tissue cells show little or no size increase, but marked cell wall thickening during development for Welfia georgii. Beneath the crown, diameters of peripheral vascular bundles increase more than twofold for Iriartea gigantea, while diameters of central bundles do not increase. In Iriartea stems, ground tissue cells at the periphery elongate to accommodate expanding vascular bundles and cell walls become thickened to a lesser degree than in fibers; central ground tissue cells elongate markedly, but cell walls do not become thickened; and large lacunae form between central parenchyma cells. For Iriartea, Socratea, and Euterpe, sustained cell expansion results in limited, but significant increases in stem diameter. For all species, sustained cell wall thickening results in dramatic increases in stem stiffness and strength.     

Anatomy of vegetative organs,inflorescence axis and pedicel in the Neoregelia bahiana complex (Bromeliaceae): taxonomic and ecological importance

Delimitation of genera and species in Bromeliaceae is often problematic, for example in the Neoregelia bahiana complex which is distributed throughout the rocky fields of the Espinhaço Range, Brazil. Considering that the anatomical characterisation of different organs is potentially important for taxonomic and ecological interpretation of this complex, we analysed roots, stems (stolon), leaves, inflorescence axes (peduncle) and pedicels in individuals from different populations. In all the studied individuals, the roots are composed of velamen, a heterogeneous cortex, and a polyarch vascular cylinder with sclerenchymatous pith. The stolon features a parenchymatous cortex and collateral vascular bundles randomly distributed in the vascular cylinder. This organ may increase in diameter by the formation of new vascular bundles and a multi‐layered cork. The leaf blade has epidermal cells with U‐shaped thickened walls and peltate scales occur on the adaxial surface. The mesophyll consists of mechanical and water‐storage hypodermis and a heterogeneous chlorenchyma. The inflorescence axis and the pedicel have a parenchymatous cortex and vascular bundles randomly distributed in an aerenchyma. Some variable leaf characters, such as presence of air lacunae in the mesophyll, are related to the size of the individuals and were interpreted as phenotypic variations related mainly to sunlight incidence. In contrast, leaf characters such as lamina shape, distribution of the peltate scales, and number of cell layers forming the water‐storage hypodermis distinguish the populations of the Serra do Cabral and one population of the Diamantina (Minas Gerais) from the remaining studied populations, suggesting the existence of more than one taxon.     

丛藓科（Pottiaceae）植物叶细胞形态特征及其系统学意义

通过光学显微镜（LM）和扫描电镜（SEM）观察了17属国产丛藓科（Pottiaceae）植物叶中上部细胞的形态特征,结果表明：丛藓科植物的叶中上部细胞的形状、大小及表面形态等特征上具较大相似性;据细胞表面特征,叶细胞可分为无疣或具乳突、具圆疣以及具分枝的马蹄形疣3种类型,且该特征在丛藓科不同属、种间有较大的区别。因此,叶细胞形态特征可为丛藓科植物属级和亚科级的划分提供细胞形态学依据。     

菰适应湿地环境的解剖和屏障结构特征研究

菰(Zizania latifolia)是一种多年生挺水植物,为了探讨该植物根、茎和叶的解剖结构、组织化学及其质外体屏障的通透性生理。该文利用光学显微镜和荧光显微镜,对菰的根、茎、叶进行了解剖学和组织化学研究。结果表明:(1)菰不定根解剖结构由外而内分别为表皮、外皮层、单层细胞的厚壁机械组织层、皮层、内皮层和维管柱;茎结构由外而内分别为角质层、表皮、周缘厚壁机械组织层、皮层、具维管束的厚壁组织层和髓腔。叶鞘具有表皮和具维管束皮层,叶片具有表皮,叶肉和维管束。(2)不定根具有位于内侧的内皮层及其邻近栓质化细胞和外侧的外皮层组成的屏障结构;茎具内侧厚壁机械组织层,外侧的角质层和周缘厚壁机械组织层组成的屏障结构,屏障结构的细胞壁具凯氏带、木栓质和木质素沉积的组织化学特点,叶表面具有角质层。(3)菰通气组织包括根中通气组织,茎、叶皮层的通气组织和髓腔。(4)菰的屏障结构和解剖结构是其适应湿地环境的重要特征,但其茎周缘厚壁层和厚壁组织层较薄。由此推测,菰适应湿地环境,但在旱生环境中分布有一定的局限性。