瘤足蕨属(Plagiogyria)植物叶柄和羽片横切面解剖学特征及分类学意义

该文采用光学显微镜,首次对九种瘤足蕨属植物的叶柄和羽片横切面进行了解剖学比较研究。结果表明:九种瘤足蕨属植物在叶柄中部横切面的表皮、基本组织和中柱以及营养叶羽片的表皮、叶肉和主脉等结构特征是相似的,如叶柄中部横切面的表皮不被毛或是鳞片,表皮细胞形状呈类圆形,具有厚壁组织,中柱为周韧型维管束;营养叶羽片横切面的气孔只分布于下表皮,表皮细胞形状呈扁平状,主脉的结构类型属于周韧型维管束。在系统的演化中,瘤足蕨与桫椤科植物有一定的亲缘关系,两者既有相似的特征但也表现出一定的差异,支持瘤足蕨属是一个自然分类的观点。九种瘤足蕨属植物叶柄中部横切面形状有梯形、椭圆形和三角形,叶柄中部横切面维管束的形状成"U"字形、"V"字形或"品"字形;维管束数目1个或3个;维管束结构中的木质部成"八"字形、"U"字形或"一"字形;羽片主脉下侧形成了以三角形、弧形或梯形的突起;叶柄中的木质部形态有两种,即典型的海马形状以及非典型的海马形状,其中典型的海马形状的特点为叶柄的木质部两侧都呈现弯曲成钩的形态,非典型的海马形状特点为2个木质部束的两侧都未出现弯曲成钩的形态或者是其中的一个木质部一端无弯曲成钩的形态,这些形态解剖特征稳定且具类群特异性,为瘤足蕨属植物的分类和系统学研究提供了新的依据。同时,依据其叶柄和羽片横切面解剖叶柄学特征列出了瘤足蕨属植物分种检索表。     

木犀属植物叶柄的比较解剖学研究

对木犀属(Osmanthus)26种植物叶柄的解剖结构进行了研究.结果表明,木犀属植物叶柄的解剖特征存在比较丰富的变异,叶柄横切面形状有3种类型(U型、V型、Y型),周缘波状、浅波状或近平滑;表皮毛有或无;维管束一般为1大2小,维管束轮廓在种问变异丰富,维管束类型有周韧、近周韧、外韧3种;小叶月桂、牛矢果、厚边木犀、美洲木犀叶柄中央具髓腔,部分种叶柄有硬化细胞或石细胞存在.木犀属植物叶柄的解剖结构特征比较稳定,可作为该属的分种特征.     

8种蒲公英属植物叶柄解剖学特征与分类学意义

采用石蜡切片法在光学显微镜下观察8种蒲公英属(Taraxacum)植物叶柄中部横切面的解剖特征.结果表明:8种蒲公英属植物不同种叶柄中部横切面形状不同,可分为椭圆形、长椭圆形和扁椭圆形.维管束类型可分为两大类,周韧和近周韧,且每种蒲公英的维管束数目和大小都不尽相同.这些特征在种之间差异比较明显,可作为种间分类鉴定的重要依据,并为蒲公英属植物亲缘关系鉴定提供了解剖学证据.     

四川藁本属植物果实和叶柄解剖学研究

对四川省藁本属5种植物的叶柄及果实进行了解剖研究,结果表明:藁本属植物的果实分为近两侧压扁和背腹压扁两种类型,背棱每棱槽内油管总数多为1~4个,合生面油管总数4~8个,在少数种间有一定的差异;胚乳背面微微隆起,腹面平直或微凹,如多管藁本,胚乳向内微凹;在蕨叶藁本中,胚乳占很大的比重,胚乳形状有很明显的个体差异.果实的压扁程度、油管特征、胚乳的形状等特征可以作为确定本属植物种间关系的依据.叶柄横切面类型多样,包括圆型、U型和V型,其中U型植物3种,占60%;近轴面除蕨叶藁本外,都具有沟槽;膜苞藁本和抽葶藁本中不具有髓腔,其他种类具髓腔,且大小、形状略有不同;横切面上维管束的数目多为5~14个,排列类型为圆型、U型、V型.以上叶柄等特征比较稳定,并且具有明显的种间差异,可以作为本属分类的重要依据.     

陕西中药细辛原植物种类及营养器官的比较解剖研究

本文报道了中药细辛在陕西的原植物种类、分布、形态特征以及营养器官的比较解剖。经对细辛原植物的营养器官作了比较解剖学研究,发现不同种类的细辛根中木质部脊数目、根被皮特点、茎中维管束数日及排列、叶柄中维管束数目及变化均有明显差异及规律,这些结构特点不仅可作为显微鉴别的主要特征,还可为植物分类及系统演化提供解剖学依据。     

中国藁本属叶柄的解剖学研究

本文首次观察了我国藁本属(Ligusticum)21种植物的叶柄解剖结构、基本特征和变异幅度。根据叶柄的维管束排列,结合横切面形状、近轴面沟槽的有无及形状、周缘的变化及髓腔的有无等特征,把21种藁本的叶柄解剖分为4个类型。依据各类型的结构特点及植物的外部形态,讨论了这4个类型可能的演化关系。作者认为滇西北地区不仅藁本属植物种类丰富,而且集中了叶柄解剖的全部类型,形态分化活跃,应是这个属的最大变异中心。     

江西产酸模属植物叶片比较解剖学研究

对江西产酸模属(Rumex L.)7种植物进行了叶形态结构的显微观察.结果表明:(1)叶片上表皮均有气孔器分布,表皮上普遍具有腺体和异细胞,叶肉中均含有晶体细胞,晶体类型为簇晶;(2)下表皮细胞特征及气孔类型、叶肉细胞的分化及排列方式、中脉维管束数目等特征具有明显的种间差异,可以作为属下种级鉴定指标;(3)小酸模在气孔类型、栅栏组织和海绵组织排列紧密程度、中脉形状及维管束数量等特征上与同属其它种类具有显著的差异,形态解剖学证据支持小酸模亚属(Subgen.Acetosella(Meisn.)Rech.)的成立;(4)根据酸模属植物气孔器类型的演化阶段,并结合孢粉学、形态学等证据,认为酸模属处于蓼科植物系统演化的较低或中等地位.通过对酸模属植物叶形态结构的比较观察,为探讨该属的系统演化关系及属下分类提供叶解剖学证据.     

河南猕猴桃属叶的解剖学研究

本文对河南猕猴桃属Actinidia 14种及变种进行了叶的解剖学观察,结果发现: (1)、果枝叶柄的中心维管束沿着由弧形到圆形,再到圆形具髓内维管束的方向演化;(2)、叶柄近轴皮层中的2个小维管束的发生和连接方式与侧脉相同,为侧脉的一部分;(3)、本属植物叶片横切面的构造可分为三种类型:栅栏组织与海绵组织分化不明显的高山阴生型,栅栏组织与海绵组织同样发达的中生型,以及栅栏组织特别发达、海绵组织退化的阳生型。引种驯化时要考虑种间这种不同的生态习性。中华猕猴桃(A.chinensis planch.)果枝叶与营养枝叶差异明显,前者叶的同化组织和输导组织都较后者发达,生产上可作为参考;(4)、脉间区由网眼缺乏一个或几个边缘、脉梢分离末端较多的不完全发育的类型,经过一个中间类型,向网眼大小、形状均匀一致的发育完全的类型过渡;(5)、中间的亲缘关系和毛基部细胞的形状、列数、排列等有密切的关系。亲缘关系较近的种类,其表皮毛也具有相似或相等的基细胞形状、列数等。     

山东产蹄盖蕨科2属植物形态解剖学的研究

采用光镜和扫描电镜对山东分布的蹄盖蕨科2属(蹄盖蕨属和假蹄盖蕨属)7种植物的根、根茎、叶柄、叶轴、叶表皮、表皮毛和孢子囊进行了形态解剖学的系统研究.结果表明,在形态解剖学方面2属植物的共同特征为:根均为无髓中柱;叶柄基部的双柱型维管束向上渐靠近联合形成1个周韧型维管束;叶上下表皮垂周壁均呈波状;气孔主要为胞环型、周胞型或极附型.2属植物的不同特征是:蹄盖蕨属植物体无毛;而假蹄盖蕨属植物叶片和叶轴上均生有腺毛;蹄盖蕨属植物根皮层外侧为薄壁细胞,假蹄盖蕨属则为棕色厚壁细胞环.研究结果表明蹄盖蕨科为一个自然分类群,并支持假蹄盖蕨属的成立.     

国产杜鹃花叶解剖与分类群

报道了分别隶属于杜鹃花属 ( Rhododendron)中 8个亚属的国产 33个种叶片的解剖特征。根据中脉维管束结构特点 :木质部与韧皮部的位置 ,木质部的形状 ,木射线排列的方式 ,可分为 5个类型 :( 1)圆形周韧维管束 ;( 2 )羽线肾形周韧维管束 ;( 3)扇线肾形周韧维管束 ;( 4 )近周韧维管束 ;( 5)下韧维管束。讨论了中脉维管束类型可能的演化趋势 :周韧维管束→近周韧维管束→下韧维管束。还讨论了 8个亚属中脉维管束所处的演化阶段     

Comparative petiole anatomy of the tribe Sorbarieae (Rosaceae) provide new taxonomically informative characters

We conducted a comparative anatomical study of the petiole of 16 taxa belonging to the tribe Sorbarieae (Rosaceae) (Adenostoma, 2 spp.; Chamaebatiaria, 1 sp.; Sorbaria, 6 spp., 3 vars., and 1 forma; and Spiraeanthus, 1 sp.) and the related genus Lyonothamnus (1 sp. and 1 ssp.). The distal, medial and proximal regions of petioles were transversely sectioned using conventional embedding and staining methods. Cuticles, crystals, trichomes and pericyclic fiber patterns were observed and studied. Three types of vascular nodal patterns were recognized: Type 1 was seen in Chamaebatiaria, Lyonothamnus, and Spiraeanthus (simple‐trace nodal pattern with slightly curved or U‐shaped vascular bundle); type 2 was found in Adenostoma (multiple‐traces nodal pattern with free vascular bundles); and type 3 was unique to Sorbaria (bundles fused to form a siphonostele nodal pattern). Some petiolar anatomical characteristics (e.g. cuticles, crystals, trichomes, vascular nodal pattern, and pericyclic fiber patterns) were found to provide useful information for taxonomic studies within Sorbarieae. On the basis of these characteristics, a dichotomous key for identification at the generic/specific level is provided. We also report a structural change in the vascular bundles from the stem‐leaf transitional zone to the leaf medial zone.     

FLEXURAL STIFFNESS ALLOMETRIES OF ANGIOSPERM AND FERN PETIOLES AND RACHISES: EVIDENCE FOR BIOMECHANICAL CONVERGENCE

Evidence for convergence in biomechanical and anatomical features of leaves (elastic modulus E, second moment of area I, taper of petioles, the longitudinal distribution of petiolar and laminar weight, and volumes of tissues) is presented based on a survey of 22 species (distributed among dicots, monocots, and ferns). In general, regardless of taxonomic affinity, petioles were found to be mechanically constructed in one of two ways: Type I petioles—as cantilevered, end-loaded beams with relatively uniform flexural stiffness (EI) (simple and palmate leaves); and Type II petioles—as tapered cantilevered beams whose static loadings (biomass) and EI increase basipetally (pinnate leaves). In general, collenchyma and sclerenchyma were found to be peripherally located in transections through Type I and II petioles, respectively. Statistical analyses within each species and among species with either type of petiole indicated that EI ≈ k₁Lp^2.98 and EI ≈ k₂Lp^2.05 for Type I and II petioles, respectively, where k₁ and k₂ are dimensional constants and Lp is petiolar length. The data are interpreted to indicate that Type I and II petioles mechanically operate to deal with static loadings in two distinct ways, such that Type II petioles function in an analogous manner to branches supporting separate leaves (leaflets). The convergence in mechanical “designs” among taxonomically distinct lineages (angiosperms and ferns) is interpreted as evidence for selection on mechanical attributes of load supporting structures (petioles).     

Carbohydrate translocation in sugar beet petioles in relation to petiolar respiration and adenosine 5'-triphosphate

Earlier studies have shown that the retarding effect of low petiolar temperatures on sucrose transport through sugar beet (Beta vulgaris L.) petioles is markedly time-dependent. Although the initial effect of chilling the petiole to near 0 C is severely inhibitory, translocation rates soon recover (usually within about 2 hours) to values at or near the control rate. In the present studies, selected metabolic parameters were measured simultaneously with translocation. No stoichiometric relationships among petiolar sucrose transport, petiolar respiration (CO₂ production), and calculated petiolar ATP turnover rates were evident. It appears that the major sources of energy input energizing carbohydrate transport in sieve tubes function mainly at either loading or unloading sites and not at the level of individual sieve-tube elements.     

Biomechanical Responses of Chamaedorea and Spathiphyllum Petioles to Tissue Dehydration

Data are presented for the mechanical responses to dehydrationof petioles from two monocotyledons (Chamaedorea erumpens andSpathiphyllum Clevelandii). These data were used to test thehypothesis that the mechanical properties (elastic modulus Eand flexural stiffness EI) of petioles from C. erumpens arealtered significantly less by dehydration than those of petiolesfrom Spathiphyllum. Dehydration, resulting from either dryingat room temperature or from submergence in various concentrationsof mannitol solutions, produced significant increases in E anddecreases in EI (due to geometric distortions) in both youngand mature Spathiphyllum petioles. Similar trends were observedfor young petioles of C. erumpens, but significantly less sofor mature petioles of this species. Regardless of petiolarage, E increased allometrically as a linear function of tissuedensity, which in turn correlated with the volume fraction oflignified tissues in petioles; however, the proportional increaseof E as a function of tissue density was significantly greaterfor C. erumpens petioles than for Spathiphyllum. Anatomicalanalyses of petiolar transections indicated that Chamaedoreapetioles had larger volume fractions of lignified tissues thanthose of Spathiphyllum and that these tissues were located tomaximize stiffness. These data (and previously reported allometricrelationships between EI and petiolar length) shed light onthe difficulties in evaluating the ‘costs’ of committingtissues to mechanical support. Petioles, biomechanics, leaf anatomy, monocotyledons     

THE ELASTIC MODULI AND MECHANICS OF POPULUS TREMULOIDES (SALICACEAE) PETIOLES IN BENDING AND TORSION

Changes attending leaf development in the mechanical behavior and elastic moduli of the petioles of Populus tremuloides Michx. were examined in terms of total leaf weight (Wt), lamina and petiole weight (Wl and Wp), petiolar length (L), and lamina surface area (A). A primary concern was the extent to which two elastic moduli (Young's modulus E and the shear modulus G) of petioles changed over time and were correlated with one another. E and G were measured by means of multiple resonance frequency spectra, and together with the dimensions of cross sections through petioles, these two elastic moduli were used to estimate the stiffness of petioles in simple bending and torsion. Petiolar bending was predicted by means of a model incorporating expressions for both the bending stiffness (El) and torsional rigidity (GJ), where I is the second moment of area and J is the torsional constant. The predictions from these models were compared to observed petiolar bendings due to Wl. Additionally, the frequency of the oscillatory motion of leaves (placed in a wind tunnel with a 1 m sec^-1 ambient wind speed, directed normal to the blade of the leaf) was determined. Results indicate that L, A, Wl, Wp, and Wt were positively correlated with the age of leaves (crudely estimated as a function of leaf plastochron index, LPI); these morphometric parameters were also correlated with the magnitudes of E and G. Also, G was positively and linearly correlated with E, and was, on the average, an order of magnitude less than E. EI and GJ were positively correlated with LPI. The relationships among E, G, EI, C and Wl, Wp, Wt are discussed in terms of leaf allometries.     

The importance of petiole structure on inhabitability by ants in Piper sect. Macrostachys (Piperaceae)

Several Central American species of Piper sect. Macrostachys have obligate associations with ants, in which the ant partner derives food and shelter from modified plant structures and, in turn, protects the plant against fungal infection and herbivory. In addition to these obligate ant-plants (i.e. myrmecophytes), several other species in Piper have resident ants only sometimes (facultative), and still other plant species never have resident ants. Sheathing petioles of sect. Macrostachys form the domatia in which ants nest. Myrmecophytes in sect. Macrostachys have tightly closed petiole sheaths with bases that clasp the stem. These sheathing petioles appear to be the single most important plant character in the association between ants and species of sect. Macrostachys . We examined the structure and variation of petioles in these species, and our results indicate that minor modifications in a small number of petiolar characters make the difference between petioles that are suitable for habitation by ants and those that are not.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 181–191.     

The Relative Magnitude of the Partial Resistances to Transpirational Water Movement in Sunflower (Helianthus annuus L.)

The effects on leaf water status of cooling entire root systemsor stem and petiolar segments were examined using hydroponicsunflower plants. Leaf water potential (^I) decreased by up to7 x 10⁵ Pa when root temperature was reduced to 10 °C orbelow; complete recovery occurred subsequently provided freezingwas avoided. Leaf water status was unaffected by cooling stemor petiolar segments unless freezing occurred, when severe irreversiblewater stress developed above the cooled zone. The leaves belowthe cooled zone were unaffected, demonstrating that the stressdid not originate from transmitted effects on the roots. Subsequent measurements using small heads of water applied toexcised petioles demonstrated that petiolar resistance was low(c. 0.04 Pa s cm_–4) except in immature and senescent petioleswhere resistance was up to 10 times larger. This trend reflectedthe developmental stage and condition of the xylem. Abrupt increases in evaporative demand, obtained by rapid reductionof relative humidity from 100% to 60 or 40%, induced transientdecreases in of approximately 4.5 and 2.5 x 10⁵ Pa, respectively,which were accompanied by simultaneous large increases in stomatalresistance. No simultaneous transient effects were observedin the stem xylem, demonstrating that the factor responsiblefor the formation of the transient foliar stress resides withinthe lamina. The results are discussed in relation to the relative magnitudeof the various partial resistances to transpirational watermovement.     

<Emphasis Type="Italic">In vitro</Emphasis> regeneration,flower and plant formation from petiolar and nodal explants of culantro (<Emphasis Type="Italic">Eryngium foetidum</Emphasis> L.)

Summary A procedure for plant regeneration, flower and plant formation from petiolar and inflorescence nodal explants of culantro is discribed. Leaf petioles were excised from young leaves of non-flowering plants while nodal explants were excised from the inflorescence. Explants were cultured in Murashige and Skoog (MS) medium alone or supplemented with 0.5μM naphthaleneacetic acid (NAA) and 0.9, 1.8, 4.5, or 9 μM thidiazuron (TDZ). All explants produced multiple shoots. In addition, nodal explants formed flowers. Shoot number, flower number and shoot length were influenced by TDZ and NAA. Rooted shoots from both types of explants were transferred to soil where plants were successfully established.     

The Effect of a Grafted Bud on Vascularization of the Petiole in Phaseolus, Datura and Lycopersicon

The radially-organized petiole of Phaseolus and the dorsiventralpetioles of Datura and Lycopersicon were used as stocks in budgrafting. Petiolar structure was examined after some weeks'growth of the scion, during which the grafted petiole came tofunction as a stem in supporting normal, vigorous shoot growthand was not abscised even at the end of the growing season.Below the graft union, reactivated petiolar cambium producedmassive amounts of secondary tissue with greatly enlarged vessels.Cambial activity was confined to the existing vascular bundlesexcept for the development of a little inter-fascicular cambiumin young, grafted Phaseolus petioles. Datura petioles woundedbelow the graft union, by a cut into the petiolar are from eitherthe abaxial or the adaxial surface and removal of a 1 cm lengthof tissue, responded by restoring the vascular are (abaxialwounds) or almost completing a vascular ring (adaxial wounds).In grafted, wounded Lycopersicon petioles the presence of deadxylem caused the separation of cambium regenerated from thecut vascular are and that arising in relation to the centralwound surface. A similar response, in which stimulated internalphloem plays an important part, occurred in certain woundedLycopersicon stems. The results are discussed in terms of thegradient induction hypothesis. graft, petiole, wound, cambium, xylem, phloem, Phaseolus multiflorus, Datura stramonium, Lycopersicon esculentum, bean, thornapple, tomato