中国早熟禾属植物部分种叶下表皮微形态的研究

通过光学显微镜及扫描电子显微镜对中国早熟禾属20种、6亚种及2变种植物的叶下表皮微形态特征进行了观察, 以明确叶表皮微形态特征在早熟禾属植物中的分类学意义。结果显示：(1)早熟禾属植物的叶下表皮长细胞多为长筒状或纺锤形,少数短筒状,细胞壁波状弯曲或近平直;脉间具有短细胞或缺如;气孔器多数常见,副卫细胞平行形至低圆屋顶形;脉上具有刺细胞或缺如,脉间刺细胞多为缺如;脉上硅细胞单生或对生,椭圆形、肾形、新月形、近方形、长方形边缘波状弯曲或结节形;部分早熟禾属植物叶下表皮存在冠细胞。(2)早熟禾属植物叶下表皮微形态特征在长细胞的形状及其细胞壁的弯曲与否、短细胞的有无及其形状、气孔器的分布与副卫细胞的形状、刺细胞的分布、脉上硅细胞的形状、冠细胞的有无这些方面存在着一定的差异,可为该属植物种间分类提供参考依据。叶表皮微形态证据支持高原早熟禾、细叶早熟禾作为草地早熟禾亚种的处理意见。     

中国看麦娘属植物叶表皮微形态研究

看麦娘属是禾本科早熟禾亚科的重要类群,中国分布有8种。该研究采用光学显微镜和电子扫描电镜,对中国看麦娘属7种植物的叶下表皮(含叶鞘下表皮)微形态特征进行观察并探讨其分类学意义。结果表明：(1)看麦娘属叶鞘下表皮长细胞的形状呈长筒状或短筒状,深波状弯曲的细胞壁,脉间短细胞密布,单生或对生,形状多为新月形或椭圆形,脉区硅细胞为椭圆形,平行形或低圆屋顶形的气孔器,看麦娘属叶鞘下表皮特征高度一致,分类价值不大。(2)看麦娘属植物叶下表皮和叶鞘下表皮的显微结构存在很大不同,看麦娘属植物叶下表皮长细胞多为长筒状或短筒状或长菱形,平周壁平直或不明显弯曲,脉间区短细胞分布或无,脉区刺毛密布,脉间区有或无刺细胞的分布,平行形的气孔器,脉区分布的硅细胞多为长方形边缘呈波状弯曲。看麦娘属植物叶下表皮的不同主要体现在脉间区长细胞的形状及平周壁的弯曲与否,脉间区短细胞出现或无,脉间区刺细胞的分布数量以及气孔器的列数。7种植物的叶表皮微形态的分类检索表据此列出。依据叶表皮微形态划分的组与根据外部特征划分的组并不完全一致。但是,由于该文仅研究了7种,叶表皮微形态对于看麦娘属的分类意义还需要更深入的研究。     

遮阴对高山杜鹃叶片解剖和光合特性的影响

为了解高山杜鹃对光能的需求和适应性,该研究以盆栽3 a生高山杜鹃品种cv. Furnivall's Daughter为材料,探讨了遮阴对高山杜鹃叶片解剖结构和光合特性的影响。结果表明:光照强度对高山杜鹃品种cv. Furnivall's Daughter叶片的气孔密度没有显著影响,其气孔密度范围在299.70~327.22个·mm~(-2)之间,但光照对气孔开度和单个气孔器的面积影响显著,100%全光照和30%全光照处理植株分别具有最小和最大的叶片气孔开度。在处理的光强范围内,随着光强减弱,叶片厚度、栅栏组织厚度、海绵组织厚度以及上、下表皮厚度逐渐降低,有利于提高叶片的光能利用效率。100%全光照处理下,高山杜鹃叶片的光饱和点(LSP)、净光合速率(P_n)、饱和光合速率(P_(max))、气孔导度(Gs)、蒸腾速率(Tr)均较低,遮阴处理有效提高了Pn、P_(max)、G_s、T_r和光能利用效率(LUE),且30%全光照处理植株的叶片光补偿点(LCP)、暗呼吸速率(Rd)最低,而LSP、P_n、P_(max)、G_s、T_r和LUE最高。这表明高山杜鹃在云南昆明地区的最适光照条件是30%左右的全光照,在高山杜鹃的栽培及应用中,应采取适当的遮阴措施以满足其生长的最佳光照条件。     

Changes of epicuticular wax induced by enhanced UV-B radiation impact on gas exchange in Brassica napus

The epicuticular wax covering on plant surface plays important roles in protecting plants against UV radiation. However, the role of epicuticular wax in affecting leaf gas exchange under enhanced ultraviolet-B (UV-B) radiation remains obscure. In the present study, different aged leaves of Brassica napus were used to analyze the responses of crystal structure and chemical constituents of epicuticular wax to UV-B radiation and the effects of such responses on gas exchange indices. Enhanced UV-B radiation significantly decreased the amount of esters in all leaves except the first leaf, amount of secondary alcohols in the second, third and fourth leaves, and amount of primary alcohols in the second and third leaves, while increased the amounts of ketones and aldehydes in the first leaf. Enhanced UV-B level had no significant effect on the amounts of alkanes and total wax in all leaves. Exposure to UV-B radiation resulted in wax fusion on adaxial leaf and stomata opening on abaxial leaf. Fusions of plates and rods on adaxial leaf surface covered most of the stomata, thereby influencing the photosynthesis in the upper mesophyll of leaves. Enhanced UV-B level significantly reduced the net photosynthesis rate (P _N) but increased the stomata conductance (g _s), concentrations of intercellular CO₂ (C _i ), and transpiration rate (E) in all leaves. Both UV-B radiation and the wax fusion induced by enhanced UV-B radiation resulted in different stomata status on abaxial and adaxial leaf surface, causing decrease of P _N, and increase of g _s, C _i and E in leaves.     

Growth under UV-B radiation increases tolerance to high-light stress in pea and bean plants

Pea (Pisum sativum L.) and bean (Phaseolus vulgaris L.) plants were exposed to enhanced levels of UV-B radiation in a growth chamber. Leaf discs of UV-B treated and control plants were exposed to high-light (HL) stress (PAR: 1200 mol m^–2 s^–1) to study whether pre-treatment with UV-B affected the photoprotective mechanisms of the plants against photoinhibition. At regular time intervals leaf discs were taken to perform chlorophyll a fluorescence and oxygen evolution measurements to assess damage to the photosystems. Also, after 1 h of HL treatment the concentration of xanthophyll cycle pigments was determined. A significantly slower decline of maximum quantum efficiency of PSII (F _v/F _m), together with a slower decline of oxygen evolution during HL stress was observed in leaf discs of UV-B treated plants compared to controls in both plant species. This indicated an increased tolerance to HL stress in UV-B treated plants. The total pool of xanthophyll cycle pigments was increased in UV-B treated pea plants compared to controls, but in bean no significant differences were found between treatments. However, in bean plants thiol concentrations were significantly enhanced by UV-B treatment, and UV-absorbing compounds increased in both species, indicating a higher antioxidant capacity. An increased leaf thickness, together with increases in antioxidant capacity could have contributed to the higher protection against photoinhibition in UV-B treated plants.     

遮荫对南美蟛蜞菊、蟛蜞菊及其自然杂交种叶片显微结构及叶绿体超微结构的影响

利用JSM-6360LV型扫描电镜和JEM-1010型透射电镜,观察了南美蟛蜞菊、蟛蜞菊及其自然杂交种新近成熟和老熟叶片的解剖结构及叶绿体超微结构。结果表明:遮荫后该杂交种与其亲本新近成熟叶片均表现为上下表皮气孔密度、叶片总厚度及上下表皮厚度、栅栏组织、海绵组织厚度减小,叶绿体肿胀变形,基粒片层垛叠程度增加,淀粉粒增多变大;遮荫后杂交种老熟叶片总厚度及上表皮、栅栏组织、海绵组织厚度增加,入侵种的下表皮厚度及本地种的上表皮厚度增加,叶绿体超微结构在遮荫后均出现严重损伤,基粒片层类囊体结构边缘溶解等。说明三种蟛蜞菊属物种及各物种不同叶龄叶片对弱光条件的响应存在差异;杂交种叶片显微及超微结构在不同光照下的变化介于亲本之间,对遮荫环境能较好适应。     

Litter decomposition and nitrogen mineralization of soils in subtropical plantation forests of southern China,with special attention to comparisons between legumes and non-legumes

Litter decomposition and nitrogen mineralization were investigated in subtropical plantation forests in southern China. The CO₂ –C release from incubated litter and the forest floor of Acacia mangium, Acacia auriculaeformis, Eucalyptus citriodora, Pinus elliotii and Schima superba stands were used to estimate relative rates of litter decomposition. Decomposition was not positively correlated with litter nitrogen. E. citridora litter decomposed most rapidly and A. mangium litter most slowly, both with and without the addition of exotic nitrogen. Aerobic incubation and intact soil core incubation at 30 °C over a period of 30 days were used to assess nitrogen mineralization of six forest soils. Although there were differences in results obtained using the two methods, patterns between legume and non-legume species were the same regardless of method. All soils had pH values below 4.5, but this did not prevent nitrification. The dominant form of mineral nitrogen was nitrate for legume species and ammonium for non-legume species. The nitrogen mineralization potential was highest for soils in which legumes were growing.     

Surface features of the leaves ofBalanophoraceae — A family without stomata?

Both adaxial and abaxial leaf surfaces were searched for stomata inBalanophora elongata, B. fungosa, Hachettea austro-caledonica, Langsdorffia hypogaea, Lophophytum mirabile subsp.mirabile, Scybalium jamaicense, andThonningia sanguinea (Balanophoraceae). Neither stomata nor guard cells were observed. The epidermal surfaces of these species are extremely diverse with respect to cell shape, cell size, and surface ornamentation, these features providing valuable systematic criteria.     

酸枣叶片结构可塑性对自然梯度干旱生境的适应特征

叶片是植物体暴露于环境中面积最大的器官,其最易感知环境变化而发生形态和结构上的改变。为探究植株叶片结构对不同生境的适应机理,研究以生长在烟台-石家庄-宁夏-新疆不同地域气候条件形成的自然梯度干旱环境中的酸枣为试验材料,应用植物显微技术研究酸枣叶片的结构的可塑性对不同自然梯度干旱环境的适应特征。结果表明:酸枣叶表皮着生有表皮毛,表皮细胞外覆有角质层与蜡质。叶肉为全栅型,栅栏组织发达,海绵组织退化,叶肉中有晶体及大量的分泌细胞。从烟台至新疆随生境梯度干旱加剧,酸枣叶片叶面积逐渐变小,叶片厚度依次增加,叶表皮角质层加厚,且上角质层厚度大于下角质层厚度;叶片上下表皮细胞长径及短径先增后降,栅栏组织总厚度和密度依次增大、层数减少,各层栅栏组织细胞的长径逐渐增加。叶脉薄壁细胞相对厚度逐渐减小,导管管径增大,晶体(草酸钙晶体)数增多。在梯度干旱环境中酸枣植株通过减小叶面积、提高栅栏组织密度、增加叶片及角质层厚度降低蒸腾作用,减少水分散失;通过增大导管管径提高水分利用率;通过增加晶体数量提高叶片机械性能,改变细胞的渗透势、提高吸水和保水能力。上述叶片结构的变化是酸枣植株长期对不同自然梯度干旱生境的适应特征。由此可知,叶片形态结构中叶面积、叶片厚度、角质层及叶肉组织(栅栏组织)随环境变化的可塑性较大。     

Stratospheric Ozone Depletion: High Arctic Tundra Plant Growth on Svalbard is not Affected by Enhanced UV-B after 7 years of UV-B Supplementation in the Field

The response of tundra plants to enhanced UV-B radiation simulating 15 and 30% ozone depletion was studied at two high arctic sites (Isdammen and Adventdalen, 78° N, Svalbard).The set-up of the UV-B supplementation systems is described, consisting of large and small UV lamp arrays, installed in 1996 and 2002. After 7 years of exposure to enhanced UV-B radiation, plant cover, density, morphological (leaf fresh and dry weight, leaf thickness, leaf area, reproductive and ecophysiological parameters leaf UV-B absorbance, leaf phenolic content, leaf water content) were not affected by enhanced UV-B radiation. DNA damage in the leaves was not increased with enhanced UV-B in Salix polaris and Cassiope tetragona. DNA damage in Salix polaris leaves was higher than in leaves of C. tetragona. The length of male gametophyte moss plants of Polytrichum hyperboreum was reduced with elevated UV-B as well as the number of Pedicularis hirsuta plants per plot, but the inflorescence length of Bistorta vivipara was not significantly affected. We discuss the possible causes of tolerance of tundra plants to UV-B (absence of response to enhanced UV-B) in terms of methodology (supplementation versus exclusion), ecophysiological adaptations to UV-B and the biogeographical history of polar plants     

Chemical Fruit Thinning in Loquat with NAAm:Dosage, Timing, and Wetting Agent Effects

Effects of an increased lead (Pb) content in soil on growth, photosynthesis (P _N) and anatomical parameters of Plantago major L. plants grown under controlled conditions were studied. The total dry weights of plants at 500 and 2000 mg kg^–1 Pb in soil were correspondingly 70% and 54% of those of control plants. A reduced leaf area and changed leaf structure caused a decrease in P _N in the whole plant. The specific leaf weight (SLW) increased as compared with that of control plants. An increasing Pb content in soil caused a larger number of chloroplasts and larger sizes of protoplasts, a decrease in the chlorophyll a+b contents and a larger number of stomata per unit leaf area based both in adaxial and abaxial epidermis, as compared with control plants. However their conductance was from 40% to 50% lower than that in control plants. It was noted that the dimensions of conducting bundles decreased mainly because of the reduced xylem area. The lower functional activity and the changes at different structural levels of the photosynthetic apparatus caused a decrease in the growth rate of plants at a high Pb content in soil.     

罗汉松雌雄株叶形态结构的比较研究

该研究以雌雄异株植物罗汉松(Podocarpus macrophyllus)成熟叶为研究材料,采用光学显微镜、扫描电镜和透射电镜观察比较罗汉松雌、雄植株叶在形态、显微结构和超显微结构的差异,以明确罗汉松雌、雄株在进化过程中叶对环境功能的适应性。结果显示:(1)罗汉松雌株的叶片大于雄株,且两者的叶长、叶宽和叶柄长差异极显著,而叶柄厚、叶面积、叶体积、叶质量、比叶重(SLW)、面积与体积之比(A/V)等性状无显著差异。(2)雌株叶片的气孔相对较大,密度较高,且雌株气孔宽度极显著大于雄株;雌株叶片的上表皮长细胞宽度和下表皮短细胞宽度均显著大于雄株,但雌株叶片的上表皮长细胞和短细胞的长度则显著小于雄株。(3)罗汉松雌株叶片的栅栏组织厚度、海绵组织厚度、传输组织长度和宽度、上下角质层厚度、维管束厚度、叶片紧密度(CTR)及疏松度(SR)均极显著大于雄株,而雌株的下表皮厚度极显著小于雄株,但雌雄株叶片的上表皮细胞厚度和栅海比差异不显著;雌株叶片的栅栏组织细胞、叶绿体和线粒体均较雄株的长而细,且雌株的线粒体宽度极显著小于雄株。(4)罗汉松雌株叶片上表皮蜡质饰纹、下表皮角质层纹饰、气孔外拱盖纹饰及内缘类型等4个微形态特征与雄株差异明显。(5)叶表皮蜡质层能谱分析表明,罗汉松雌株叶片含有9种元素,而雄株叶片仅有8种(缺少K元素);且雌株的Si元素含量高于雄株,而雄株的C、O、Na、Mg、Al、Ca和Au元素含量均高于雌株。研究表明,罗汉松雌、雄植株之间存在明显的第二性征,雌株叶片结构有助于提高光合等性能以满足生殖需求;罗汉松雌、雄株叶形态结构的差异是其长期进化形成的有利于物种繁衍的适应策略。     

Stomata in some species of genus <Emphasis Type="Italic">Arum</Emphasis> from the Eastern Slavonia and Baranya region

Types and the number of stomata in the following Arum species: Arum italicum Mill., Arum maculatum var. maculatum L. and Arum maculatum var. immaculatum L., Arum alpinum var. pannonicum Terpo. and Arum alpinum var. intermedium Schur. in three different locations in Zablaće, Normanci and Bilje were investigated. The most prevalent stomata type at both upper and lower epidermis for each Arum species was mostly stomata type paracytic, followed by hexacytic, tetracytic or brachyparacytic as far as locality is concerned. Helicocytic type was more prevalent in Arum alpinum var. pannonicum Terpo. and Arum alpinum var. intermedium Schur. at Bilje. Other stomata types were very rare. A striking regularity in the occurrence of stomata types was not found within a single species. Some stomata types, however, were found either at adaxial or abaxial epidermis or were not present at all. The number of stomata per square mm varied from 25 to 651. A statistically significant difference in the number of stomata per square mm at upper and lower epidermis among Arum species was determined in locations Zablaće and Normanci, whereas no statistically significant differences were found in location Bilje.     

Stomatal responses of Argenteum — a mutant of Pisum sativum L. with readily detachable leaf epidermis

Epidermis is easily detached from both adaxial and abaxial surfaces of leaf four of the Argenteum mutant of Pisum sativum L. The isolated epidermis has stomata with large, easily-measured pores. Hairs and glands are absent. The density of stomata is high and contamination by mesophyll cells is low. In the light and in CO₂-free air, stomata in isolated adaxial epidermis of Argenteum mutant opened maximally after 4 h incubation at 25°C. The response of stomata to light was dependent on the concentration of KCl in the incubation medium and was maximal at 50 mol m^-3 KCl. Stomata did not respond to exogenous kinetin, but apertures were reduced by incubation of epidermis on solutions containing between 10^-5 and 10^-1 mol m^-3 abscisic acid (ABA). The responses of stomata of Argenteum mutant to light, exogenous KCl, ABA and kinetin were comparable with those described previously for stomata in isolated epidermis of Commelina communis. A method for preparing viable protoplasts of guard cells from isolated epidermis of Argenteum mutant is described. The response of guard cell protoplasts to light, exogenous KCl, ABA and kinetin were similar to those of stomata in isolated epidermis except that the increase in volume of the protoplasts in response to light was maximal at a lower concentration of KCl (10 mol m^-3) and that protoplasts responded more rapidly to light than stomata in isolated epidermis. The protoplasts did not respond to exogenous kinetin, but when incubated for 1 h in the light and in CO₂-free air on a solution containing 10^-3 mol m^-3 ABA, they decreased in volume by 30%. The advantages of using epidermis from Argenteum mutant for experiments on stomatal movements are discussed.Abbreviations ABA abscisic acid - MES 2-(N-morpholino)ethanesulfonic acid     

中国五种仙茅科植物叶形态及其分类学意义

为澄清仙茅科属间界限不清的分类学问题,该文以中国仙茅科3属5种植物为研究对象,利用显微镜、扫描电镜和石蜡切片技术,观察了其叶形态、叶表皮显微特征和叶解剖特征。结果表明:(1)叶形态有小型平整叶、中型波状叶、大型折扇状叶三种。(2)叶表皮毛状体结构为单细胞单列,可分为长柔毛、糙伏毛和星状柔毛三类。(3)叶表皮细胞有六边形和五边形,气孔为平列型和椭圆形,气孔大小和气扎密度呈反比。(4)叶表皮蜡质纹饰有光滑、颗粒、屑状和壳状四类。(5)叶中脉横切面分为平整型和龙骨型,维管束有圆形和椭圆形,叶表皮厚度与表皮细胞具有正相关性。对5种植物的叶形态和叶解剖特征比较分析认为,一些特征组合有助于理解仙茅科属间的亲缘关系和物种鉴定,支持大叶仙茅属独立于仙茅属。     

中国伞形科矮泽芹属植物叶表皮形态特征的研究

利用光学显微镜、扫描电镜对伞形科矮泽芹属8种植物叶表皮形态进行观察与研究。结果表明:(1)矮泽芹属8种植物上下表皮细胞均为不规则形或规则多边形,垂周壁为近平直状或波状,上表皮细胞长宽比在1.3~2.4之间,下表皮细胞长宽比在1.5~2.5之间;在近轴面,有细叶矮泽芹、聂拉木矮泽芹和绿花矮泽芹3种植物没有气孔器的存在,其余物种气孔密度在20~74个/mm2之间,气孔指数为6.0%~17.7%;在远轴面,所有物种都具有丰富的气孔器,气孔密度为100~183个/mm2,气孔指数为16.1%~23.6%。(2)聚类分析结果显示,矮泽芹、大苞矮泽芹、粗棱矮泽芹为类群Ⅰ,鹤庆矮泽芹为类群Ⅱ,聂拉木矮泽芹、细叶矮泽芹、绿花矮泽芹为类群Ⅲ,松潘矮泽芹则单独聚为类群Ⅳ;聚类分析结果大体上支持形态学分类的结果。(3)叶表皮形态特征对于区分矮泽芹属不同物种具有十分重要的分类学价值。     

A systematic investigation of leaf epidermis in <Emphasis Type="Italic">Camellia</Emphasis> using light microscopy

The characters of mature leaf epidermis of 58 species and 3 varieties belonging to 19 sections, representing all the 4 subgenera: Protocamellia, Camellia, Thea and Metacamellia were investigated under light microscope. The main conclusions are as follows: 1) The shape of the epidermal cells is elliptical, polygonal or irregular and the anticlinal walls are arched, straight or sinuolate, sinuous to sinuate. 2) The stomatal apparatus, consisting of a stoma (a pore plus a pair of guard cells) and 3–4 subsidiary cells, restricted to the abaxial surface of the leaves, were assigned to anisocytic, anisotricytic, isotricytic or tetracytic type. 3) Special structures in leaf epidermis, such as stomatal clusters, aborted stomata, secretory cells, cuticular intrusions and their taxonomic implications were also elucidated.     

Water Stress Induced Changes in Anatomy of Tomato Leaf Epidermes

Anatomical changes of leaf epidermes of tomato plants (Lycopersicon esculentum Mill. cv. INCA 9) submitted to water stress in the preflowering stage were studied. 20 d after germination, plants were subjected to three treatments: 1) 100 % of evapotranspired water was applied every day, 2) from 100 up to 10 % of evapotranspired water was applied every day, and 3) water supply was completely suppressed. Trichome density was similar in apical, middle and basal zones, and adaxial and abaxial leaf surfaces. Stomatal density and length, and epidermal cell length and width had similar values on the same leaf surface, but the values were higher on the abaxial than on the adaxial leaf surface. The water deficit had little effect on number of trichomes, length and width of epidermal cells and length of stomata, and decreased the stomatal density especially on adaxial surface.     

西藏东达山3种嵩草属植物气孔特征沿海拔的变化

嵩草属(Kobresia)植物是藏东南高山草甸的优势种和建群种,对该区畜牧业发展和维持生态系统平衡起着重要作用。选择西藏左贡县东达山为研究地点,从林线开始,海拔每升高约100m设置1个样带直至高山草甸分布边缘,共8个样带,调查各样带中物种的组成及盖度,并依据相对盖度和相对频度计算3种嵩草植物矮生嵩草(K.humilis)、线叶嵩草(K.capillifolia)和大花嵩草(K.macrantha)在群落中的重要值,同时取样观察它们叶片远、近轴面表皮细胞形态,测量气孔长度及保卫细胞宽度,计算气孔密度,探讨嵩草属植物对海拔梯度的适应性。结果表明:(1)3种嵩草属植物叶表皮细胞均呈波浪状,气孔器仅分布于远轴面,近轴面无气孔器分布。(2)3种嵩草属植物气孔密度沿海拔梯度的变化均呈单峰曲线分布格局,且在海拔4 537m样带处达到最大值,并表现为矮生嵩草(777.6个/mm2)线叶嵩草(476.4个/mm2)大花嵩草(414.3个/mm2)。(3)随海拔的增加,矮生嵩草和线叶嵩草气孔长度显著增大(P0.05),而保卫细胞宽度显著减小;但大花嵩草气孔长度随海拔的升高而显著减小,保卫细胞宽度基本保持不变。(4)矮生嵩草和线叶嵩草气孔密度、长度和保卫细胞宽度与海拔梯度均显著相关,气孔特征对海拔梯度变化的敏感程度高,与其在群落中重要值高的分布特征一致;而大花嵩草仅气孔密度和长度与海拔梯度显著相关,气孔特征对海拔梯度变化的敏感性低,与其在群落中重要值低的分布特征一致;嵩草属植物气孔密度、长度和保护细胞宽度与海拔梯度之间的相关性,反映出它们在海拔梯度上对生境的适应程度。可见,3种嵩草属植物气孔特征对海拔梯度上生境变化的适应性不同,从而影响它们在群落中的分布范围和物种优势度,其中矮生嵩草和线叶嵩草对环境变化敏感,而大花嵩草对环境变化相对不敏感;保卫细胞宽度与气孔长度同样对植物适应环境变化起重要作用。     

葛(豆科)叶的解剖学研究

利用光学显微镜和扫描电镜观察了葛(Pueraria lobata)叶的解剖学特征。结果表明,葛叶片的上、下表皮都只有一层表皮细胞,上表皮比下表皮厚。上、下表皮都有腺毛和非腺毛。气孔主要分布在下表皮,下表皮的气孔密度为(261±17)mm-2,上表皮只有(6±3)mm-2。叶肉由两层栅栏组织细胞和一层海绵组织细胞构成。叶肉细胞中有丰富的叶绿体。在栅栏组织和海绵组织之间有一层平行于叶脉的薄壁细胞。叶脉中含有大量的草酸钙晶体。葛叶的这些形态特征与其喜阳、耐旱的特点相适应。