Effects of oil on internal gas transport, radial oxygen loss, gas films and bud growth in Phragmites australis

Background and Aims

Oil pollution of wetlands is a world-wide problem but, to date, research has concentrated on its influences on salt marsh rather than freshwater plant communities. The effects of water-borne light oils (liquid paraffin and diesel) were investigated on the fresh/brackish wetland species Phragmites australis in terms of routes of oil infiltration, internal gas transport, radial O₂ loss (ROL), underwater gas films and bud growth.

Methods

Pressure flow resistances of pith cavities of nodes and aerenchyma of leaf sheaths, with or without previous exposure to oil, were recorded from flow rates under applied pressure. Convective flows were measured from living excised culms with oiled and non-oiled nodes and leaf sheaths. The effect of oil around culm basal nodes on ROL from rhizome and root apices was measured polarographically. Surface gas films on submerged shoots with and without oil treatment were recorded photographically. Growth and emergence of buds through water with and without an oil film were measured.

Key Results

Internodes are virtually impermeable, but nodes of senesced and living culms are permeable to oils which can block pith cavity diaphragms, preventing flows at applied pressures of 1 kPa, natural convective transport to the rhizome, and greatly decreasing ROL to phyllospheres and rhizospheres. Oil infiltrating or covering living leaf sheaths prevents humidity-induced convection. Oil displaces surface gas films from laminae and leaf sheaths. Buds emerge only a few centimetres through oil and die.

Conclusions

Oil infiltrates the gas space system via nodal and leaf sheath stomata, reducing O₂ diffusion and convective flows into the rhizome system and decreasing oxygenation of phyllospheres and rhizospheres; underwater gas exchange via gas films will be impeded. Plants can be weakened by oil-induced failure of emerging buds. Plants will be most at risk during the growing season.Key words: Phragmites australis, oil pollution, convective flow, pressure flow resistance, phyllosphere oxygenation, rhizosphere oxygenation, underwater gas films, bud emergence, stomata, pith cavity diaphragms, leaf sheath aerenchyma, rhizome aeration     

A modelling approach to the analysis of pressure-flow in Phragmites stands

Field studies have shown that resistance to convective gas-flow within the culm-rhizome gas-space system of Phragmites tends to be higher in ‘die-back’ as opposed to healthy stands. However, the collection of reliable data and its interpretation is complicated by many factors. To help interpret field measurements and further our understanding of convective flows in general, we have developed mathematical models based on the humidity-induced convective-flow generating potential of culms. Among other things, these make it possible to study the effects on pressure flows of increasing flow resistances in rhizomes and between culms, of different pressure-generating potentials of interlinked culms and of different numbers of efflux culms. A multi-culm and rhizome model is described together with some simple examples of the way it can prove helpful in interpreting some of the field observations from healthy and die-back sites.Increased venting resistance reduced flows curvilinearly; increasing the counter pressure to mimic those induced by other interlinked living culms reduced flows linearly. In some of the multi-culm examples shown counter-pressure exerted an effect approximately the same as that of rhizome and venting resistance, but as culm numbers declined it assumed even greater importance. The value of conductivity derived from applying pressures to the stubble of excised culms and measuring the flows induced, proved to be a composite measure of the effective conductivity of the whole rhizome-culm train rather than that of the rhizome plus major vent. The expression 1−(P_d/P_s) — the delivery coefficient — where P_d is the dynamic pressure in the base of the intact culm, and P_s the static pressure developed by the culm with the outflow blocked, was identified as a useful and easily obtained measure of the ability of an individual intact culm to contribute to the convective gas-flow in a stand, and one which should be relatively unaffected by weather conditions. For identical interlinked culms it was shown that the flows from all culms fitted exactly along the same line of declining flow versus dynamic pressure irrespective of the numbers of culms or number and position of outflow vents.     

The Mechanical Significance of Clasping Leaf Sheaths in Grasses: Evidence from Two Cultivars of Avena sativa

The elastic (Young's) modulus and flexural rigidity of internodeswith and without their clasping leaf sheaths were determinedfor culms from two cultivars (‘Astro’) and (‘Garry’)of Avena sativa L. Data indicate that early in the developmentof culms, leaf sheaths can have a higher elastic modulus thanthe internodes they envelope, and by virtue of their location,leaf sheaths contribute significantly to the flexural rigidity(hence, resistance to bending) of internodal segments. As culmsmature, the elastic modulus of leaf sheath and internodal tissuesreach parity. However, because of the acropetal pattern by whichnew internodes are produced by shoot apices, sheaths continueto provide mechanical support to distal internodes, particularlythe peduncle. Data for the two cultivars indicate that the elasticmodulus and flexural rigidity of culms can vary significantlywithin the species. Comparisons between the flexural rigidityof the two cultures and the resistance of stems to lodging indicatethat flexural rigidity is not significant to lodging. The engineeringprinciples relevant to the mechanical advantages conferred byclasping leaf sheaths are discussed within the context of grassshoot morphology. Biomechanics, leaf sheath, Avena, elastic modulus     

贵州西部箭竹属一新种

报道了贵州西部竹亚科箭竹属一新种,它被命名为威宁箭竹（Fargesia weiningensis Yi et L.Yang）。这个新种近似秦岭箭竹（F.qinlingensis Yi et J.X.Shao,但秆高达6 m,髓呈锯屑状;秆芽仅边缘具短纤毛;枝条较粗,直径达3 mm;箨鞘背面刺毛较密,小横脉不发育,箨舌繸毛长达1.5 cm,箨片常内卷,全部外翻;叶鞘纵脉间无小横脉,上部纵脊明显,叶片较大,长达15.5 cm,宽达1.5 cm,易于区别。     

Dynamics of light and nitrogen distribution during grain filling within wheat canopy

In monocarpic species, during the reproductive stage the growing grains represent a strong sink for nitrogen (N) and trigger N remobilization from the vegetative organs, which decreases canopy photosynthesis and accelerates leaf senescence. The spatiotemporal distribution of N in a reproductive canopy has not been described in detail. Here, we investigated the role of the local light environment on the spatiotemporal distribution of leaf lamina N mass per unit leaf area (SLN) during grain filling of field-grown wheat (Triticum aestivum). In addition, in order to provide some insight into the coordination of N depletion between the different vegetative organs, N dynamics were studied for individual leaf laminae, leaf sheaths, internodes, and chaff of the top fertile culms. At the canopy scale, SLN distribution paralleled the light gradient below the flag leaf collar until almost the end of grain filling. On the contrary, the significant light gradient along the flag leaf lamina was not associated with a SLN gradient. Within the top fertile culms, the time course of total (alive + necrotic tissues) N concentration of the different laminae and sheaths displayed a similar pattern. Another common pattern was observed for internodes and chaff. During the period of no root N uptake, N depletion of individual laminae and sheaths followed a first-order kinetics independent of leaf age, genotype, or N nutrition. The results presented here show that during grain filling, N dynamics are integrated at the culm scale and strongly depend on the local light conditions determined by the canopy structure.     

Field measurements of internal pressurization in Phragmites australis (Poaceae) and implications for regulation of methane emissions in a midlatitude prairie wetland

Emergent aquatic macrophytes in vegetated wetlands provide routes for methane (CH(4)) transport from sites of production in oxygen-poor sediments, where CH(4) concentrations are relatively high, to the atmosphere, which typically has much lower CH(4) concentrations. Transport can occur through aerenchymatous tissue via simple diffusion. Recently, the importance of convective throughflow (i.e., mass transport of gases through plants driven by pressure gradients) in enhancing gas transport has been demonstrated in several genera (e.g., Nuphar, Nymphaea, Nelumbo, Typha, and Phragmites). This study was conducted to elucidate the governing plant-mediated gas transport mechanisms in a midlatitude prairie wetland and to determine both their diel and seasonal variations and the importance of environmental controlling factors. Pressures inside culms of the two dominant emergent aquatic macrophytes (Scirpus acutus and Phragmites australis) were measured directly throughout the growing season and on selected days in midseason. Supporting measurements included solar radiation, air temperature, relative humidity, and windspeed. Results indicated pressures inside green healthy culms of Phragmites were above atmospheric pressure by up to 1650 Pa during the day. At night culm pressures were at or slightly above atmospheric. No pressurization was detected in Scirpus. Highest pressures in Phragmites occurred during midseason when biomass and foliage area index were at their maxima (920 g/m(2) and 2.8, respectively). High internal pressures also coincided with periods of high solar radiation (>500 W/m(2)), high temperature (>20°C), and low relative humidity (<60%). Periods of high internal pressures also coincided with periods of high CH(4) efflux from the wetland as measured in concomitant studies. Convective throughflow driven by internal pressure gradients in Phragmites thus explains much of the diel variation in methane efflux previously reported from this wetland.     

Opaline Silica Deposition in Rye (Secale cereale L.)

The types of opaline silica-bodies (opal phytoliths) which occurin the mature prophylls, radical and culm leaves, culms, andinflorescence bracts of rye (Secale cereale L.) are describedand figured. Silica-bodies are absent from the coleoptile, andthe adaxial epidermis of the prophylls, leaf sheaths, and inflorescencebracts. The stages of silica-body formation in young radicalleaf sheaths are also described. Alternative hypotheses forthe origin of silica-bodies are discussed.     

国产嵩草属(莎草科)植物秆的解剖学研究

对嵩草属27种(亚种)植物秆的解剖学研究证明,嵩草属植物秆的解剖学性状具有系统学意义.在该属中,秆的横切面外形为三角形、圆三角形、圆形或扁圆形.在横切面上分为2个区域;外部区域包括绿色组织、外韧维管束和气腔,内部区域为薄壁组织或其碎裂形成空腔.秆表皮的横切面观和表面观均与叶的下表皮相似.以上特征与莎草科其它类群植物秆的解剖特征一致,不支持将嵩草属和其近缘属另立为嵩草科.同时,秆的解剖学特征可以做为某些在外部形态上难于区分的种之间的分类依据.     

Chimonocalamus bidoupensis,a new temperate bamboo species (Poaceae: Bambusoideae) from Bidoup National Park,southern Vietnam

A new temperate wood bamboo endemic to Vietnam is described and illustrated as Chimonocalamus bidoupensis N.H.Nghia & V.T.Tran. The new species is similar to C. baviensis in general appearance, but differs by its densely ciliate culms, culm sheaths that are concave at the apex with dense, white hairs on the abaxial surface of the sheath, and perfect florets 7–8 mm long.     

The influence of secondary senescence processes within the culm of a pseudoviviparous grass (Poa alpina var. vivipara L.) on the supply of water to propagules

An anatomical investigation of the culm of pseudoviviparous alpine meadow grass (Poa alpina var. vivipara L.) revealed that transpiration flow, as delimited by Lucifer Yellow tracer dye, was maintained despite advanced senescence (as evidenced by loss of chlorophyll and chloroplasts), with leafy spikelets driving transpiration flow. Transpiration flow was not hindered by cavitation or tylosis in older culms, the low frequencies of these senescence processes being bypassed via nodal plexi. Despite this, water content of plantlets declined over time and water stress became apparent, suggesting that water supply via the determinate culm was not sufficient for the increasing transpirational demand of indeterminate plantlets. The implications of declining water content on the biomechanical properties of the culm, and concomitant limitations on the pseudoviviparous reproductive strategy, are discussed. Nomenclature of grass follows Hubbard.     

Implications of missing efflux sites on convective ventilation and amino acid metabolism in Phragmites australis

Three stands of Phragmites australis (Cav.) Trin. ex Steudel were investigated regarding the relationship between the number of efflux culms and convective ventilation efficiency affecting the hypoxic status of roots and rhizomes. The lack of old (efflux) culms after mowing the preceding winter caused a significantly higher counterpressure within the rhizome, thereby diminishing air flushing rate, i.e. oxygen supply, of rhizomes. The levels of alanine and c-aminobutyric acid in basal culm internodes increased significantly. Both amino acids indicate the hypoxic status of the root and rhizome metabolism of P. australis . Amino acid patterns of the basal culm internodes are discussed with respect to the maintenance of aerobic root metabolism and nutrient availability.     

Biology of the bamboo Chusquea culeou (Poaceae: Bambusoideae) in southern Argentina

Over a period of 7 years the biology and phenotypic variability of Chusquea culeou were studied at 5 locations in cool temperate forests of southern Argentina. Excavated rhizomes had an average of 1.1 successful rhizome buds, and an average of 2.1 years elapsed between successive generations of rhizomes. Rhizome buds usually develop within the first four years after a rhizome forms. Height, volume and weight of a culm can be calculated from its diameter 1 m above the ground. Culm size, length of foliage leaf blades, and pattern of secondary branching differed among study sites. Dead culms were numerous and commonly remained erect for more than 7 years after dying. New culm shoots appear in spring and reach full size within a few months. Shoots can grow more than 9 cm/day. Less than half of the shoots survived a year; most were killed by moth larvae. Multiple primary branch buds emerge through the culm leaf sheaths in the second spring. The mean number of branch buds at mid-culm nodes varied between 34.8 and 81.5, and the mean number of primary branches was between 22.8 and 40.8. Number and length of branches, and number and length of foliage leaf blades at each node is related to the position of the node on a culm. Most branches grow about 3 cm and produce 1 to 3 foliage leaves annually. Foliage leaf blades generally live 2 years or more; few survive 6 years. Relative lengths of foliage leaf blades and their spacing along a branch permit recognition of annual cohorts.Both gregarious and sporadic flowering have been reported, and every year a few isolated plants flower and die. Length of the life cycle is unknown. Seedlings require up to 15 years to produce culms of mature size. Foliage branches may live more than 23 years, and culms may survive 33 years. Extensive loss of new shoots to predation suggests that gregarious flowering may be driven by a need to escape parasitism. C. culeou clumps expand slowly. Average annual rate of increase of the number of live culms in a clump was 4.6%. Methods of seed dispersal are undocumented. A dense stand of Chusquea culeou had an estimated phytomass of 179 tons/hectare (dry weight), 28% of which was underground. Net annual production was about 16 t/ha dry weight.     

Leaf contents differ depending on the position in a rice leaf sheath during sink-source transition.

Carbohydrate contents varied with position in a leaf sheath, and differed between the flag leaf sheath and the second leaf sheath below the flag leaf (-2 leaf sheath) in rice (Oryza sativa L.). In the -2 leaf sheath before heading, light microscopy revealed differences in the distribution of starch granules depending on position. Leaf sheaths were divided into several parts, and the contents of carbohydrates (starch, sucrose, and hexoses) were measured in each part. Before heading, the content of accumulated starch increased linearly from the top to the bottom in -2 leaf sheaths (r2=0.99, P<0.001), as did the contents of accumulated sucrose and hexoses in flag leaf sheaths (r2=0.94, P<0.01). In flag leaf sheaths, the relative content of sucrose synthase (SuS), which plays a central role in the degradation of sucrose into hexoses, increased from the top to the bottom, consistent with hexose contents. After heading, the accumulated carbohydrates were dramatically decreased. In -2 leaf sheaths, the activity of alpha-amylase (EC 3.2.1.1), the rate-limiting step in starch degradation, was consistent with the degree of starch degradation, but in flag leaf sheaths with little starch before heading. These results show that carbohydrate contents differ, depending on the position in a leaf sheath. In addition, there were big differences in leaf contents between flag leaf sheaths and -2 leaf sheaths.     

Environmental determinants of Phragmites australis expansion in a New Jersey salt marsh: an experimental approach

Interdependence among disturbance events, ecosystem properties, and biological invasions often make causal relationships difficult to discern. For example, Phragmites australis invasion in mid-Atlantic salt marshes is often associated with disturbances that create well-drained features as well as with low sulfide concentrations, but explanations of these associations have been elusive. We tested experimentally: 1) that disturbances increasing wetland drainage facilitate Phragmites invasion by altering sulfide concentrations and salinity; 2) that translocation allows plants to spread beyond drainage areas; and 3) that plants can then lower edaphic stress through pressure ventilation of the rhizosphere and promote further expansion. At the invasion front, treatments of 1) severing rhizomes to halt translocation and 2) combined severing with clipping dead culms to limit ventilation of the rhizosphere killed most culms, but did not affect pore water chemistry. In already invaded areas, severing and clipping reduced culm height and panicle production, severing alone and in combination with clipping also raised sulfide and ammonium concentrations in the root zone. There were no treatment effects on plant performance or pore water chemistry along mosquito ditches, where sulfide concentrations were negligible. Small-scale hydrological alterations such as ditches appear to provide suitable sites for the establishment of Phragmites because soils are well-drained and are low in free sulfides. Subsequent expansion into more hostile areas occurs through translocation, with well-drained areas acting as sources for essential substances. Once established, the plant increases rhizosphere oxygenation and lowers sulfide concentrations.     

不同水分管理下优质稻花后植株碳氮流转与籽粒生长及品质的相关性

以桂华占、八桂香为材料,在干湿交替灌溉、亏缺灌溉、淹水灌溉3种水分条件下,研究优质稻花后植株碳氮流转与籽粒生长及品质的相关性。结果表明:不同水分管理下,桂华占和八桂香花后碳氮流转与籽粒的生长间存在密切相关。主要表现在:(1)茎鞘和叶片干物质转运对籽粒干物质积累的贡献率为16.86%～25.68%,花后茎叶干物质运转速度和运转率与籽粒起始灌浆势呈显著甚至极显著正相关;籽粒最大灌浆速率、活跃灌浆期、持续灌浆时间与叶片干物质运转速度和运转率呈极显著正相关,与茎鞘干物质运转速度和运转率呈极显著负相关;(2)茎鞘碳同化物转运对籽粒的产量和淀粉产量的贡献率则为干湿交替灌溉>亏缺灌溉>淹水灌溉;但叶片碳同化物转运对籽粒的产量和淀粉产量的贡献率则为淹水灌溉>亏缺灌溉>干湿交替灌溉;茎叶可溶性糖积累量的减少和籽粒直链淀粉含量和积累量增加是同步的,且茎叶可溶性糖积累量快速递减期(花后3～12d)与直链淀粉含量和积累量快速递增期(花后6～12d)同步;(3)茎鞘和叶片氮素转运对籽粒氮素积累的贡献率为44.05%～117.66%,叶片总氮转运对籽粒氮素积累的贡献率大于茎鞘,茎鞘和叶片氮同化物对籽粒氮素的贡献率以淹水灌溉处理的最大,亏缺灌溉处理的次之,干湿交替灌溉处理的最小。     

The Estimated Impact of Fungi on Nutrient Dynamics During Decomposition of Phragmites australis Leaf Sheaths and Stems

Decomposition of culms (sheaths and stems) of the emergent macrophyte Phragmites australis (common reed) was followed for 16 months in the litter layer of a brackish tidal marsh along the river Scheldt (the Netherlands). Stems and leaf sheaths were separately analyzed for mass loss, litter-associated fungal biomass (ergosterol), nutrient (N and P), and cell wall polymer concentrations (cellulose and lignin). The role of fungal biomass in litter nutrient dynamics was evaluated by estimating nutrient incorporation within the living fungal mass. After 1 year of standing stem decay, substantial fungal colonization was found. This corresponded to an overall fungal biomass of 49 ± 8.7 mg g⁻¹ dry mass. A vertical pattern of fungal colonization on stems in the canopy is suggested. The litter bag experiment showed that mass loss of stems was negligible during the first 6 months, whereas leaf sheaths lost almost 50% of their initial mass during that time. Exponential breakdown rates were −0.0039 ± 0.0004 and −0.0026 ± 0.0003 day⁻¹ for leaf sheaths and stems, respectively (excluding the initial lag period). In contrast to the stem tissue—which had no fungal colonization—leaf sheaths were heavily colonized by fungi (93 ± 10 mg fungal biomass g⁻¹ dry mass) prior to placement in the litter layer. Once being on the sediment surface, 30% of leaf sheath's associated fungal biomass was lost, but ergosterol concentrations recovered the following months. In the stems, fungal biomass increased steadily after an initial lag period to reach a maximal biomass of about 120 mg fungal biomass g⁻¹ dry mass for both plant parts at the end of the experiment. Fungal colonizers are considered to contain an important fraction of nutrients within the decaying plant matter. Fungal N incorporation was estimated to be 64 ± 13 and 102 ± 15% of total available N pool during decomposition for leaf sheaths and stems, respectively. Fungal P incorporation was estimated to be 37 ± 9 and 52 ± 15% of total available P during decomposition for leaf sheaths and stems, respectively. Furthermore, within the stem tissue, fungi are suggested to be active immobilizers of nutrients from the external environment because fungi were often estimated to contain more than 100% of the original nutrient stock.     

竹亚科刚竹属植物的修订(Ⅳ)——Phyllostachys hispida的恢复及其近缘种的分类

在模式标本考证、居群调查和引种栽培的基础上,确认毛壳竹(Phyllostachys hispida S.C.Li,S.H.Wu et S.Y.Chen)与乌竹(P.varioauriculata S.C.Li et S.H.Wu)在新秆性状、秆箨颜色、箨舌高度及颜色、叶鞘毛被上有较大的区别,应作为独立的竹种看待。小叶光壳竹(P.varioauriculata var.glabrata G.H.Lai)也因新秆下部一段呈扁圆形、秆箨基部具长柔毛,叶片很小等特征而明显不同于乌竹,应提升为一个独立的竹种,但由于存在晚出同名问题而给出新名称P.microphylla G.H.Lai。同时还描述了毛壳竹的一新变种,即光壳竹(P.hispida var.glabrivagina G.H.Lai)。日本所产的姬淡竹与毛壳竹属于同一种系,因其学名P.humilis Muroi为一裸名,应予废弃。     

Pattern and Amount of Aerenchyma Relate to Variable Methane Transport Capacity of Different Rice Cultivars

Abstract: Aerenchyma, developed in both root and aboveground parts of rice plants, is predominantly responsible for plant‐mediated transfer of methane (CH₄) from the soil to the atmosphere. To clarify the pathways of CH₄ transport through the rice plant and find differences that may determine the large¡variation in the patterns of methane transport capacity (MTC) of rice cultivars, we examined the appearance, the distribution pattern, and the density of aerenchyma in different parts of rice¡plants of three widely varying rice cultivars during panicle initiation, flowering, and maturity stages. The data on the amount and density of small (> 1 ¡Á 10³? 5 ¡Á 10³Ìm²), medium (> 5 ¡Á 10³? 20 ¡Á 10³Ìm²) and large aerenchyma lacunae (> 20 ¡Á 10³Ìm²) were collected using a computer assisted image‐analyzing system. The brightfield optical microscopy of roots of all tested rice plants demonstrated the continuity of aerenchyma channels in the roots that function as conduits for bi‐directional transport of gases. The aerenchyma channels of primary roots showed direct connection with those of culms. Intercalary meristems were found at the transition zone of rootaCculm aerenchyma connections. Well‐developed aerenchyma lacunae present in the internodal region of the culm base were uniformly distributed in the peripheral cortical zone. The nodal region had relatively fewer and smaller aerenchyma lacunae that showed a non‐uniform distribution pattern. As a result, few aerenchyma channels continued from the internodal region through to the nodal region. The aerenchyma in the cortex zone of the culm expanded along with the growing secondary tiller, developing continuity between the culm and the secondary tiller. The micrographs of longitudinal sections of different specimens of culmaCleaf sheath intersection showed the continuity of aerenchyma channels from the culm to the leaf. The amount of medium and large aerenchyma lacunae in the leaf sheath was respectively 2 and 33 times greater as compared to those of the tiller. The proportion of the large lacunae in the total amount of aerenchyma in leaf sheath was 75 % as compared to only 8 % in the tiller, revealing higher number and larger size of aerenchyma in the former. There were significant differences in amount and density of aerenchyma between individual cultivars at a given growth stage, as well as in the development patterns. While the amount and density of medium and small aerenchyma lacunae in the internodal region of the culm base did not show any relationship with MTC of rice cultivars, large aerenchyma lacunae exhibited highly significant correlations with MTC of different cultivars, suggesting that the wide variation in MTC of rice plants during different growth stages are related to these structural features.     

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。