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White spot syndrome virus (WSSV) is a serious pathogen threatening global crustacean aquaculture with no commercially available drugs. Herbal medicines widely used in antiviral research offer a rich reserve for drug discovery. Here, we investigated the inhibitory activity of 13 herbal medicines against WSSV in crayfish Procambarus clarkii and discovered that naringenin (NAR) has potent anti-WSSV activity. In the preliminary screening, the extracts of Typha angustifolia displayed the highest inhibitory activity on WSSV replication (84.62%, 100 mg/kg). Further, NAR, the main active compound of T. angustifolia, showed a much higher inhibition rate (92.85%, 50 mg/kg). NAR repressed WSSV proliferation followed a dose-dependent manner and significantly improved the survival of WSSV-challenged crayfish. Moreover, pre- or post-treatment of NAR displayed a comparable inhibition on the viral loads. NAR decreased the transcriptional levels of vital genes in viral life cycle, particularly for the immediately early-stage gene ie1. Further results showed that NAR could decrease the STAT gene expression to block ie1 transcription. Besides, NAR modulated immune-related gene Hsp70, antioxidant (cMnSOD, mMnSOD, CAT, GST), anti-inflammatory (COX-1, COX-2) and pro-apoptosis-related factors (Bax and BI-1) to inhibit WSSV replication. Overall, these results suggest that NAR may have the potential to be developed as preventive or therapeutic agent against WSSV.

Background Tomato/potato psyllid (TPP), Bactericera cockerelli (Sulc), is a recently established invasive pest of solanaceous crops in New Zealand. No alternative control strategies are available against TPP due to the development of insecticidal resistance. We investigated the combined use of the predatory mites Amblydromalus limonicus or Neoseiulus cucumeris with either the fungus Beauveria bassiana (suspensions and dry conidia) or with Typha orientalis pollen as a control of TPP in greenhouse bell pepper over 7 weeks. Results All treatments significantly reduced TPP densities compared with the control. A. limonicus resulted in significantly lower TPP densities than any other combination with N. cucumeris. B. bassiana suspensions did not affect A. limonicus densities when they were combined. However, the application of dry B. bassiana conidia significantly reduced the densities of A. limonicus. The use of T. orientalis pollen resulted in significantly higher densities of A. limonicus but densities of N. cucumeris did not increase. The combined use of A. limonicus with B. bassiana suspensions or T. orientalis pollen resulted in significantly decreased TPP populations and greater crop yield. Conclusion The synergistic application of A. limonicus with B. bassiana suspensions could be a suitable strategy to control TPP in the greenhouse. © 2019 Society of Chemical Industry.

With the projected increase in drought duration and intensity in future, small water bodies, and especially the terrestrial-aquatic interfaces, will be subjected to longer dry periods with desiccation of the sediment. Drought effects on the plant-sediment microorganism carbon continuum may disrupt the tight linkage between plants and microbes which governs sediment carbon and nutrient cycling, thus having a potential negative impact on carbon sequestration of small freshwater ecosystems. However, research on drought effects on the plant-sediment carbon transfer in aquatic ecosystems is scarce. We therefore exposed two emergent aquatic macrophytes, Phragmites australis and Typha latifolia, to a month-long summer drought in a mesocosm experiment. We followed the fate of carbon from leaves to sediment microbial communities with 13 CO2 pulse labelling and microbial phospholipid-derived fatty acid (PLFA) analysis. We found that drought reduced the total amount of carbon allocated to stem tissues but did not delay the transport. We also observed an increase in accumulation of 13 C-labelled sugars in roots and found a reduced incorporation of 13 C into the PLFAs of sediment microorganisms. Drought induced a switch in plant carbon allocation priorities, where stems received less new assimilates leading to reduced starch reserves whilst roots were prioritised with new assimilates, suggesting their use for osmoregulation. There were indications that the reduced carbon transfer from roots to microorganisms was due to the reduction of microbial activity via direct drought effects rather than to a decrease in root exudation or exudate availability.

The effect of phosphorous enrichment on decomposition rate, exoenzymatic activities (β-glucosidase, cellobiohydrolase and alkaline phosphatase), and macroinvertebrate abundance in Typha latifolia leaves were assessed in a 2nd order Pampean stream (Central Argentina). Phosphorous was added to a downstream reach while another reach located upstream was kept intact and, once significant differences in phosphorus concentration in water were attained, leaf bags were attached to each reach bottom. T. latifolia leaves lost 77% of their initial weight along 154 days and decomposition rates were not significantly different between reaches. Besides, neither exoenzymatic activities nor macroinvertebrate abundances differed between reaches. However, an increment in leaf phosphorus content, attributed to immobilization by decomposer microorganisms, was detected in the enriched reach.

Fipronil, a phenyl-pyrazole insecticide, is often used in rice (Oryza sativa L.) production agriculture, with elevated runoff concentrations and loads having potential toxicological effects on downstream aquatic environments. This study evaluated two species of aquatic plants-broadleaf cattail (Typha latifolia L.) and powdery alligator-flag (Thalia dealbata Fraser ex Roscoe)-placed in series against a nonvegetated mesocosm in reducing concentrations and loads of fipronil, and associated metabolites. Vegetation type and hydrological condition (inundated vs. dry) were treatment effects used for comparison. The vegetated mesocosms significantly reduced higher loads and concentrations of fipronil, fipronil sulfone, and sulfide in both inundated and dry hydrological conditions over nonvegetated nesocosms. Under inundation conditions, vegetated mesocosms reduced >50% of influent fipronil concentrations and betweeen 60 and 70% of fipronil loads, which was significantly higher than the dry conditions (10-32% concentration and load). These results show that agricultural management strategies usingephemeral aquatic zones, such as drainage ditches, can be optimized to couple chemical applications with vegetation presence and hydrology to facilitate the reduction in chemical waste loads entering downstream aquatic ecosystems. Such reduction is critical for use with fipronil, where negative impacts have been demonstrated with several nontarget species.

12 páginas, 6 figuras, 1 tabla., Pollen analyses of 12 Iranian species of Typha L. were conducted through light microscopy and scanning electron microscopy. Among the twelve studied species, we found that five species, T. caspica, T. latifolia, T. lugdunensis, T. minima and T. shuttleworthii, present pollen in tetrads, whereas the remaining seven species, T. angustifolia, T. azerbaijanensis, T. domingensis, T. grossheimii, T. kalatensis, T. laxmanii and T. tourcomanica, have pollen in monads. The exine of Typha species is mostly reticulate although a few species present perforate-microreticulate and rugulate exine. Our analyses revealed that using a combination of light microscopy and scanning eletron microscopy characters the identification of species is feasible. A diagnostic key based on palynological traits is presented for all studied taxa., We thank Dr. A. A. Maas soumi for providing herbarium vouchers from TARI and for useful comments in an earlier version of this manuscript. M. Moussavi and F. Aghbeigi for providing facilities to study IRAN specimens. M. Rahmani for assistance with SEM analysis. The study on the family Typhaceae in IRAN was partially supported by Project 105 of the Islamic Azad University, Garmsar branch, Research Council to SMM Hamdi. J. G. Segarra-Moragues was supported by an ARAID (Agencia Aragonesa para la Investigación y el Desarrollo) postdoctoral contract.

Summary 1. By increasing vigour and broadening ecological tolerances, hybridization between native and introduced species may serve as a primary driver of invasiveness. 2. Cattails (Typha, Typhaceae) are clonal wetland graminoids that are known to hybridize where anthropogenic influences have resulted in distributional overlap. 3. In order to gauge the relative performance of hybrid vs. pure Typha, we characterized hybridization and clonal growth where native Typha latifolia and introduced Typha angustifolia occur together in the Western Great Lakes Region of North America. 4. Based on microsatellite markers, we documented F1 hybrids as the most common class at five intensively sampled sites, constituting up to 90% of the genets and 99% of the ramets. Backcrosses to one or the other parent constituted 5–38% of the genets. Pure T. latifolia was rare and never constituted more than 12% of the genets. 5. F1 hybrid genets achieved the highest mean ramet numbers at three sites, and were second in size only to T. angustifolia at two sites; however, these differences were not significant based on site-specific one-way anovas. 6. F1 hybrids exhibited little height advantage over other Typha classes, although there was a general tendency for hybrids in relatively mixed stands to be among the tallest genets in shallow water, but among the shortest genets in deeper water. 7. Native T. latifolia was found growing at the shallowest water depths at the only site where it was sufficiently abundant to be included in statistical comparisons. 8. Synthesis. The role of hybridization in plant invasions can be difficult to confirm in the absence of molecular data, particularly for clonal species where the boundaries separating individuals are otherwise difficult to discern. Here, we used molecular markers to document the prevalence and performance of hybrid genets in five invasive Typha stands covering a broad area of the Western Great Lakes Region. We found an extremely high prevalence of F1 hybrids within mixed Typha stands. This, coupled with the typically larger sizes of hybrid genets, suggests that hybrids are capable of outperforming other Typha spp. and that hybridization has played an influential role in the North American cattail invasion.

Typha latifolia, commonly known as cattail, is widely used as traditional food and medicinal ingredients by indigenous people. There have been concerns over the high levels of total arsenic in cattail plants, but the chemical species of arsenic in cattail have not been characterized. We describe here the determination of arsenic species in the various compartments of cattail. Average concentrations of total arsenic from 9 to 19 cattail plants were 1120 microg/kg (range 68-2600 microg/kg) in the fine (hairy) roots, 575 microg/kg (range 16-1400) in the skin of tuber, 26 microg/kg (range 2-82) in the core of the tuber, 6 microg/kg (range 5-12) in the stem, and 420 microg/kg (range 4-1970) in the whole tuber. Speciation analysis using strong anion exchange, ion pairing, and strong cation exchange chromatography separation with MS detection revealed the presence of inorganic arsenite, arsenate, dimethylarsinic acid, and monomethylarsonic acid. The two inorganic arsenic species accounted for >80% of the total arsenic. Further analyses of arsenic and iron concentrations showed a strong correlation between arsenic and iron in the fine roots and skin. These results suggest that arsenic and iron are colocalized (codeposited) in the skin of the cattail plants, consistent with the previous findings. The level of exposure to arsenic from the use of cattail as food and medicine can be substantially reduced by removing the skin of cattail.

Invaded systems are commonly associated with a change in ecosystem processes and a decline in native species diversity; however, many different causal pathways linking invasion, ecosystem change, and native species decline could produce this pattern. The initial driver of environmental change may be anthropogenic, or it may be the invader itself; and the mechanism behind native species decline may be the human-induced environmental change, competition from the invader, or invader-induced environmental change (non-trophic effects). We examined applicability of each of these alternate pathways in Great Lakes coastal marshes invaded by hybrid cattail (Typha x glauca). In a survey including transects in three marshes, we found that T. x glauca was associated with locally high soil nutrients, low light, and large amounts of litter, and that native diversity was highest in areas of shallow litter depth. We tested whether live T. x glauca plants or their litter induced changes in the environment and in diversity with a live plant and litter transplant experiment. After one year, Typha litter increased soil NH4+ and N mineralization twofold, lowered light levels, and decreased the abundance and diversity of native plants, while live Typha plants had no effect on the environment or on native plants. This suggests that T. x glauca, through its litter production, can cause the changes in ecosystem processes that we commonly attribute to anthropogenic nutrient loading and that T. x glauca does not displace native species through competition for resources, but rather affects them non-trophically through its litter. Moreover, because T. x glauca plants were taller when grown with their own litter, we suggest that this invader may produce positive feedbacks and change the environment in ways that benefit itself and may promote its own invasion.

Healthy growth of plants is a prerequisite for successful application of phytoremediation technologies. Typha angustifolia and Phragmites communis are common wetland plants and have shown potential for phytoremediation of hexachlorobenzene (HCB). However, the lack of phytotoxicity data impedes their application in field sites. This study investigated the phytotoxicity of HCB, and its two metabolites: 1,3,5-trichlorobenzene (1,3,5-TCB) and 1,4-dichlorobenzene (1,4-DCB) to Typha and the phytotoxicity of 1,3,5-TCB to Phragmites. The phytotoxicity of 1,3,5-TCB is species-dependent, with Typha demonstrating significantly higher tolerance than Phragmites. The concentration of 1,3,5-TCB causing zero growth of Phragmites was determined to be 1575 mg TCB/kg dry sediment. The concentration has to be doubled to completely inhibit the growth of Typha. Adverse effects of chlorinated benzenes in sediments on Typha increased with decreasing chlorine atoms. The concentrations causing zero growth of Typha are 5765 mg HCB/kg dry soil, 3157 mg 1,3,5-TCB/kg dry soil, and 1325 mg 1,4-DCB/kg dry soil. The higher toxicity of 1,4-DCB than 1,3,5-TCB and HCB in sediment was ascribed to its higher availability and easiness to be taken up by plants. The conclusion was supported by both growth rate calculations and plant height measurements. (c) 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.

Summary 1. Water velocity plays an important role in shaping plant community structure in flowing waters although few authors have yet attempted to explain the adaptation of plants to flow. 2. We aimed to test two hypotheses, that: (i) some emergent macrophytes reconfigure their shoot distribution in fast currents and form clumps, and (ii) the shape and morphology of such clumps minimises drag caused by the current. The study focuses on three emergent macrophytes that co-occur along a gradient of water velocity. 3. The species showed a clear zonation in response to water depth and current velocity. Phragmites australis occupied shallower and more slowly flowing water than Typha angustifolia and Zizania latifolia, which had similar preferences. 4. Both T. angustifolia and Z. latifolia shoots were more clumped at high velocity, whereas they were more randomly distributed at low flow or in stagnant water. Because of the low shoot density, water flowed more easily through T. angustifolia clumps, whereas Z. latifolia clumps had a high shoot density and large amounts of trapped litter, causing stagnant water in the centre of the clump. The clumps of Z. latifolia with a high density of shoots were longer and narrower than T. angustifolia clumps. Phragmites australis was less tolerant of flow than the other two species and large amounts of litter trapped in the clumps impaired flow. 5. The shoot distribution of both T. angustifolia and Z. latifolia is reconfigured at high flow and this minimises drag on the clumps.

Summary • This study explored patterns of nutrient resorption in wetland macrophytes to test the prediction that plants from regions with a strong nutrient limitation will show higher resorption of the limiting nutrient. • Nitrogen and phosphorus resorption was assessed in macrophytes from marshes of different nutrient status in tropical and temperate regions, and expressed as resorption efficiency (NRE, PRE) and proficiency (NRP, PRP). Macrophytes were grouped into three categories: Typha, graminoids and broadleaved plants. • Nitrogen was less limiting than P, consequently N availability varied less than P availability, NRP and NRE were lower, and N resorption was mostly incomplete. NRP was determined more by growth form than by local conditions. The large range of soil P concentrations allowed an exploration of relationships between P availability and resorption along a wide gradient. P-limited macrophytes (N : P > 16) had significantly higher PRP and PRE. Resorption proficiency was found to be a more sensitive indicator of changes in nutrient availability than resorption efficiency. • The results confirmed that resorption in wetland macrophytes depends on nutrient availability, and is higher at nutrient-limited sites. A particularly strong relationship was found between resorption indicators and P limitation expressed either as live tissue N : P or soil P.

Subsurface-flow experimental reed beds were designed and built based on a combination of two design methodologies. Four different growing media were used with a combination of topsoil, gravel, river sand, and mature wastewater biosolids compost to determine the best substrate for chemical oxygen demand removal. Eight units were constructed, two for each material. One bed for each pair was planted with Typha latifolia plants commonly known as cattails. Primary-treated domestic wastewater was continuously fed to the beds for more than 6 months. The best performance was achieved by the gravel reed beds, with an average removal rate higher than 50%. Soil-based beds containing topsoil and sand only managed to attain removals of approximately 10%. The reed beds containing compost in their substrate produced the worst treatment, mainly because of leaching of organic substances from the compost. Primarily as a result of channel flow, all beds showed significant deviation from the designed retention time. There was no significant difference in the performance of planted and unplanted reed beds.

Lead poisoning of waterfowl from direct ingestion of wetland mine tailings has been reported at the Coeur d'Alene River basin in Idaho. A greenhouse study was conducted to evaluate the effects of surface applications of amendments on lead bioavailability in the tailings. Treatments included sediment only, and sediment with three different surface amendments: (i) biosolids compost plus wood ash, (ii) compost + wood ash + a low SO4(2-) addition as K2SO4, and (iii) compost + wood ash + a high SO4(2-) addition. Measured variables included growth and tissue Pb, Zn, and Cd concentration of arrowhead (Sagittaria latifolia Willd.) and cattail (Typha latifolia L.) and soil pH, redox potential (Eh), pore water Pb, Pb speciation by X-ray absorption spectroscopy, and in vitro Pb bioavailability. The compost + ash amendment alleviated phytotoxicity for both plant species. Bioavailability of Pb as measured by a rapid in vitro extract decreased by 24 to 34% (over control) in the tailings directly below the amendment layer in the compost + SO4 treatments. The ratio of acid volatile sulfide (AVS) to simultaneously extracted metals (SEM) also indicated a reduction in Pb bioavailability (1:40 control, 1:20 compost, 1:8 compost + low SO4, and 1:3 compost + high SO4). Extended X-ray adsorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy data indicated that lead sulfide was greater after 99 d in the treatments that included additions of sulfate. These results indicated that, under reducing conditions, surface amendments of compost + wood ash (with or without sulfate) decreased the bioavailability of Pb in metal-contaminated mine tailings.

Article contains the description of two new species of cat-tails (Typha L., Typhaceae Juss.) from Russian Far East and from Mongolia: Typha tzvelevii sp. nova (sect. Typha) and T. joannis sp. nova [sect. Engleria (Leonova) Tzvelev]. The taxonomical position of T. orientalisC.Presl is specified. Es werden zwei neue Arten der Gattung Typha L., Typhaceae Juss., aus dem Fernen Osten Russlands und aus der Mongolei beschrieben: Typha tzelevii sp. nova (Sect. Typha) und T. joannis sp. nova [Sect. Engleria(Leonova) Tzvelev]. Die taxonomische Stellung von T. orientalis C.Presl wird prazisiert.

The objective of this work was to determine whether radial oxygen loss (ROL) from roots of Typha domingensis and Cladium jamaicense creates an internal oxygen deficiency or, conversely, indicates adequate internal aeration and leakage of excess oxygen to the rhizosphere. Methylene blue in agar was used to visualize the pattern of ROL from roots, and oxidation of a titanium-citrate solution was used to quantify rates of oxygen leakage. Typha's roots had a higher porosity than Cladium's and responded to flooding treatment by increasing cortical air space, particularly near the root tips. A greater oxygen release, which occurred along the subapical root axis, and an increase in rhizosphere redox potential (E(h)) over time were associated with the well-developed aerenchyma system in Typha. Typha roots, regardless of oxygen release pattern, showed low or undetectable alcohol dehydrogenase (ADH) activity or ethanol concentrations, indicating that ROL did not cause internal deficiencies. Cladium roots also released oxygen, but this loss primarily occurred at the root tips and was accompanied by increased root ADH activity and ethanol concentrations. These results support the hypothesis that oxygen release by Cladium is accompanied by internal deficiencies of oxygen sufficient to stimulate alcoholic fermentation and helps explain Cladium's lesser flood tolerance in comparison with Typha.

The biodiversity of coal slurry ponds can be inhibited, at least in part, by dense stands of Phragmites australis. In this study, we demonstrate that species richness can be increased in coal slurry ponds if the dominant species (P. australis and Typha latifolia) are removed and that underwater herbivory simulated by cutting will kill emergents. The study was conducted in the greenhouse and the field in both flooded and drawndown conditions. Stems of plants of P. australis and T. latifolia were cut in a greenhouse and the cut plants of both species showed a decline in survivorship (25 and 42% survival, respectively) whereas all uncut plants survived. In a reclaimed coal pond at Pyramid State Park, Illinois, neither P. australis nor T. latifolia survived cutting underwater, but all of the uncut plants survived. Regrowth measured as total biomass of stems was less among flooded versus freely drained plants (0.3 and 2.6 g biomass, respectively). Cut versus uncut plants, combining freely drained and flooded, had less below-ground biomass (99.4 and 254.4 g, respectively). In the greenhouse study, oxygen levels in rhizomes subsequent to cutting were measured using an oxygen electrode and millivolt meter. Oxygen levels in P. australis were lower in cut versus uncut plants both in flooded (15.0 vs. 16.3% ambient O 2 , respectively) and freely drained conditions (14.5 vs. 15.0%, ambient O 2 , respectively). Similar responses to cutting were demonstrated by T. latifolia. In an unreclaimed coal slurry pond with monospecific stands of P. australis, plant species richness increased in cut plots as compared to uncut plots (29 vs. 2 species, respectively) between March and September, 1995. This study demonstrated that species richness can be increased in coal ponds by mechanical cutting and this potentially by herbivory; however, the additional species were mostly exotics.

Long-term studies along a 30-yr nutrient-enrichment gradient in the northern part of the subtropical Everglades fen allowed us to assess the effects of nitrogen (N) and phosphorus (P) additions on plant community structure and chemical qualities of wetland plants. Areas in the highest P-enriched zones (>1000 mgP/kg), once dominated by open-water sloughs and surrounding monocultures of sawgrass (Cladium jamaicense, a stress-tolerant low-nutrient-status species), are now dominated by cattail (Typha domingensis, a competitive, high-nutrient-status species). Areas of moderate (750–500 mg/kg) and low (

We measured the flow of methane in Typha latifolia L. (cattail)-dominated wetlands from microbial production in anoxic sediment into, through, and out of emergent T. latifolia shoots (i.e. plant transport). The purpose was to identify key environmental and plant factors that might affect rates of methane efflux from wetlands to the Earth's atmosphere. Methane accumulated in leafy T. latifolia shoots overnight, reaching concentrations up to 10000 μl l−1 (vs. atmospheric concentrations 2·0 μmol m−2 (leaf) s−1) and (b) a decrease in shoot methane concentration to

summary The effects of iron plaque on the growth of Typha latifolia L. and accumulation of copper and nickel in T. latifolia were investigated under laboratory conditions in nutrient solution cultures. Seedlings with and without iron plaque on their roots were exposed to 0.05 μg ml−1 Cu and 0.10 μg ml−1 Ni solutions for 72 d. The results showed no differences in root and shoot d. wt and leaf elongation when Cu or Ni were added to the solution and in the presence or absence of plaque. However, root length was reduced by Cu and Ni, and the reduction in root length was greater in the presence of plaque. Some Cu and Ni was adsorbed on root surfaces; roots with plaque took up more Cu, but less Ni than those without. The presence of plaque did not alter Cu uptake and translocation but increased Ni uptake and translocation. Most of the Cu and Ni taken up was retained in the roots, suggesting that the root tissue rather than the root surface or plaque is the main barrier for Cu and Ni transport. The results differ from those reported for other species.

Three successive emergent macrophytes (Typha latifolia L., Phragmites australis (Cav.) Steudel and Glyceria maxima (Hartman) Holmbly) were each grown in substrates collected from three different zones of shoreline vegetation development (non- vegetated sediment, the interface between T. latifolia and P. australis, and degenerating P. australis). The aim of the study was to assess whether accumulation of litter changes growth conditions of P. australis, and to determine its effects on pre- and post successional plant species. The study was carried out by means of pot experiments in a glasshouse. Seedlings of the three species were cultured in fertilized and unfertilized substrates under both waterlogged and drained conditions. In its own litter, growth of P. australis was strongly reduced, compared with the productivity of plants in substrates from preceeding successional stages, and could not be compensated for by fertilization or soil drainage. The redox potential of the substrate was not strongly reduced and the sediment density was well above the critical level. Soil sterilization by gamma- irradiation did not improve growth substantially, although there was some positive effect in unfertilized substrate. Phytotoxic compounds might have caused poor growth of P. australis in its own litter. T. latifolia and G. maxima were relatively less affected by the P. australis litter. The possible importance of litter accumulation on species replacement in shoreline vegetation is discussed. It is concluded that the accumulation of organic matter should be considered as a factor affecting spatio-temporal processes in littoral vegetation owing to its specific impact on the functioning of individual dominant plant species. [KEYWORDS: littoral vegetation; succession; phytotoxins; Phragmites australis; anaerobe decomposition Spartina-alterniflora; soil; marsh; vegetation; sediment; plants; roots; reed; decomposition; netherlands]

Base cations (Ca, Mg, K, Na) and metals (Al, Fe, Mn) were measured in peatlands of the northern and central Everglades to (i) determine the extent and degree of elemental enrichment of the peat caused by agricultural drainage and (ii) assess the relationship between cattail (Typha latifolia L.) encroachment into sawgrass (Cladium jamaicense Crantz) communities and elemental (cations, metals, P) enrichment of the peat. Soil Ca, Mg, and Na (0-10 cm) decreased, and Al and Fe increased from north to south through the northern and central Everglades. In particular, nutrient-enriched (P) areas of northern WCA 2A had higher concentrations and accumulation rates of Ca, Mg, and Na than areas to the south. A detailed investigation along a P enrichment gradient in northern WCA 2A revealed a gradient of Ca and Na enrichment extending 1.6 to 3.4 km downstream of the Hillsboro canal, the source of agricultural drainage to WCA 2A. Rates of Ca (35 g/m 2 per yr) and Na (1.5-3.2 g/m 2 per yr) accumulation were 2 to 10 times greater 1.6 km below the Hillsboro canal than in areas 3.4 to 10.7 km downstream. Correlation analysis revealed that macrophyte species composition along the enrichment gradient was highly correlated with soil P (0-24 cm) but not with soil Na or Ca. The percent frequency of cattail (r = 0.74) and other species (r = 0.66) was positively correlated while sawgrass (r = -0.83) was inversely correlated with soil P content. These findings suggest that cattail encroachment into sawgrass communities is favored by enrichment of the peat with P loadings from agricultural drainage pumped into northern WCA 2A.

The effects of solution pH on NH4+ uptake kinetics and net H+ extrusion by Typha latifolia L. were studied during short-term (days) and long-term (weeks) exposure to pH in the range of pH 3.5–8.0. The NH4+ uptake kinetics were estimated from depletion curves using a modified Michaelis-Menten model. T. latifolia was able to grow in solution culture with NH4+ as the sole N source and to withstand a low medium pH for short periods (days). With prolonged exposure (weeks) to pH 3.5, however, the plants showed severe symptoms of stress and stopped growing. The solution pH affected NH4+ uptake kinetics. The affinity for NH4+, as quantified by the half saturation constant (K1/2) and Cmin (the NH4+ concentration at which uptake ceases), decreased with pH. K1/2 was increased from 7.1 to 19.2 mmol m−3 and Cmin from 2.0 to 5.7 mmol m−3 by lowering the pH in steps from 8.0 to 3.5. Vmax was, however, largely unaffected by pH (∼22 μmol h−1 g−1 root dry weight). Under prolonged exposure to constant pH, growth rates were highest at PH 5.0 and 6.5. At pH 8.0 growth was slightly depressed and at pH 3.5 growth completely stopped. NH4+ uptake kinetics were similar at pH 5.0, 6.5 and 8.0 whereas at pH 3.5 NH4+ uptake almost completely stopped. The ratio between net H+ extrusion and NH4+ uptake decreased significantly at low pH. The adverse effects of low pH on NH4+ uptake kinetics are probably a consequence of a reduced H+-ATPase activity and/or an increased re-entry of H+ at low pH, and the associated decrease in the electrochemical gradient across the plasma membranes of the root cells.

Diurnal and seasonal patterns of CO2 concentration ([CO]) in leaf gas spaces were measured to better understand the relationship of sediment-derived CO2 to photosynthesis in the emergent wetland species, Typha latifolia L. (cattail). Leaf [C02] was above 2,000 Al/liter at dawn on all but the first sampling date. At all sampling dates, leaf [CO2] declined to near atmospheric [C02] at midday and rose to well above atmospheric [C02] in the late afternoon. The maximum leaf [C02] varied with sampling date and was over 18 times atmospheric levels (over 6,300 ,ul/liter) in August. Based on measurement ofphoton flux density and temperature, the diurnal pattern in leaf [C02] may be generally controlled by expected photosynthetic rates. It is hypothesized that seasonal variation in leaf [C02] may be a function of variation in microbial (soil) respiration. Using dye and slight pressurization, it was confirmed that gas spaces in rhizomes were interconnected with the gas spaces in leaves through the rhizome-shoot transition. From anatomical measurements, it was also estimated that over 50% of total leaf volume was occupied by gas spaces and that most of the total gas-space volume in plants was in the shoot. Photosynthetic rate in C3 plants, like cattail, can increase with increasing [C02] under natural conditions. For this reason, cattail and other emergent wetland plants possessing continuous gas-space pathways appear to have a significant carbon supplement as compared to other C3 plants growing in well-aerated soils. The purpose of this study was to determine the diurnal and seasonal patterns of CO2 concentration ([C02]) in leaf gas spaces for the common wetland emergent, Typha la

Natural wetlands perform significant sewage treatment, but artificial reedbeds are likely to be more reliable and effective. The processes responsible for purification in wetlands and reedbeds are described in this paper, together with an outline of the experimental reedbeds which have been established in the UK up to 1987. Major research needs are outlined.

Roots of Typha latifolia L. exposed to Fe2+ under reduced conditions in solution culture developed visible coatings (plaques) of an oxidized Fe compound that extended as much as 15-17 ,um into the rhizosphere. Iron concentrations were significantly less and discoloration was not apparent on the surface of roots exposed to Fe-(BPDS)3, Fe3+, Fe-EDDHA, and FeEDTA. The extent of plaque formation increased with the concentration of Fe2+ in solution and with pH of the solution in the range of 3.0 to 4.6. Above pH 4.6, oxidation of Fe2+ in the culture solution may have reduced precipitation of Fe on the root surface. Plaque development was most extensive approximately 1.0 cm from the root tip, but all root surfaces showed some Fe staining. Scanning electron micrographs of plaqued roots, grown both in solution culture and in the field, provided support for a model of cast formation by oxidation and precipitation of Fe on external cell surfaces.

Histochemical determinations for storage of carbohydrates in rhizomes, roots, and young shoots of Typha latifolia L. (Typhaceae) were conducted during the overwintering period from November to April. Early winter analysis showed that rhizomes and roots contained large amounts of starch (45.03% and 22.80% dry weight, respectively). The major storage tissue was parenchyma of the rhizome central core. From winter into spring a gradual decrease in storage starch in the rhizome and root occurred concurrently with starch accumulation near zones of rapid development in young shoots (buds), but the rhizome retained much starch (27.40%o dry weight) into the start of its 2nd yr. HIGH LEVELS of productivity have been reported in various cattail species by Bernard and Bernard (1973, 1977), Boyd (1970), Boyd and Hess (1970), McNaughton (1966), and Westlake (1965). After McNaughton (1966) implicated the underground organs of Typha latifolia as winter storage organs, Fiala (1971) related changes in growth of 1- and 2-yr clonal emergent shoots in T. latifolia to changes in rhizome biomass during the growing season (late spring to early fall). Since there was so little information relating stored energy sources to tissue localization, the present study was undertaken to determine the tissue and organ specificity and the amount of starch storage during the overwinter period (late fall to early spring) in Typha latifolia, as implicated by McNaughton (1966).

Morphogenetic pulsations in the intercalary meristem of the leaf of Typha latifolia (Typhaceae) produce regular alternating sequences of vascular and stellate-celled diaphragms separated at first by rib-meristem derivatives. The collapse of these derivatives in the region of elongation in and above the intercalary meristem, and the separation of the diaphragms from each other, produce a mature compartmentalized leaf, the compartments bridged by porous

The effects of variable N and P availability on nutrient uptake, nutrient recovery from dying leaves, and biomass production in three species of marsh graminoids were studied in a growth chamber experiment. "Availability" was defined as the total amount of N or P added to each pot over the duration of the experiment. The species were Carex lacustris, Calamagrostis canadensis, and Typha latifolia. Responses were evaluated in terms of three "efficiencies": (1) efficiency of uptake, or the proportion of available N or P taken up by the plants; (2) efficiency of recovery, or the removal of nutrients from dying leaves as a proportion of the N or P content of mature leaves; and (3) efficiency of use, or the ratio of total biomass to total N or P mass in the whole plant. In all three species, as N or P availability increased, all three efficiency indexes decreased. There was evidence for N x P interaction in regulating efficiency of N or P uptake, but not the other two indexes. Implications for ecosystem nutrient cycling are discussed, with the conclusion that, as nutrient inputs to an ecosystem increase, nutrient losses from the system and nutrient turnover in the vegetation should also increase.

The movement of methane (CH4) from anaerobic sediments through the leaves, stems, and flowers of aquatic plants and into the atmosphere was found to provide a significant pathway for the emission of CH4 from the aquatic substrates of flooded wetlands. Methane concentrations well above the surrounding ambient air levels were found in the mesophyll of 16 varies of aquatic plants and are attributed to transpiration, diffusion, and pressure-induced flow of gaseous CH4 from the roots when they are embedded in CH4-saturated anaerobic sediments. Methane emissions from the emergent parts of aquatic plants were measured using floating chamber techniques and by enclosing the plants in polyethylene bags of known volume. Concentration changes were monitored in the trapped air using syringes and gas chromatographic techniques. Vertical profiles of dissolved CH4 in sediment pore water surrounding the aquatic plants' rhizomes were obtained using an interstitial sampling technique. Methane emissions from the aquatic plants studied varied from 14.8 mg CH4/d to levels too low to be detectable. Rooted and unrooted freshwater aquatic plants were studied as well as saltwater and brackish water plants. Included in the experiment is detailed set of measurements on CH4 emissions from the common cattail (Typha latifolia). This paper illustrates that aquatic plants play an important gas exchange role in the C cycle between wetlands and the atmosphere.

The seasonal contribution of living Typha components to the buoyancy of floating mats was investigated in a diked, freshwater impoundment near the head of the Bay of Fundy in New Brunswick, Canada. The objectives were (1) to examine the potential influence of a dominant, mat—building species on hydrologic conditions at the mat surface, and (2) to predict whether a complete killing of the dominant species could cause mats to sink. The Typha component contributing most to mat buoyancy was the rhizomes, which added a net buoyancy pressure of °20 Pa throughout the growing season. The seasonal maximum buoyancy contribution of 28 Pa for all living Typha components combined was reached in spring, followed by a decline to 11 Pa in late summer as the aboveground shoots developed. This positive and seasonally variable contribution of Typha to mat buoyancy is expected to be most important during the early stages of mat development, when mats are thin and composed largely of living, belowground organs. However, on older and thicker mats the living Typha is less important because of the large volumes of gas bubbles from anaerobic decomposition that are trapped in the dead organic material. For the 50 cm thick floating mats under study, it is concluded that trapped gas is the main cause of buoyancy and would lead to the continued flotation of mats even if the living Typha were removed. Implications of the results are discussed in relation to the resiliency of floating mat systems.

The two species of Typha common in the southeastern United States, T. latifolia and T. domingensis differ substantially in their tolerance to deep water. The objective of this study was to examine the morphology and biomass allocation of these two species to determine if they have similar phenotypic responses to water depth. Replicate monocultures of the two species were established at a range of water depths in an artificial pond and allowed to grow for three growing seasons. At the end of the experiment, subsamples were harvested for determination of plant morphology as well as above- and belowground biomass. Both species of Typha showed increases in maximum height with increasing depth. The species less tolerant to deep water (T. latifolia) allocated more of its biomass to leaves with increasing water depth. In contrast, the deep water species (T. domingensis) showed increased total size of each ramet but a fixed percentage of biomass in leaves with increasing water depth. Both species had a decreasing incidence of flowering and decreasing shoot density with increasing water depth. In general, these species conform to expectations based on considerations of how their carbon budgets would be affected by water depth.