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In 2020, the first record of Wolffia arrhiza was made in Novosibirsk region (Western Siberia) in a floodplain lake. Wolffia arrhiza formed vast stands with an area of hundreds of square meters and with high productivity. Besides monodominant communities, it was met as a component of the cenoses of such hydrophytes as Stratiotes aloides and Hydrocharis morsus-ranae, as well as of the helophyte communities formed by Typha latifolia and Eleocharis mamillata. According to local residents, Wolffia was observed as abundant for some years; thus, most likely, the population winters safely at the latitude of Novosibirsk. The most likely source of Wolffia arrhiza appearance in the lake was an accidental introduction from an aquarium, although the possibility of this plant entering the lake in high-water years from the wastewater of the municipal settling tank of Novosibirsk sewage waters also exists.

Invasive species negatively impact vegetation communities. Invasive European common reed [Phragmites australis (Cav.) Trin. ex Steud. ssp. australis] is rapidly spreading throughout North American wetlands. As such, the suppression of P. australis populations is a goal of many managers, as its removal should provide an opportunity to restore native vegetation communities. In Ontario, managers applied a glyphosate-based herbicide to more than 400 ha of P. australis in ecologically significant coastal marshes, representing the first time this tool was used over standing water to suppress an invasive species in Canada. Using a before–after–control–impact monitoring design, we evaluated the efficacy of glyphosate-based herbicide at removing P. australis along a water-depth gradient and assessed the recovery of the vegetation community for 2 yr after treatment in relation to reference conditions. We found that herbicide suppressed more than 99% of P. australis 1 yr after treatment and worked effectively along the entire water-depth gradient (10 to 48 cm). However, the post-treatment vegetation community remains distinctive from reference marsh 2 yr after treatment. In many plots where P. australis was removed, nonnative European frog-bit (Hydrocharis morsus-ranae L.) is now dominant, likely aided by high lake-water levels.

European frog-bit (Hydrocharis morsus-ranae L.; EFB) is a free-floating aquatic plant invasive in Canada, the United States and India. It is native to Europe and northern and western Asia and is believed to have first been introduced to North America in Ottawa, Ontario in 1932. It has since spread by way of the St. Lawrence River and connected waterways to southern Ontario and Quebec and parts of the northern United States. Invasive European frog-bit occurs in freshwater coastal wetlands and inland waters, where it can form dense mats that have the potential to limit recreational and commercial use of waterways, alter water chemistry and impact native species and ecosystems. Data on the past and present distribution of this invasive species provide geospatial information that can be used to infer the pattern of invasion and inform management and monitoring targeted at preventing secondary spread. Our EFB dataset contains 12,037 preserved specimen and observation-based occurrence records, including 9,994 presence records spanning two Canadian provinces and ten U.S. states and 2,043 absence records spanning five U.S. states. The aggregated EFB dataset provides a curated resource that has been used to guide a Michigan management strategy and provide information for ongoing efforts to develop invasion risk assessments, species distribution models and decision-support tools for conservation and management. Specimen-based and observation-based occurrence data were accessed through nine digital data repositories or aggregators and three primary sources. Twenty-six percent of the data are new records not previously published to a data repository or aggregator prior to this study. We removed duplicate data and excluded records with incorrect species identifications. Occurrence records without coordinates were georeferenced from recorded locality descriptions. Data were standardised according to Darwin Core. This aggregated dataset is the most complete account of EFB occurrence records in its North American invasive range.

Background Hydrocharis L. and Limnobium Rich. are small aquatic genera, including three and two species, respectively. The taxonomic status, phylogenetic relationships and biogeographical history of these genera have remained unclear, owing to the lack of Central African endemic H. chevalieri from all previous studies. We sequenced and assembled plastomes of all three Hydrocharis species and Limnobium laevigatum to explore the phylogenetic and biogeographical history of these aquatic plants. Results All four newly generated plastomes were conserved in genome structure, gene content, and gene order. However, they differed in size, the number of repeat sequences, and inverted repeat borders. Our phylogenomic analyses recovered non-monophyletic Hydrocharis. The African species H. chevalieri was fully supported as sister to the rest of the species, and L. laevigatum was nested in Hydrocharis as a sister to H. dubia. Hydrocharis-Limnobium initially diverged from the remaining genera at ca. 53.3 Ma, then began to diversify at ca. 30.9 Ma. The biogeographic analysis suggested that Hydrocharis probably originated in Europe and Central Africa. Conclusion Based on the phylogenetic results, morphological similarity and small size of the genera, the most reasonable taxonomic solution to the non-monophyly of Hydrocharis is to treat Limnobium as its synonym. The African endemic H. chevalieri is fully supported as a sister to the remaining species. Hydrocharis mainly diversified in the Miocene, during which rapid climate change may have contributed to the speciation and extinctions. The American species of former Limnobium probably dispersed to America through the Bering Land Bridge during the Miocene.

Stratiotes aloides (Hydrocharitaceae) is a member of hydromacrophyte communities, which are widespread in the waterbodies of Eurasia. In the course of our study, which covered both fieldwork across a large part of the species range as analysis of published sources, we determined that S. aloides is a Pliocene relic showing a boreal-sublatitudinal sub-Eurasian range with a small North American enclave. Its populations are generally quite stable across much of their current range. However, in Western, Central and southern Europe and in the South of European Russia, both local population sizes and area of occupancy of S. aloides populations decline significantly, mainly due to habitat degradation. Regeneration via seed is of particular importance to the plant in extreme conditions, and also for maintaining or increasing the genetic diversity of its populations. Seeds are usually more easily dispersed, across a wider area, than vegetative propagules produced by the plant. Yet, in some populations sexual reproduction is hindered by spatial isolation of the plants of different sexual types and prevalence of gynomonoecious populations. On the other hand, vegetative (clonal) propagation of S. aloides can result in locally-high biological productivity, and extensive occupation of water area by the plant at individual sites. Populations of S. aloides have been found to co-occur with at least 134 other macrophyte species variously present. Highly constant species (present in more than 50% of communities containing S. aloides) include Ceratophyllum demersum, Hydrocharis morsus-ranae, Lemna trisulca, Potamogeton perfoliatus, Spirodela polyrhiza, and Utricularia vulgaris. This species prefers mesotrophic, β-mesosaprobic freshwaters, and detrital, muddy-clayey bottom soils.

Se aporta la primera cita de Hydrocharis laevigata (Humb. & Bonpl. ex Willd.) Byng & Christenh. para la flora andaluza. El hallazgo constituye la segunda cita de este hidrófito para la Península ibérica, en donde se conocía solo de la provincia de Madrid. Hydrocharis laevigata (Humb. & Bonpl. ex Willd.) Byng & Christenh. is reported for the first time for the Andalusian flora. This is the second record of this hydrophyte for the Iberian Peninsula, where it was known only from the province of Madrid.

Invasive Phragmites australis (European Common Reed) is rapidly spreading throughout North American wetlands, with negative impacts on wildlife and native plants. The removal or suppression of P. australis is desired to provide an opportunity for native vegetation and wetland fauna to recover. In Ontario, managers applied a glyphosate-based herbicide to >400 ha of P. australis in ecologically significant Great Lakes coastal marshes, representing the first time this tool was used over standing water to suppress P. australis in Canada. Using a replicated Before-After-Control-Impact monitoring design, we 1) evaluated the efficacy of glyphosate-based herbicide at suppression P. australis along a water depth gradient and 2) assessed the recovery of the vegetation community for two years after treatment in relation to local reference conditions. We found that herbicide reduced live P. australis stem densities by over 99% the first year after treatment and about 95% the second year post-treatment. Treatment was equally effective along the entire water depth gradient (10 – 48 cm). The initial ‘suppression’ focused management was successful, but sustained monitoring and ‘containment’ focused follow-up treatment will be required to prevent reinvasion. Two years after treatment, the vegetation community does not resemble reference conditions. Although some treated plots initially increased in similarity to the vegetation communities typical of reference areas, many plots where P. australis was suppressed are on a novel trajectory comprising a vegetation community dominated by non-native Hydrocharis morsus-ranae. Secondary invasions represent a major challenge to effective recovery of native vegetation after P. australis control.

Lostak, Michal/0000-0003-0392-0702; WOS: 000399041000010 In this study, accumulation and distribution of Pb, Cu, Zn, Co, Ni, Mn and Fe in water, bottom sediments and four plant species (Myriophyllum verticillatum, Hydrocharis morsus-ranae, Nymphaea alba and Typha latifolia) were investigated in cernek Lake of Kizilirmak Delta. The Kizilirmak Delta is one of the largest natural wetlands of Turkey and it is protected by the Ramsar convention since 1993. Selected physico-chemical parameters such as pH, conductivity and dissolved oxygen and also trace metal concentrations were monitored in water. All the parameters obtained were found higher than that of the national standards for the protected lakes and reserves. The accumulated amounts of various trace metals in bottom sediments and wetland plants were found in the following order of Fe > Mn > Zn > Ni > Co > Cu > Pb and Fe > Mn > Zn > Ni > Co respectively. The historical trace metal intake of Myriophyllum verticillatum, Hydrocharis morsus-ranae, Typha latifolia and Nymphaea alba were obtained higher than that of the toxic metal levels and these plants may be accepted as accumulators for the detected trace metals and also bio-indicators in the historically polluted natural areas. (C) 2016 International Research and Training Centre on Erosion and Sedimentation/the World Association for Sedimentation and Erosion Research. Published by Elsevier B.V. All rights reserved. Ondokuz Maps University Scientific Research Project [PYO.FEN.1904.10.013] This study was supported by Ondokuz Maps University Scientific Research Project no: PYO.FEN.1904.10.013.

The genus Hydrocharis L. includes three geographically isolated species. Analysis of the actual data (32 thousand geographical locations and 1946 herbarium sheets) covering the period 1765–2019 made it possible to clarify the nature of the distri- bution of these species and its changes. Hydrocharis morsus-ranae L. has disjunctive Eurasian – North American temperate range, with a massive North American en- clave, the formation of which began in the 1930–1940s. The range of Hydrocharis dubia (Blume) Backer is disjunctive Southeast Asian – Australian subboreal-tropical, Australia enclave began forming in the 1850–1870s. Hydrocharis chevalieri (De Wild.) Dandy is a macrothermal Central African equatorial endemic. Current threat status of all species may be estimated as Least Concern. The mean annual temperature is the most contrasting feature of the distribution areas of the species, water depth, bottom soil type and hydrochemical composition have lower impact. Prognostic models of the potential distribution of the tagged species have been made.

The temporal variations in plant chemistry connected with its life cycle may affect the cycling of elements in an ecosystem as well as determine the usefulness of the species in phytoremediation and bioindication. In this context, there is a gap in knowledge on the role of floating plants for elements cycling in aquatic reservoirs. The aim of the study was to determine if there are variations in Hydrocharis morsus-ranae (European frog-bit) bioaccumulation capacity and the growth rate of its population during the growing season and to test the impact of environmental pollution on these features. The content of macroelements (Ca, K, Mg, N, Na, P, S) and trace metals (Cd, Co, Cu, Cr, Hg, Fe, Mn, Ni, Pb, Zn) was determined in H. morsus-ranae collected monthly from June to October from habitats differing in environmental contamination. The results showed that the highest content of most trace metals (Co, Cr, Cu, Hg, Mn, Ni, Zn) and some nutrients (N, P) in plants as well as the greatest bioaccumulation efficiency occurred simultaneously in the beginning of the growing season. In the following months, a dilution effect (manifested by a decrease in content) related to the rapid growth was observed. Co, Mn, and Ni content in plant tissues reflected the level of environmental contamination throughout the growing season which makes H. morsus-ranae a potential biomonitor of pollution for these metals. Considering the great bioaccumulation ability, high sensitivity to contamination, and low biomass of European frog-bit in polluted systems, further investigation is required to assess the real phytoremediation capability of the species.

The assessment of trace metal pollution in aquatic environments remains a challenge. Chemical methods are insufficient and bioindicators seem to be the most promising alternative. Finding an adequate species is important to ensure accurate data. The combined use of several bioindicators may help to overcome the limitations of species’ spatial distribution and specific reactions. The aims of the present study were to compare the contents and bioaccumulation capability of 11 trace elements in Ceratophyllum demersum and different organs of Hydrocharis morsus-ranae and to validate H. morsus-ranae as a bioindicator of pollution in aquatic reservoirs using C. demersum, an established bioindicator, as a reference species. The application of several statistical techniques allowed us to identify similarities in accumulation patterns and concentration gradients between the two species. The results showed that concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, Rb, Zn, V in C. demersum and roots of H. morsus-ranae were similar and mostly higher than in the leaves and stems of H. morsus-ranae. The contents of Cd, Co, Cr, Li, Mn, Ni, Rb, V, Zn were positively correlated. The inner transport of metals in H. morsus-ranae was limited (TF 103) of Ni and Zn, and H. morsus-ranae also of Cu and Pb. Frog-bit roots were chosen to be most promising in bioindication. Major axis regression analysis showed that the uptake of Cd, Cr, Co, Li and Pb was similar in the two species. Neural networks demonstrated substantial uniformity in responses of C. demersum and roots of H. morsus-ranae to the type of anthropogenic activity and land use and similar spatial distributions of Cd, Cr, Co, Li and Pb. When Nemerow Pollution Index was applied, both species showed congruent gradients of contamination. Thus, H. morsus-ranae was validated as a reliable bioindicator of trace metal pollution in freshwater.

Decomposition is one of the fundamental processes that influence the recycling of elements in the ecosystem. Environmental pollution and eutrophication may affect plant decay and, therefore, lead to disturbances in detritus-based food webs. The objective of the study has been to describe changes in biomass loss and macroelements (C, Ca, K, Mg, N, Na, P, S) and trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) contents during breakdown of Hydrocharis morsus-ranae L. (European frog-bit). The questions underlying the study were: Does element concentration in plant litter or the environment affect the rate and pattern of H. morsus-ranae decomposition? What are the chemical predictors of the H. morsus-ranae detritus decay rate? An in situ experiment on decomposition was conducted using the litter-bag technique. H. morsus-ranae was found to be a fast decomposing macrophyte. The Na, Mn and K release rates were the largest, and the concentrations of C, N, P, S and trace metals in litter increased during the decay. In study sites that differed in element concentrations in fresh plant material and water plants had different decay rates and final element contents. Both the inhibitory effect of contaminants (Cd and Ni) and/or stimulatory effect of nutrients (P, N) and essential elements, such as Fe, Mg and Mn, could cause variation in decomposition observed between the study sites.

The aim of present study was to investigate the level of trace metals and macroelements in Hydrocharis morsus-ranae collected from regions differing in the degree and type of pollution. Concentrations of 17 macro- and microelements were determined in roots and shoots of European frogbit as well as in water and bottom sediments from 30 study sites. Plants differed in concentrations of elements and bioaccumulation capacity depending on the characteristics of dominant anthropogenic activities in the vicinity of the sampling site. Shoots of H. morsus-ranae growing in the vicinity of organic chemistry plants and automotive industry contained particularly high levels of Cd, Co, and S. Plants from area close to heat and power plant, former ferrochrome industry and new highway, were distinguished by the highest concentrations of Cr, Cu, and Pb. European frogbit from both these regions contained more Fe, Hg, Mn, Ni, and Zn than plants from agricultural and recreational areas. The concentrations of alkali metals and Co, Fe, and N in H. morsus-ranae were elevated in relation to the natural content in macrophytes irrespectively to their content in the environment. Based on the values of Bioaccumulation and Translocation Factors, European frogbit is an accumulator for Co, Cr, Cu, Fe, K, Mn, Ni, Pb, and Zn and a good candidate for phytoremediation of water polluted with Co, Cu, Hg, K, Mn, and Ni. The amount of Co and Mn removed from water and accumulated in the plant biomass during the vegetation season was considerably high.

European frogbit (Hydrocharis morsus-ranae L.) is an invasive floating plant that negatively affects native plants in freshwater ecosystems. We conducted a field mesocosm experiment in Oneida Lake, New York (USA), to study the effect of frogbit cover on macroinvertebrates and to test the effects of 2 physical control methods, hand pulling and shading, on macroinvertebrate assemblages. We used Hester–Dendy samplers and Ekman grabs to collect surface/phytophilous and benthic macroinvertebrates. Metrics including density of different types of organisms, total abundance, taxon richness, and Simpson’s diversity index were compared between control methods. Frogbit cover had significant positive effects on mollusk density, amphipod density, taxon richness, and Simpson’s diversity in the Hester–Dendy surface samples. Sites with frogbit had significantly fewer benthic worms and more chironomids (Hester–Dendy bottom samples) and possibly higher diversity of benthic macroinvertebrates (Ekman samples). These ...

The influence of the submerged plants Ceratophyllum demersum L. and Elodea canadensis Michx. and the floating plant Hydrocharis morsus-ranae L. on the species composition and quantitative parameters of a zooplankton community was studied experimentally. Among submerged vegetation, the development of the predaceous calanid Heterocope saliens Lilljeborg was suppressed. An increase in the number of zooplankter species was observed in all experimental ecosystems with hydrophytes. The species similarity of zooplankton was higher between communities with plants of the same ecological group than with plants of different groups. The highest average zooplankton biomass, as determined by the abundance of Daphnia longispina O.F. Muller and Simocephalus vetulus (O.F. Muller), was observed in experiments with Elodea. The highest average abundance over the experimental period was recorded among Ceratophyllum, where the abundance of Rotifera, chydorids, and copepods common in hydrophyte beds was higher than in other versions of the experiment.

The aim of this study was to describe a botanical classification for lakes in Serbia based on vegetation assemblage, basic water quality parameters and geographic region. Between 2008 and 2010 records from more than 1000 releves were collated into one dataset. All releves were derived from synoptic syntaxon tables (1956–2010). In order to fill geographical and methodological gaps in the database, additional field research was carried out during 2008, 2009 and 2010 at 18 new locations, producing a final total of 98 sites, 748 releves and approximately 22,500 floristic records. Cluster analysis using TWINSPAN (Two-Way INdicator SPecies ANalysis) revealed two main lake vegetation types (LVT1 and LVT2). LVT1 is characterized by typically species-rich, eutrophic sites with Ceratophyllum demersum dominant, followed by Hydrocharis morsus-ranae, Lemna minor, Salvinia natans as constants, while LVT2 comprises species-poor, meso-eutrophic sites with Myriophyllum spicatum constant. These two main lake vegetation types are further divided into four sub-types (LVT1a, LVT1b, LVT2a, LVT2b), and seven site groups. Instead of predicting the vegetation lake groups using predefined physico-chemical categories, the reverse approach has been applied. Altitude and BOD/COD values (as proxies of trophic status) verified the TWINSPAN-derived classification based on lake vegetation. Brief reviews are given to describe national conservation strategy. The results from this study illustrate their value in amplifying descriptions of sites already recognized as important nationally and internationally. In addition, Groups 5 and 6 are considered a potential conservation resource, with six site-targets in particular, representing specific oases for many aquatic species whose natural habitats are endangered by human activity or natural succession. Copyright © 2011 John Wiley & Sons, Ltd.

Turions are overwintering, dormant organs, produced by aquatic plants. In spring, aerobic dark respiration (RD) and photosynthetic rates (PN) were measured as criteria of metabolic activity and photosynthetic capacity in dormant turions of 7 temperate aquatic plant species. These rates were also measured in old, original turion segments and in the newly formed shoots of sprouting turions. Two non-carnivorous rooting species (Caldesia parnassifolia, Hydrocharis morsus-ranae) and 5 carnivorous rootless species (Aldrovanda vesiculosa, Utricularia vulgaris, U. australis, U. stygia, U. bremii) were studied. RD values of dormant turions per unit fresh weight (range 1.1– 5.4 mmol kgFW h ) were significantly lower (1.9 –13 times) for all species, except A. vesiculosa, than those for old segments of sprouting turions (range 5.2 –14 mmol kgFW h ). However, RD and PN values of old and newly formed turion segments in U. australis and U. stygia were similar. PN values of dormant turions under optimum conditions were either very low or negative, while PN values of old segments of sprouting turions of all species except H. morsus-ranae were very high (18 – 94 mmol kgFW h ). In a Nand P-free solution, turions of all species except A. vesiculosa formed distinct new organs after 6 – 20 days. In conclusion, the intensity of metabolism (both RD and PN) in sprouting turions reaches the level of adult shoots or leaves of the same species. Turions of aquatic plants also function as important storage organs for mineral nutrients (N, P, S and Mg) to ensure the growth of new organs.

Klátovské rameno is the lowland slow-flowing groundwater feed eutrophic tributary of the Malý Dunaj River (Danube Plain), where our study of temporal changes of aquatic macrophytes vegetation was realised in 1999 and 2005. For survey of aquatic vascular macrophytes the Kohler’s method (Janauer 2003) was used, which is compliant with European standard EN 14184. Altogether 35 aquatic macrophyte species were recorded during the survey. Nuphar lutea persisted as the most dominant species in 1996 and 2005. Species diversity increased slightly after the nine years: ten species immigrated to the watercourse. The changes in species abundance have shown weak differences, however the abundance of Sparganium emersum has increased markedly. Alien species Elodea canadensis and both S. emersum and Hydrocharis morsus-ranae significantly enlarged their distribution in the stream. The ecological quality of the river, based on the aquatic macrophytes assessment criteria, was slightly impaired after nine years, but still 90% of its studied course has a high or good ecological status.

The content of macronutrients (N, P, K, Na) and heavy metals (Fe, Mn, Zn, Cu, Ni, Pb, Cd, Co) in plant samples of dominant aquatic macrophytes (Ceratophyllum demersum, Phragmites australis, Trapa natans, Hydrocharis morsus-ranae, Nymphaea alba, Nymphoides peltata, Salvinia natans) from the river Jegricka (Serbia) is presented. Macronutrients content in plant tissue was above necessary limits for plant maximum growth indicating to substantial bioavailability of those elements typical for eutrophic environment. Content of investigated nutrients and heavy metals varied in relation to plant species. Ceratophyllum demersum turned out to be best bioaccumulator for P, K, Fe, Mn, Cu, Ni, Pb, and Co. Salvinia natans accumulated high amounts of N, P, K, Na, and especially Cu and Zn. Nymphaea alba accumulated highest recorded amounts of N and Na. Hydrocharis morsus-ranae accumulated very high amounts of N, P, K, Na, Pb, and Mn. Because of its fast growth, large abundance and homogeneous distribution on this locality, Phragmites australis might have high potential in use for phytoextraction of macronutrients and heavy metals. The application of macrophytes as indicators might be limited depending on the varying of environmental conditions on different localities.

The extent to which invasive aquatic plants move via accidental inclusion in aquatic plant orders or sale of prohibited species is unknown. Forty orders were placed to 34 aquatic plant vendors across the US between May and September 2001 to determine the prevalence of movement into Minnesota via horticultural trade. Federal noxious weeds or Minnesota prohibited exotic species were acquired 92% of the time they were ordered and included Alternanthera sessilis, Butomus umbellata, Hydrocharis morsus-ranae, Potamogeton crispus, and Lythrum salicaria. Ninety three percent of orders received from aquatic plant vendors contained a plant or animal species not specifically requested; 10% of these purchases contained federal noxious weeds or Minnesota exotic species. Lemna minor was the most common incidental receipt found per taxa and per purchase, although Hydrilla verticillata, Lythrum salicaria, Salvinia molesta, and Potamogeton crispus (all prohibited taxa) were also found. Misidentified plants were found in 18% of the orders; unordered seeds in 43%. The sale and transport of prohibited aquatic plants likely presents the greatest risk associated with the aquatic plant trade. Other important factors include misidentification leading to the unintentional sale of invasive plants and the incidental inclusion of species during translocation.

European frog-bit (Hydrocharis morsus-ranae L.), a free-floating, stoloniferous aquatic, is native to Europe and parts of Asia and Africa. It was discovered in Canada in 1932 in Ottawa, but earlier introduction is possible. By 1955 its North American distribution extended from Ottawa to Montreal. By 1980 it had extended southwest to Lake Ontario and northeast to Quebec City. Recently it has spread throughout much of the central and southwestern parts of southern Ontario, and further into northern New York and Vermont and eastern Michigan. The maximum rate of spread has been 15.6 km yr-1. Reproduction by seeds is rarely reported but vegetative reproduction is very important in spread and colonization. In the fall, turions separate from the plant, sinking to the bottom where they overwinter. In the spring, these turions grow into small floating rosettes. Extremely rapid stoloniferous growth during the summer months results in the formation of large masses of interlocking plants that diminish native submerged aquatic plant communities by reducing available light. It is also of importance in limiting water flow in irrigation systems and restricting water traffic, thereby hindering recreational activity. Management has been largely mechanical. Hydrocharis morsus-ranae is a food plant for several water birds, rodents, fish and insects. Key words: Hydrocharis morsus-ranae, weed biology, aquatic, Canada distribution, alien, European frog-bit, invasive spread

The research on the amino acids (valine, arginine, tryptophan, methionine, lysine, histidine, phenylalanine, isoleucine) and water-soluble vitamins (B1, B2, B6, C) content in species of the family Hydrocharitaceae, growing in Western Siberia (Elodea canadensis, Stratiotes aloides Hydrocharis morsus-ranae, Hydrilla verticillata), has been executed.Fiveindispensable (valine, isoleucine, lysine, tryptophan, phenylalanine) and two dispensable(arginine, histidine) amino acids have been discovered at examined species of family. It has been found that all examined Hydrocharitaceae have a comparatively high content of valine (H. morsus-ranae has a maximum valine content ((420 ± 30) × 10-7 g / 100 g)). The high content of vitamin C (S. aloides ((770 ± 30) × 10-7) and H. morsus-ranae ((750 ± 30) × 10-7 g / 100 g) have a maximum content) and the equally low content in all examined species of vitamin B6 (at a rate of ((19 ± 2) × 10-7 g / 100 g) are typical., Выполнено исследование содержания аминокислот (валина, аргинина, триптофана, метионина, лизина, гистидина, фенилаланина, изолейцина) и водорастворимых витаминов (В1, В2, В6, С) у видов семейства Hydrocharitaceae, произрастающих на территории Западной Сибири (Elodea canadensis, Stratiotes aloides, Hydrocharis morsus-ranae, Hydrillaverticillata).У исследуемых представителей семейства обнаружены пять незаменимых (валин, изолейцин, лизин, триптофан, фенилаланин) и две заменимых (аргинин, гистидин) аминокислоты. У всех исследуемых Hydrocharitaceae наблюдается сравнительно высокое содержание валина (максимальное у H. morsus-ranae(420 ± 30) × 10-7 г/100 г). Характерным является высокое содержание витамина С (максимальное у S. aloides– (770 ± 30) × 10-7 и H. morsus-ranae– (750 ± 30) × 10-7 г/100 г) и одинаково низкое у всех исследуемых видов витамина В6 (на уровне (19 ± 2) ×10-7 г/100 г).

WOS: 000341024400008 PubMed: 25174426 In this study, concentrations of heavy metals (Fe, Mn, Ni, Co, Zn, Cu, and Pb) were measured in water bodies including streams, bottom sediments and various wetland plants of Kizilirmak Delta. Kizilirmak Delta is one of the largest and the most important natural wetlands in Turkey and has been protected by Ramsar convention since 1993. The heavy metal concentrations in water were found lower than that of national standards for protected lakes and reserves. In bottom sediments and wetland plants, however, the accumulated amounts of different heavy metals varied in the following order: Fe>Mn>Zn>Ni>Co>Cu>Pb, and Fe>Mn>Zn>Ni>Co respectively. Heavy metal uptake of Hydrocharis morsus-ranae and Myriophyllum verticillatum plants among others were found far above the toxic levels and they might be used as bio-indicators and heavy metal accumulators in polluted natural areas. Ondokuz Mayis UniversityOndokuz Mayis University [PYO.FEN.1904.10.013] This study was supported by Ondokuz Mayis University scientific research project No. PYO.FEN.1904.10.013.

The study of the content of 14 chemical elements (P, Na, Mg, K, Ca, Cr, Mn, Fe, Co, Cr, Zn, Se, Pb, Al) in five species of the Hydrocharitaceae family growing in the territory of the Western Siberia ( Elodea canadensis, Stratiotes aloides , Hydrocharis morsus-ranae , Hydrillaverticillata ) was implemented. Inductively coupled plasma mass spectrometry was used in the study to clarify the elemental profiles of certain species. Despite the similarity of the obtained series of the biological absorption of elements, a number of specific features are identified. For example, H . morsus - ranae has the lowest concentration of Fe (135±1) and Mn (24,4±0,4), E. canadensis is characterized by the lowest concentration of Al (0,93±0,01), H . verticillata − Ca (2890±40). E . canadensis in comparison with other studied species has a higher concentration of Na (28400±600), K (13740±90), Ca (4250±40), Fe (750±10) and Mn (185±2), S . aloides is characterized by higher concentration of Mg (30850±60), Ca (4490±40) and P (2910±40), H. verticillata − Al (3,20±0,02). The results of the cluster analysis of the chemical element content show the considerable isolation of S. aloides from the rest of the family.

SHAFFER-FEHRE, M., 1991. The endotegmen tuberculae: an account of little-known structures from the seed coat of the Hydrocharitoideae (Hydrocharitaceae) and of Najas (Najadaceae). The sub-cellular protuberances from the inner tegmen layer have been given various names in earlier literature. Here named ‘endotegmen tuberculae’, they vary in shape, size and density of distribution in the endotegmen of different taxa. These characteristics make them useful for taxonomic research at both genus and species level. Their shape is a major consideration in transferring Hydrocharis dubia to the genus Limnobium. A further structure, ‘exotegmen tuberculae’, has been observed for the first time. This paper gives a survey of these structures and illustrates their taxonomic importance and its implications.

Using environmental parameters we studied the distribution of two endangered species, Hydrocharis morsus-ranae L. and Rumex hydrolapathum Huds., in a low-lying marshland of the Swiss Plateau, a region in which aquatic vegetation is particularly threatened. A large part of the study site is regularly mown by a machine for site management purposes. The caterpillar mower digs ruts, which are especially pronounced along the tracks used to reach the mown compartment. To assess the effects of site management on these species, we have tested six environmental parameters (vegetation unit, water conductivity, water supply indicated by altitude, time elapsed since the last cut, distance from major ruts and disturbance of major ruts) that can potentially influence plant distribution. All the plots of these two species have been found in mowed compartment, which seems to indicate a correlation between site management operations and occurrences. The other factors driving the distribution of these plants are vegetation unit, distance from major ruts and water supply.

Hydrocharis morsus-ranae Linnaeus, Species Plantarum 2: 1036. 1753. "Habitat in Europae fossis limosis." RCN: 7474. Lectotype (Cook & L����nd in Aquatic Bot. 14: 185. 1982): Herb. Linn. No. 1189.1 (LINN). Generitype of Hydrocharis Linnaeus. Current name: Hydrocharis morsus - ranae L. (Hydrocharitaceae)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part H), pp. 557-585 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 579, DOI: 10.5281/zenodo.291971

The pollen morphology of 11 genera and 11 species of the Hydrocharitaceae and one species of the Najadaceae was studied using scanning and transmission electron microscopies, and the exine structures and sculptures are discussed in relation to pollination mechanisms and the molecular phylogeny. The pollen grains of the Hydrocharitaceae are spherical, inaperturate, and form monads or tetrads, while those of the Najadaceae are elliptical, inaperturate, and form monads. The entomophilous genera Egeria, Blyxa, Ottelia, Stratiotes, and Hydrocharis share pollen grains that have projections like spines or bacula. The anemophilous genus Limnobium has reticulate pollen grains. The hypohydrophilous genera Thalassia and Najas are characterized by pollen grains with reduced exine structures. The pollen-epihydrophilous genera Elodea and Hydrilla have tightly arranged small spinous pollen grains, and the male flower-epihydrophilous genera Enhalus and Vallisneria have reduced reticulate or gemmate exines. Character state reconstruction of the exine structures and sculptures using a molecular phylogenetic tree suggests that variation in the exine is generally correlated with the pollination mechanism; the selective pressures acting on the pollination mechanisms have reduced the exine structure in hypohydrophilous plants and resulted in various exine sculptures that are adapted to the different pollination mechanisms in entomophilous, anemophilous, and pollen-epihydrophilous plants.

Invasive European frogbit (Hydrocharis morsus-ranae L.) has negative environmental and economic impacts in North American water bodies. It is therefore important to develop effective management tools to control this invasive species. This study investigated shading as a control method for European frogbit in both greenhouse and lake mesocosm experiments. A series of shade treatments (0%, 50%, 60%, 70%, 80%, and 100%) were tested in the greenhouse for three weeks. Results showed that the 100% shade was most effective at controlling European frogbit, and other shade treatments greater than 50% were less effective, reducing frogbit biomass up to 38.2%. There were no differences found in temperature between treatments, but dissolved oxygen decreased as shading increased. A lake mesocosm experiment utilizing 0% shade, 70% shade, and 100% shade treatments was performed in a sheltered inlet of Oneida Lake in New York State for over one month. Resulting European frogbit biomass was significantly (25 times) less in areas treated with the 70% shade and nearly zero with the 100% shade. Shading did not affect temperature but improved DO conditions. Results on the shading effects on submerged macrophytes were not conclusive: no significant differences in changes in species richness and abundance between the three groups at the end of studied period suggested no shading effects; significant differences between the beginning and end communities in the 70% shade and the 100% shade but not in the control group indicated significant impacts of shading. This study is the first one to investigate shading as a control method for European frogbit and it is concluded that a moderately high density shade can effective remove European frogbit likely with minor impacts on the environment. More experiments with larger scales and longer time periods are recommended for further investigation.

Elongation of the shoots of three aquatic plants (Hydrocharis morsus-ranae, Regnellidium diphyllum and Ranunculus sceleratus) is stimulated by treatment with ethylene or IAA. The effects of the two hormones are additive, and experiments with an ethylene biosynthesis inhibitor and silver ions indicate that the mechanisms by which ethylene and IAA stimulate growth may be different. Hydrocharis and Ranunculus leaf discs synthesize [(14)C]ethylene from [(14)C]methionine, but no [(14)C]ethylene is formed by Regnellidium, suggesting the existence of an alternative pathway of ethylene biosynthesis in the fern.

Hydrocharis morsus-ranae L. is a Eurasian aquatic plant introduced to North America. It spreads primarily by the rapid production and growth of stolons and overwintering turions but still flowers extensively. The white, trimerous flowers of H. morsus-ranae are emergent and unisexual, with male flowers clustered in a cyme of up to five buds and females always solitary. Both sexes of flowers, once open, last a single day, with individual male flowers opening sequentially from a given inflorescence but not necessarily on successive days. First openings in the corollas of flowers were visible by 0730 and maximum expansion was usually reached by late morning. Anthers dehisce and stigmas become receptive by 0930 with both reaching maxima by midday. The flowers produce a sweet nectar and scent which attract, and are easily accessible to, a wide variety of insects visiting the open bowl-shaped flowers. The most abundant insect visitors to the flowers were Homoptcra (Aphididae) and Hydrellia and Notiphila spp. (Diptera: Ephydridae). Both groups were found to carry small pollen loads and because of their erratic anthophilous behaviour were not considered important in pollination. Although fewer in number, the more specialized hover flies, Toxomerus marginatus (Say) (Diptera: Syrphidae), and solitary bees, Dialictus sp. (Hymcnoptera: Halictidae), were considered more likely to be the primary pollinators. After pollination and the day after anthesis, female flowers are drawn underwater by pedical recurvation and 4–6 weeks later mature into globose berrylike fruits. Fruit-sets were 38.3% in naturally pollinated flowers, 96.5% in bagging experiments with hand-pollinations, and absent in bagging experiments for agamospermy with unopened flowers. These results substantiated that poor fruit-set in some populations was caused by a lack of effective pollinators. Seed densities of 250/m2 were still estimated with the above data.

The present communcation gives cytological data of four taxa covering the families Butomaceae and Hydrocharitaceae. Two cytotypes were noticed in Butomus umbellatus (2n=26, 39). While the basic karyotype in these two taxa was unaltered, there was distinct difference in the size of chromosomes. Polymorphism in respect of chromosome size was noticed in Hydrilla verticillata and Hydrocharis dubia in the populations inhabiting different lakes.

A taxonomic revision of the genus Hydrocharis (Hydrocharitaceae) is presented with full descriptions, diagnoses, synonyms with typifications, distribution maps and illustrations and including information on ecology, floral biology, anatomy, embryology, chromosomes and variation with a rather extensive bibliography. Three well-defined and allopatric species are recognised: H. morsus-ranae L., W. and N. Eurasia and introduced in N. America; H. dubia (Blume) Backer, S. and E. Asia and Australia; H. chevalieri (De Wildeman) Dandy, Central Africa.

Electro-phoretically detectable isozyme variation was studied for 17 enzyme systems in several N American populations of the introduced aquatic plant Hydrocharis morsus-ranae and in two European populations. Twenty-nine loci were inferred from progeny, adult and turion enzyme banding patterns with 28 of these loci homozygous in all individuals studied. Malate dehydrogenase-1 (MDH-1) was the only locus which could be interpreted as multi-allelic and heterozygous. Twenty-seven of 76 seedlings assayed showed an age specific expression for an alcohol dehydrogenase locus (ADH-2) never seen in adults or turions. Since all adults sampled were phenotypically identical at all loci assayed, it is possible that only one isozyme genotype of this species is present in N America. European turion data further indicated that the populations studied were identical to N American plants sampled at all loci except EST. Therefore, although H. morsus-ranae is dioecious, outcrossing appears to involve substantial inbreeding. Connections between extensive inbreeding and the failure of effective sexual reproduction are considered.

Phytosociological species groups within the classes Lemnetea and Potametea are investigated on the basis of 3000 releves. The relations between species are calculated with the coefficient of Hamming and a % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Xdm2aaW% baaSqabeaacaqGYaaaaaaa!3885!\[\chi ^{\text{2}} \]. The results are presented in the form of a table with the species ordered in a linear sequence as well as in a plexus diagram. The 47 most frequent species are grouped into 4 clusters and the significance of these phyto-sociological species groups for the syntaxonomy of aquatic communities is discussed. Cluster 1 shows many high contingency values. It comprises the pleustophytic species of the Lemnetea. The isolated position of Utricularia vulgaris, the almost identical contingency profiles of Lemna minor and Spirodela polyrrhiza, the contrast between Lemna gibba versus Lemna trisulca, Riccia fluitans and Ricciocarpus natans, and the strong relation between Hydrocharis and Stratiotes are emphasized.

This study of seed and seedling morphology in the aquatic monocotyledon Hydrocharis morsus-ranae L. (Hydrocharitaceae) represents part of a continuing study of sexual reproduction in this species. Scanning electron microscope studies of the seeds showed them to have testas covered with hollow spiraliform tubercles. Germination occurs when the radicle and cotyledon of the embryo from the exalbuminous seed elongate, splitting the tuberculate testa. The buoyant embryo then rises to the surface with the first foliage leaves emerging from a highly modified cotyledonary sheath. This makes early growth in the seedling look strictly hypocotyledonary. Both the radicle and cotyledon discontinue growth by the two-leaf stage in the seedlings. The young seedlings undergo several growth phases. At first they look Lemna-like in habit and then, subsequently, very similar to germinating turions of the same species. Several methods are discussed to help distinguish between germinating turions and seedlings. During a subsequent field study of a H. morsus-ranae population, only two germinating seedlings were discovered. Several reasons for the absence of seedlings in this population are discussed.

Roots of water hyacinth (Eichhornia crassipes (Mart.) Soims.) and frogbit (Hydrocharis morsus-ranae L.) when grown In solution cultures adjusted to pH 3.5, 4.0, 5.0, 6.0, and 6.5 did not suffer decidedly adverse, direct effects from hydrogen ions except at extreme acidities represented by a pH value of less than 4. During cool weather the plants were able to grow at a somewhat higher concentration of hydrogen ions than was possible in the warm summer months. The boundary between good growth and toxicity was a narrow one. Extreme acidity, short of the critical point, inhibited the growth of the roots by decreasing cell division and cell elongation. In the roots investigated, cell division at pH 3.5 was reduced to one-half of the rate at pH 5.0 and this reduction accounted for three-quarters of the inhibition in the growth of the roots. When grown in a highly acid medium, root cells acquired a resistance to the hydrogen ions. Water hyacinth meristem cells from the highly acid media exhibited a pronounced resistance to hydrochloric acid. It is suggested that this increased resistance is due to the cells having acquired a greater impermeability to the acids. Determination of the pH of expressed root juices revealed that, although all of the saps were decidedly less acid than were the media in which the plants were grown, roots grown in an extremely acid medium had a slightly more acid sap than those grown in a less acid one. A comparison of rates of streaming and the action of protoplasts during plasmolysis indicated that extreme acidity in the growth medium increased the viscosity of the cytoplasm of root cells. No significant difference was noted in the osmotic pressure of the root cells from the different cultures. The absolute permeability of frogbit root hairs to thiourea, as calculated from the formula [Formula: see text], did not vary significantly from.0012 millimoles per square centimeter of surface per hour per molar concentration difference for plants grown within the range of pH 3.6 to pH 6.0.

The root cell plastids and their development were studied in seven genera of hydrophytes: Lemna, Nymphoides, Hydrocharis, Trapa, Eichhornia, Najas, and Hydrilla under the electron microscope.Roots of these hydrophytes with exception of Eichhornia appear slightly greenish and their plastids are composed of grana-lamellar structures. In some of the young plastids, the development of arranged vesicles into lamellar structures has been observed.In the plastids of Eichhdrnia root cells, no grana-lamellar structure has been observed.

Regular sequences of leaf and bud formation occur in several members of the Hydrocharitaceae, including Hydrocharis, in which buds are normally formed in the axil of every second leaf of the phyllotactic spiral. Leaf inception begins by periclinal divisions of the inner cells of the 2-layered tunica. Bud formation, which occurs in the apical meristem itself, immediately following the inception of the subtending leaf primordium, begins by divisions in various planes in the corpus, the 2 tunica layers remaining continuous throughout. The young bud meristem soon gives rise to a lateral bud, before leaf formation begins upon it. Because of these and other features, this species is one of considerable morphogenetic interest. Morphogenesis of the whole plant, and in particular the factors controlling the regular sequence of leaf and bud formation, have been and are being investigated experimentally. HYDROCHARIS morsus-ranae L. is a floating aquatic plant with a rosette of spirally arranged leaves and numerous pendent adventitious roots. During the summer months, in Europe, the plant produces long, leafless stolons which termillate in a rosette of leaves and themselves give rise to stolons of the second order; this pattern of growth is repeated in successive branches of higher order. A population of Hydrocharis thus consists of a mat of branching plants of some complexity, although, in fact, only a small proportion of the buds present actually form stolons. In autumn, the stolon apices form dormalnt winter buds, or turions, of some size and complexity; these sink to the bottom of the pond or canal and overwinter there. In the following spring the turions rise to the surface and expand to form new plants. The physiology of dormancy in turions, especially the effects of light and temperature, has already been extensively studied (Vegis, 1955), and their behavior on the renewal of growth, in various conditions, has been examined by the writer as a contributioni to whole-plant morphogenesis. The results will be reported in later papers. Although the morphology of Hydrocharis and related genera was closely examined some 60-100 years ago, these materials are still of considerable interest to students of morphogenesis. For example, as the earlier workers reported, in Hydrocharis buds are formed only in the axil of every second leaf of the rosette (Irmisch, 1859, 1865; Rohrbach, 1873). This observation, which has been confirmed in a short contemporary paper by Loiseau and Nougarede (1963) and by the present writer, is of both morphological and physiological interest from the standpoint of the factors determining 1 Received for publication August 12th, 1963. The author is greatly indebted to Professor C. W. Wardlaw for his helpful discussions of this work, and to Mr. G. Grange for taking the photographs. morphogenetic pattern. This interest is increased and extended by the further observation that, in several members of the Hydrocharitaceae, other cognate, but sometimes less regular, patterns occur. There are also interesting parallels with members of another family of aquatic plants, the Nymphaeaceae. The importance of studying by both analytical and experimental means the factors which control regular and less regular sequences of leaf and bud formation needs no emphasis. The present paper gives a short account of the origin and development of leaves and buds in Hydrocharis and will serve as a basis for accounts of experiments which are in preparation. MATERIALS AND METHODS-The material mainly consisted of turions collected from plants in a local canal and pond, and also of apices of growing stolons. Material was fixed in Craf III (Sass, 1940), dehydrated and embedded in paraffin wax using standard techniques, and stained with safranin, orange G, tannic acid and iron alum (Sharman, 1943). Material to be sectioned longitudinally was first partially dissected and observed under a stereoscopic microscope. Rectangular slices of the turion were then excised in such a way that the sections would pass along a known plane, and fixed and embedded. To facilitate comparison, all illustrations of longitudinal sections are presented with the incipient leaf primordium (and bud, where present) on the right of the shoot apex. Young leaf primordia are called P1, P2, P3 etc., P1 being the youngest visible primordium (Snow and Snow, 1931). MORPHOLOGY OF THE TURION-Two distichous, enveloping scale leaves are present on the outside of the turion. Within these the future foliage leaves occur, in spiral sequence, forming a com

During a quantitative study of the littoral zooplankton of a backwater, temperature as well as some chemical conditions have been measured at monthly intervals throughout two years. All three stations with different types of vegetation showed during the daytime steadily higher temperatures near the surface than did the openwater station. pH, oxygen and alkalinity showed a clear dependence on the photosynthetic and respiratory activity of plants. At the station with a concentration of leaves of Nuphar, Hydrocharis, Myriophyllum, and Ceratophyllum near the surface, a remarkable vertical stratification of temperature and chemical factors were observed.

Extension growth of the chlorophyll-containing roots of Hydrocharis morsusranae was inhibited by 0.5 p.p.m. of 3-(4-chlorophenyl)-1,1-dimethylurea (monuron) whereas concentrations close to the water saturation point of 230 p.p.m. were required to inhibit extension growth of the non-chlorophyll-containing attached roots of Zea mays and Phleum pratense and the detached roots of Pisum sativum.A total of 15–20 μg of monuron per gram fresh leaf applied through the cut petiole of detached primary leaves of Phaseolus vulgaris inhibited the increase of dry matter by 90% and suppressed transpiration 40–50%. Internal concentrations of 1–2 μg/g of monuron produced simultaneous enhancement of dry matter increase and of transpiration but concentrations of 5–10 μg/g produced a suppression of dry matter increase concurrently with an enhancement of transpiration. Age of leaf and the time of year in which the plants were grown altered the critical internal concentration levels required to affect dry matter increase and transpiration.Analysis of detached leaves treated with 15–20 μg/g monuron indicated a marked suppression of the formation of non-water-soluble carbohydrate, a slight suppression of the formation of water-soluble nitrogen, but little or no effect on water-soluble carbohydrate or on non-water-soluble nitrogen.In detached leaves o-phenanthroline, 3-phenyl-1,1-dimethylurea, and 3-(3,4-dichlorophenyl)-1,1-dimethylurea resembled monuron closely in symptom development and in their effect on dry matter production and transpiration. Iodoacetamide, 2,4-dinitrophenol, and 8-hydroxyquinoline each produced some effects similar to monuron but differed from it in certain respects; Thiourea, sodium diethyldithiocarbamate, sodium fluoracetate, ethyl-NN-diphenylcarbamate, and hydroxylamine hydrochloride were without noticeable effect.