WE have here a comprehensive work embodying the results of a ten years' study of water plants, and dealing in a very practical fashion with the mass of literature that has grown up around the subject. As a book of authority on aquatic plants, it will be ranked with Schenck's work of a generation ago, and it would not receive its due if we did not add that it worthily holds the place. But we must not forget that other industrious investigators have in the meantime filled the gap. Prominent among them are Gluck, Goebel, Henslow, Pond, Sargant, Sauvageau, Willis, and many others. Since Schenck's time, however, new points of view have arisen, and new methods have been in use by numerous inquirers of both sexes, all keen in their desire to take a part in the new era of research. Water Plants: A Study of Aquatic Angiosperms. By Dr. Agnes Arber. Pp. xvi + 436. (Cambridge: At the University Press, 1920.) Price 31s. 6d. net.

Water Plants: A Study of Aquatic Angiosperms

Polska Czerwona Ksiega Roslin

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.

Changes in growth rate and macroelement and trace element accumulation in Hydrocharis morsus-ranae L. during the growing season in relation to environmental contamination

Ценокомплекс и экологические особенности Hydrilla verticillata (L. f.) Royle (Hydrocharitaceae) в Северной Евразии

Invasions are a threat to biodiversity because non-native species are generally more competitive than native species. Hydrilla verticillata is an invasive macrophyte that causes concern in many regions. We used field surveys and an experiment to test the hypothesis that H. verticillata colonization is negatively affected by a native competitor and positively affected by propagule pressure. We used data obtained in the field (a reservoir) to test whether H. verticillata was able to invade sites colonized by the native submerged macrophyte Helanthium tenellum. Then, we developed an outdoor experiment using H. tenellum as a competitor at different levels of H. verticillata propagule pressure. The field surveys indicated that H. verticillata invaded sites colonized by H. tenellum. Furthermore, our experiments showed that propagule pressure was effective in increasing H. verticillata colonization, while the presence of the native species was not enough to prevent early H. verticillata colonization, even at the lowest propagule pressure. We conclude that submerged macrophytes with creeping life forms, such as H. tenellum, do not provide biotic resistance to H. verticillata colonization independent of propagule pressure. These results are of concern because there are many important aquatic environments in Brazil that are colonized by creeping life forms macrophytes.

A native species does not prevent the colonization success of an introduced submerged macrophyte, even at low propagule pressure

Efremov, A.; Bolotova, Ya.; Mesterhazy, A., and Toma, C., 2018. Features of distribution of Hydrilla verticillata (L. fil.) Royle (Hydrocharitaceae) in North Eurasia. An assessment of Hydrilla verticillata (Hydrocharitaceae) distribution was made, with the involvement of a wide range of data (herbarium collections, Web resources, literature sources, and authors' observations), covering the period 1811–2016. It is shown that Hydrilla is a plurizonal macrothermal semicosmopolite species with many disjunctions in the geographical range. In the 20th century, H. verticillata expanded its secondary range significantly, primarily in North and South America (neocosmopolite). Within the primary range, in connection with high economic activities and development of transport, new invasion localities have appeared. For the European continent, H. verticillata should be considered a limitedly spreading naturalized neophyte (with the northern border at 55–56° N). In Northern Asia, H. verticillata can probably b...

https://bioone.org/journals/journal-of-coastal-research/volume-34/issue-3/JCOASTRES-D-17-00072.1/Features-of-Distribution-of-Hydrilla-verticillata-L-fil-Royle-Hydrocharitaceae/10.2112/JCOASTRES-D-17-00072.1.pdf

Features of Distribution of Hydrilla verticillata (L. fil.) Royle (Hydrocharitaceae) in North Eurasia

The aim of the research was to establish the density of specimens and shoots as well as the reproductive effort of Hydrocharis morsus-ranae during the whole vegetative period in a Polish oxbow lake The following specimen features were examined: plant diameter, total length, the number of buds, flowers, young fruit, ripe fruit, turions and leaves and also dry total mass, vegetative mass, generative mass, the bud mass, the flower mass, young fruit mass and ripe fruit mass The density of Hydrocharis morsus-ranae specimens per square metre ranged from 10 to 170 while the density of shoots ranged from 10 to 545 From one square metre overgrown with Hydrocharis morsus-ranae, a maximum of 389 turions, 50 fruit and 4000 seeds are produced The maximum of reproductive effort is 978% of vegetative mass and 22% of generative mass in September 2010 The factors which best explain changeability of the Hydrocharis morsus- ranae population in time are the length and the diameter of the specimens in the population Fruiting of Hydrocharis morsus-ranae in Poland is higher than in Canada, where it is an invasive taxon Hydrocharis morsus-ranae is well adapted to the environment in oxbow lakes of the River Vistula and represents the S-R strategy

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Reproduction of Hydrocharis morsus-ranae taxa in an oxbow lake of the River Vistula

Hydrilla verticillata (L. f.) Royle is a hydatophyte with a disjunctive semicosmopolite range playing a significant role in the functioning of aquatic ecosystems. The structure of the coenocompleх of the species in northern Eurasia includes 19 associations belonging to 17 formations of the freshwater macrophyte vegetation. Ninety-one species of hydromacrophytes have been recorded as part of the phytocoenosis with the participation of H. verticillata. Associations Hydrilla verticillata (Northern Eurasia) and Nymphaea candida— Ceratophyllum demersum + Hydrilla verticillata (Eastern Europe and Western and Central Siberia) have the widest geographical range. This paper describes the tolerance limits of H. verticillata to major abiotic factors: type of bottom soil, flow rate, trophicity, saprobity, alluviality, and content of main ions of dissolved salts and soluble forms of heavy metals in the water. In environmental terms, H. verticillata should be regarded as a freshwater alkaliphylic oligo-mesotrophic oligo-β-mesosaprobic mesoalluvialitic psammopelophyt.

Coenocompleх and Ecological Features of Hydrilla verticillata (L. f.) Royle (Hydrocharitaceae) in Northern Eurasia

Ecology of Stratiotes aloides L. (Hydrocharitaceae) in Eurasia

Research was carried out on fruits and seeds of Nymphaea and Nuphar taxa collected from Poland, Latvia and Estonia. The aim of the research was to establish diagnostic features which could enable identification of the examined taxa on the basis of the fruit and seed structure and creating a key to identify them. The examined organs were observed through an optic microscope and scanning electron microscope (SEM). New diagnostic features were discovered: spotting of fresh pericarp, the range of the fruit shape coefficient, the colour of the rays in the fruit stigma disc, the thickness of the seed testa, ribs in the seeds, and occurrence of the "puzzle shaped" cells on the surface of the testa. The discovered features were used in the taxonomic characteristics.

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Cezary Toma

Papers

Features of Distribution of Hydrilla verticillata (L. fil.) Royle (Hydrocharitaceae) in North Eurasia

Reproduction of Hydrocharis morsus-ranae taxa in an oxbow lake of the River Vistula

Coenocompleх and Ecological Features of Hydrilla verticillata (L. f.) Royle (Hydrocharitaceae) in Northern Eurasia

Ecology of Stratiotes aloides L. (Hydrocharitaceae) in Eurasia

Taxonomic features of fruits and seeds of Nymphaea and Nuphar taxa of the Southern Baltic region