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In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions, and status changes for Italy or for Italian administrative regions. Furthermore, three new combinations are proposed. Nomenclatural and distribution updates published elsewhere are provided as Suppl. material 1.

Utricularia (bladderwort) trap contents have frequently been used to define its diet, but there is a scarcity of information on prey availability. Yet making comparisons between trap contents and outside communities could help define feeding strategies of these fascinating carnivorous plants. This study focuses on U. australis, the most common aquatic bladderwort in central Italy, with data of inside- and outside-trap communities from 23 sites. The feeding strategy of U. australis is highly dependent on prey availability and size; the prey has to be large enough to stimulate trap triggering, yet small enough to be taken up through the trap door unimpeded. In addition, the prey has to be moderately motile but not dispersive. The trap contents were generally a mixture of species taken up by active and spontaneous trap firing. Stimulation of a heavy epiphytic growth by Utricularia resulted in higher entrapment of epiphyte-grazing taxa resulting in a positive feedback loop. The comparative data here also suggest that prey digestion is a rapid enough process that keeps up with the seasonal succession of the outside community. The trapped community (or the diet) of U. australis seems to derive by the contribution of all these factors.

Life cycle of the aquatic moth Cataclysta lemnata (Lepidoptera: Crambidae) was studied in laboratory conditions to obtain a basic biological knowledge useful for predicting the possible success of the herbivorous larvae of this insect as potential control agents in limiting the spread of the invasive American duckweed Lemna minuta (Alismatales: Araceae) in Italy. The multivoltinism of C. lemnata, as well as the high overall emergence from the pupal stage (85%), the high success in mating among the formed couples (>90%), and the high number of larvae born from each egg laying (on average 310 individuals), suggest that the insect can be successfully bred in the laboratory for the purposes of an augmentative biological control. Under experimental conditions, larvae developed in 23 days (through six larval instars, distinguishable by cephalic capsule dimensions) and pupae in 10, with no difference in duration between females and males. The larval phase resulted longer than the adult one (23 vs 10 days), therefore it can be considered the most suitable stage for releasing the insect in field for biocontrol purposes. Indeed, the larvae having a herbivorous diet might consume large amount of the invasive plant, contrarily to the adult phase which is focused exclusively on reproduction. The results emerged not only allow to contribute to the knowledge on aquatic lepidoptera that are scarcely known, but also support the effectiveness of a possible protocol for an augmentative biological control of the invasive alien duckweed L. minuta.

Phytoremediation potential of duckweeds (Lemna minuta, Lemna minor) to remove nutrients from simulated wastewater was analyzed. In two separate experiments, the two species were grown for 28days in waters enriched with nitrate and phosphate to simulate nutrient concentrations of domestic wastewater. Water physicalandchemical measurements (temperature, pH, conductivity, oxygen) and plant physiological and biochemical analysis (biomass, relative growth rate–RGR, nutrient and chlorophyll contents, peroxidative damage, bioconcentration factor–BCF) were made to test and compare the phytoremediation capacity of the two Lemna species. L. minuta biomass increased almost tenfold during the time-course of the treatment resulting in a doubling of the mat thickness and a RGR of 0.083 ± 0.001g/gday. Maximum frond content of phosphate was reached by day 21 (increase over 165%) and nitrate by day 7 (10%). According to the BCF results (BCF > 1000), L. minuta was a hyperaccumulator for both nutrients. On the other hand, L. minor biomass and mat thickness decreased continuously during incubation (RGR = − 0.039 ± 0.004g/gday). In L. minor fronds, phosphate content increased until day 14, after which there was a decrease until the end of the incubation. Frond nitrate content significantly decreased by day 7, but then remained relatively constant until the end of the experiment. L. minor proved to be hyperaccumulator for phosphates, but not for nitrates. Results indicated L. minuta has a greater potential than L. minor to remove both nutrients by bioaccumulation, especially phosphates, demonstrated also by better physiological and biochemical responses. However, during the incubation, the chlorophyll content of L. minuta mat did continuously decrease and peroxidative damage had increased until day 14, indicating that the system was under some kind of stress. Strategies to avoid this stress were discussed.

The free-floating American duckweed, Lemna minuta, is an invasive species now widespread in Europe. Yet, its impact on freshwater ecosystems has been poorly investigated. In this study, the effects of thepresence of this invasive duckweedon water quality, and aquatic plant and invertebrate communities were evaluated in sites in Central Italy. Water chemical and physical factors and community descriptors were analyzed to identify these effects. Surveys were carried out across 17 paired aquatic sites. Site pairs were similar in microclimate, hydrogeology and water quality, but differed in relation to the presence/absence of L. minuta floatingmats. In sites with mats, light and dissolved oxygen in water were negatively correlated with increasing mat coverage and thickness. The limited light and hypoxic conditions under mats inhibited plant growth and had a selective impact on the invertebrate community. Sites with L. minutahad aquatic communities with a lower plant taxa richness and a contrasting composition, compared with those in sites without. At sites with matssome plants were unaffected, but the majority of plant taxa documented at sites without Lemna were no present at sites with Lemna or were very rare (macroalgae, submerged rhizophytes). As for invertebrates, hypoxic-tolerant taxa dominated under mats (Ostracoda, Copepoda, Isopoda), whilst those more sensitive to oxygen depletion, or obligate herbivores, or those with a winged stage or swimming on water surface, were rare or absent (Ephemeroptera, Amphipoda, Chironomus, Notonecta). Lemna minuta mats presencewas associated with alterations in the underlying aquatic ecosystem, severely threatening the conservation of these habitats. Active management strategies, including spread-prevention techniques, or mechanical removal combined with biological control, are required to conserve these habitats.

This paper reviews the current state-of-the-art, limitations, critical issues, and new directions in freshwater plant ecotoxicology. We selected peer-reviewed studies using relevant databases and for each (1) publication year, (2) test plant species, (3) reference plant group (microalgae, macroalgae, bryophytes, pteridophytes, flowering plants), (4) toxicant tested (heavy metal, pharmaceutical product, hydrocarbon, pesticide, surfactant, plastic), (5) experiment site (laboratory, field), and (6) toxicant exposure duration. Although aquatic plant organisms play a key role in the functioning of freshwater ecosystems, mainly linked to their primary productivity, their use as biological models in ecotoxicological tests was limited if compared to animals. Also, toxicant effects on freshwater plants were scarcely investigated and limited to studies on microalgae (80%), or only to a certain number of recurrent species (Pseudokirchneriella subcapitata, Chlorella vulgaris, Lemna minor, Myriophyllum spicatum). The most widely tested toxicants on plants were heavy metals (74%), followed by pharmaceutical products and hydrocarbons (7%), while the most commonly utilized endpoints in tests were plant growth inhibition, variations in dry or fresh weight, morpho-structural alterations, chlorosis, and/or necrosis. The main critical issues emerged from plant-based ecotoxicological tests were the narrow range of species and endpoints considered, the lack of environmental relevance, the excessively short exposure times, and the culture media potentially reacting with toxicants. Proposals to overcome these issues are discussed. Supplementary Information The online version of this article (10.1007/s11356-020-11496-3) contains supplementary material, which is available to authorized users.

The American duckweed Lemna minuta is invasive in freshwater habitats across much of Europe, often causing serious ecological impacts. To date, few studies have addressed how to halt its expansion. However, encouraging empirical evidence of L. minuta control by the aquatic herbivorous larvae of the insect Cataclysta lemnata is emerging. To better understand the biocontrol capacity of C. lemnata, information on overlap in the phenology and the growth conditions in nature of both species is fundamental. In this study, L. minuta and C. lemnata populations were analyzed in the field to define (i) their phenological features, (ii) the main environmental characteristics where the two species occur, and (iii) any overlap or difference in phenology and ecological requirements. The seasonal occurrence of the two species and environmental data were collected from 31 wetlands in central Italy. The two species showed a large phenological overlap and ecological similarities. Populations of L. minuta and C. lemnata were found all year long, although abundances were greater in spring and summer. Both species preferred waters that were shallow, circumneutral, with moderately high conductivity and trophic level and with low dissolved oxygen. The phenology and ecology of the two species were shown to be compatible, suggesting the insect could be released in natural sites invaded by the alien L. minuta where could act as potential biocontrol agent of it.

Since effects of alien invasive free-floating plants can be relevant in aquatic ecosystems, we investigated the non-native Lemna minuta impact on four aquatic animal groups: Hydra vulgaris (Coelenterates), Asellus aquaticus (Arthropods), Gambusia affinis (Fish), Bufo bufo tadpoles (Amphibians). An indoor experiment was conducted keeping animals in water held in tanks with L. minuta mats of 0.5 (WI1), 1.5cm thick (WI2) and without mats (WOU). Water parameters (DO, DO%, pH) and animal responses (survival rate, vitality) were measured every 48 h (0–288 h). Treatments with mats showed significant impacts on animals which were more severe with increasing mat thickness. Strong decreasing of oxygen and pH associated with mat occurrence had a large impact on animals. In WI2 all individuals died within 144 h (H. vulgaris, B. bufo within 96h), while in WI1 there was a higher survival rate and vitality (excluding B. bufo died within 96 h) and in WOU no deaths. This evidence suggests L. minuta thick mats (1.5cm) could have a high impact on animal biodiversity, especially reducing oxygenation level in aquatic ecosystem.

Utricularia australis is an aquatic rootless carnivorous plant that takes up nutrients through shoots or from trapped prey digested in its bladders. As the information on the ecology of this species is scarce, the main environmental factors which favour or limit its growth were analysed. Habitat characterization was carried out on 23 aquatic sites in Central Italy where U. australis occurred. Diverse water chemical and physical factors and aquatic plant dominants were sampled and compared to Utricularia coverage. Species response curves with respect to each analysed ecological factor were elaborated. Despite the large environmental variation among sites, U. australis did show some ecological preferences. Optimal growth of Utricularia was associated with sunny sites (~ 1500µmol photon m−2s−1) and shallow waters (< 20cm) that were warm (~ 26°C), alkaline (pH 8.3 median value), with moderate-high conductivity (700µScm−1) and with low aquatic inorganic phosphorus (< 10µgL−1) but higher nitrogen (800–1600µgL−1). Dissolved and particulate organic nutrients (mainly phosphorus) were highly important in determining U. australis ecology and its distribution. The knowing of theecological preferences ofU. australis, a plant that is becoming increasingly rare in Central Italy, could be very useful to identify and protect its habitats or to identify new potential sites and to avoid further population losses.

Alien plant invasion is a serious threat for biodiversity conservation. Most theories on the mechanisms regulating the expansion of an alien species, agree that herbivory is one of the main factors affecting the success or failure of these species. One worrying example in Europe is the American duckweed Lemna minuta that, since its arrival in the 1940s, has become wide spread throughout many countries. This study focused on determining and quantifying the herbivorous nature of the larvae of the moth Cataclysta lemnata (native to Europe) with regards to L. minuta. On the premise that, if a native herbivore feeds on an alien plant species, it could help to contain its expansion. We tested the effectiveness of larvae at three different instars in consuming L. minuta under laboratory conditions. Laval preference for the alien L. minuta and the native L. minor was determined by quantifying the removal of monolayer mats of these two duckweeds. Firstly, we found that C. lemnata larvae was able to use L. minuta as a trophic resource and also to build protective cases. Moreover, they feed effectively, and seemingly without preference, on both the native and the alien species, contrary to the Enemy Release Hypothesis, which assumes that native consumers are better adapted to consume native species than alien ones. In addition, C. lemnata late-instar larvae were more efficient in Lemna consumption. This study suggests that where C. lemnata is a native herbivore the spread of L. minuta could be effectively contained.

We constructed a new ecotoxicological tool to test for the presence of teratogens in rivers by exploiting the regenerative capabilities of Hydra vulgaris because using living organisms is considered good practice in environmental monitoring for detecting detrimental pressures. Outputs on the Hydra assay were integrated with two biotic indices based on benthic invertebrates and macrophytes to evaluate whether the assay acts as a tool for detecting generalised freshwater conditions or as a biological test model revealing only the effects of dissolved teratogens. Several hypostomae of H. vulgaris were reared in waters collected in diverse southern central Latium rivers, where physiochemical descriptors were surveyed for environmental characterisation. The regeneration rate and amount of aberrations were evaluated to obtain a teratogenic risk index (TRI) score and then compared with the control. TRI calculations showed 4 sites (18.18%) in Class I (no risk), 15 sites (68.18%) in Class II (low risk), 2 sites (9.09%) in Class III (moderate risk) and 1 site (4.55%) in Class IV (high risk). No Class V sites (very high risk) were found. No significant correlations emerged among physicochemical parameters (except for PO43–), environmental descriptors, Simpson diversity indices and biotic indices and the TRI. These results promote an integrated approach to improving links between biological and ecological responses to anthropogenic impacts.

""The flora of the archaeological area of Maxentius’s villa (Rome) was tested as bioindicator of buried remains of masonry and pavements. A total of 53 floristic surveys provided the occurrence of each. species in the sample units, as well as some their phenological features. The data were elaborated through multivariate statistical analysis in order to assess floristic affinity\\\/differences among sample units, and to define their ecological characteristics. The fuzzy set methodology was applied to evaluate relation between floristic richness, plant cover and soil depth. Results show that the buried remains of stonework create a discontinuity in the ground, influencing the flora growing above it. This phenomenon. may give rise to differential presence of some species (e.g., Cota tinctoria, Trifolium scabrum ssp. scabrum. on thin soil; Ranunculus bulbosus, Trifolium pratense on deeper soil), but will not have such a great effect on floristic richness. The bioindication of this phenomenon also occurs through phenological irregularities in single specimens and changes in plant cover. Nevertheless other environmental factors (soil moisture\\\/aridity, trampling, enrichment of nitrogen, cutting, ground depression), can interfere with the use of plants as bioindicators in archaeological prospection. It is therefore necessary to consider other environmental factors influencing each site when using plants as bioindicators in the archaeological prospection.""