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Stopping invasive species early, before they are introduced or before they have a chance to spread, is essential for effective invasive species management. With new plants introduced constantly through global trade and shifting their ranges due to climate change, proactive action to prevent invasions is more important than ever. But, before we can prevent invasions through policy, monitoring, and management, we need to know the identity of which species are invasive. Existing lists of invasive plants vary across political and jurisdictional boundaries, often rely on inconsistent knowledge of local experts, and may conflate nonnative with invasive. Here, we reviewed papers published from 1959 to 2020 to create a single consistently derived list of known invasive plants. We searched the Web of Science core collection for "articles" containing the keywords "invasi*" and "plant" within the categories "Ecology," "Environmental Sciences," "Biodiversity Conservation," and "Plant Sciences." We also reviewed papers cited in reviews of invasive plants (see Metadata S1, Class II, Section B). We read titles and abstracts to identify papers that focused on nonnative and invasive vascular plants and included in the database any nonnative plant taxon either explicitly termed invasive in the paper or implicitly defined as invasive through a description of abundance, spread and/or impact. For 2017-2020, we included only papers that described multiple invasive plants, which are much more likely to uncover novel taxa. For each paper, we retained the reported invasive taxon name, text defining invasiveness, bibliographic information, and the country or countries in the invaded range where the study took place. We used Catalogue of Life and the Plant Taxonomic Name Resolution Source to resolve the taxonomy of the invasive taxa and compiled a list of unique invasive plants described in one or more scientific papers. We extracted data from 5,893 papers and identified 3,008 unique taxa, including 2,842 species, 96 subspecies, 29 varieties, and 41 hybrids. Of these, 2,981 taxa were resolved, while 27 were unresolved. 42% of the total unique taxa were studied once in the database. This database provides a consistent, global assessment of nonnative, invasive plant taxa. We release these data into the public domain under a Creative Commons Zero license waiver (https://creativecommons.org/share-your-work/public-domain/cc0/). Individuals who use these data for publication may cite this data paper., (© 2021 The Authors. Ecology © 2021 The Ecological Society of America.)

Extreme weather events, considered to be the most destructive natural hazards connected with rapid climate changes in the temperate zone of Europe, necessitate swift adjustments to the selection of ornamental plants for cultivation in multi-stress urbanized areas, public greeneries, and gardens. Moreover, given the rising average air temperature and prolonged growing season, as well as the delay and shortening of the dormancy period, plant phenology is subject to significant alternations. Herbaceous plants fulfill most elements of ecosystem service, e.g., they may enhance biodiversity in climate-warming conditions and create a favorable environment for trees in cities. In this work, we consider the advantages and disadvantages of the dissemination or introduction of annuals and perennials. We draw attention to species rarely or never known to have been cultivated in Europe, which currently occupy hotspots with the highest biodiversity value, including (i) the Mediterranean Basin, (ii) the Caucasus, (iii) Irano-Anatolian, (iv), and the mountains of Central Asia. We emphasize the importance of protecting threatened taxa through safe ex situ cultivation. Ornamentals should be characterized not only by aesthetic values but also by their ability to adapt to environmental changes. However, bearing in mind that horticulture is an important source of invasive alien species, further research assessing the ecological threats and advantages should be conducted. [ABSTRACT FROM AUTHOR]

Two new alien species, Rudbeckia hirta and Oenothera glazioviana, were recorded for the first time in southeastern Kosovo along the banks of the Lepenci River. The localities, habitat types and population sizes of these species were studied. Twenty individuals of Rudbeckia hirta were found in a 50 m² area, indicating its early naturalisation. Oenothera glazioviana, Oenothera glazioviana, known for its high invasiveness, was recorded close to Rudbeckia hirta habitat. These findings suggest that the river acted as a pathway for the introduction of these alien species. Considering the invasive nature of Oenothera glazioviana, it threatens native biodiversity. This study highlights the importance of proactive monitoring and management strategies to reduce the impact of invasive species and protect natural habitats in Kosovo. [ABSTRACT FROM AUTHOR]

Terminology for the invasion status of alien species has typically relied either on ecological- or policy- based criteria, with the former emphasising species' ability to overcome ecological barriers and the latter on species' impacts. There remains no universal consensus about definitions of invasion. Without an agreement on definitions, it is difficult to combine data that comes from a range of sources. In Australia, information on plant invasions is provided by a collection of independent jurisdictions. This has led to inconsistencies in terminology used to describe species invasion status at the national level, impeding efficient management. In this paper, we review and discuss the steps taken to harmonise the different terminologies used across Australia's states and territories. We identified mismatches in definitions and records of invasion status for vascular plant taxa across different jurisdictions and propose prioritisation procedures to tackle these mismatches and to integrate information into a harmonised workflow at the national scale. This integration has made possible the creation of a standardised dataset at the Australian national scale (the Alien Flora of Australia). In Australia, having an integrated workflow for referring to and monitoring alien flora will aid early warning and prevent species introduction, facilitate decision-making and aid biosecurity measures. [ABSTRACT FROM AUTHOR]

This paper presents a preliminary checklist of the invasive alien plant species (IAPS) in eastern Kosovo. This list was compiled based on a literature review and field surveys in the period between 2020-2022. The list includes 20 plant taxa with information on taxonomic affiliation (Family), life form, native range and type of habitat(s) they invaded. Most species belong to Asteraceae family, followed by Fabaceae and Balsaminaceae. Therophytes are the predominant life form. There are two genera, each with two species: Erigeron L. (Erigeron annuus (L.) Desf., Erigeron canadensis L.) and Impatiens Riv. ex L. (Impatiens balfourii Hook.f. and Impatiens glandulifera Royle), while others are represented by only one species. The majority of IAPS in the eastern region of Kosovo are from North, Central and South America (65%), followed by Asia (30%) and with only one species from Africa (5%). The habitats most heavily colonized by IAPS are the areas along roads, waste places, riverbanks and cultivated areas. [ABSTRACT FROM AUTHOR]

Cities are often hotspots for biological invasions, showing much higher percentages of alien species than non-urbanized settings. The reasons are multiple and are mostly related to two main factors: their heterogeneous, highly disturbed habitats and their many gateways that allow alien species introduction (e.g., airports, roads, train stations, or gardens). In addition to being a sink of biological invasions, cities can also be a source of the spread of alien species into surrounding landscapes, which adds further complexity to this issue. Herein, we are presenting the results of a five-year survey of the alien flora of Montjuïc, the largest urban hill in Barcelona (Spain). In just about 3.4 km2, we recorded up to 247 alien plant taxa, a figure much higher than those of many other Mediterranean cities and which clearly points to the role of Montjuïc as a hotspot for alien plants. The comparison with the alien flora of its surrounding region (coastal Catalonia) suggests that the alien flora of Montjuïc would have become enriched through many immigration episodes from close geographic areas. The hill, however, would have also acted as a source of the spread of alien plants, and indeed, some species have not been detected yet beyond the confines of Montjuïc. This study aims to be a key tool to ensure early detection and also to develop appropriate management and/or eradication actions. [ABSTRACT FROM AUTHOR]

Alien species represent one of the causes of biodiversity loss, both in natural and anthropic environments. This study contributes to the assessment of alien species impact on Western Po Plain rice field cultivations, referring to different agricultural management practices and ecological traits. Flora and vegetation were studied (the latter through the phytosociological method), and α-biodiversity was estimated through Shannon and Simpson Indices. Results highlighted a significant floristic contingent depletion and increase in therophyte and alien components, compared to pre-existing studies (1950s); higher α-biodiversity levels in organic farms, compared to conventional farms, but also a higher invasive alien species percentage. The high deterioration of the territorial–landscape context appears to play a major role in shaping these patterns. Some of these alien species are particularly aggressive (e.g., Murdannia keisak), as confirmed by two experimental rice field plots which were left unharvested, continuously flooded, making it possible to assess the competitiveness between weed species. The detected weed vegetation is attributed to the Oryzo sativae-Echinochloetum cruris-galli association, already described for Southern Europe, with two different ecological and floristic variants. Future studies, by including other sites and framing their territorial–landscape context, may further complement this overview on the alien species distribution and behavior in rice fields, hence facilitating their strategic management. [ABSTRACT FROM AUTHOR]

During field investigations in Morocco, two new alien species, Amaranthus spinosus (Amaranthaceae) and Cardamine occulta (Brassicaceae), were discovered as new to the country. Additionally, C. occulta seems to be the first record for continental Africa. The distribution and ecology of these species are discussed. [ABSTRACT FROM AUTHOR]

Lupinus gredensis is recorded as a new species for the adventive flora of Bulgaria. It was discovered in the Eastern Rhodope Mountains (Ivaylovgrad and Krumovgrad districts). The species grows in open dry grasslands and roadside ruderal vegetation, on siliceous and serpentine substrates. Its most distinctive feature is the change of the flower color, which is cream to off-white at first, and subsequently, in the ageing flowers of the same inflorescence, turning lilac to mauve. Lupinus gredensis is an endemic taxon restricted to the Iberian Peninsula. So far, it has been known as an alien species only in Greece. Revisiting the available records of L. hispanicus from Turkey has revealed that they also belong to L. gredensis. In Bulgaria, the earliest finding of L. gredensis, erroneously identified as L. luteus, dates back to 2003. The aim of the present article is to report L. gredensis as an addition to the Bulgarian alien flora and to provide data on the main distinguishing characters of the species and its distribution in Bulgaria and Turkey. [ABSTRACT FROM AUTHOR]

Relative to other vascular plants, ferns have been overlooked with respect to the potential for nonnatives to spread into natural areas and potentially displace native species. An unusual site in the Piedmont of northeast Georgia was found to harbor two species of nonnative ferns that have clearly become naturalized. A third species at the site represents the appearance in a natural setting of another nonnative fern species whose cultivars and hybrids are being more widely planted as ornamentals. Examination of herbarium specimens from Georgia and the Southeastern United States clarified the status of some earlier records and some overlooked records, based on misidentifications or questionable status as naturalized. The species involved (Arachniodes simplicior, Polystichum polyblepharum, and Anisocampium niponicum (=Athyrium niponicum)) are all introductions from temperate regions in East Asia and probably represent escapes from cultivation via spores. The appearance of these species in natural communities raises questions about their potential to spread farther and to become pests by crowding out native flora. The invasive potential of these three species and five other species discussed in a previous paper is evaluated based on field observations as well as information about their status as an epiphyte or ground dweller, reproductive plasticity, ecological requirements, and popularity as horticultural ornamentals. [ABSTRACT FROM AUTHOR]

Xanthium is a taxonomically intricate genus of the sunflower family (Asteraceae). In Italy, two species of Xanthium sect. Xanthium are present: the native X. strumarium and then introduced X. orientale. In this study, we assess changes in relative frequency of these two species in Italy based on herbarium records. Based on our analyses, we could observe a strong decline of the native X. strumarium in Italy, started approximately one hundred years ago. Since then, this species has become extremely rare and more effort should be spent to investigate its actual distribution range and potential extinction risk in Italy. This study also demonstrates the importance of herbaria to address questions regarding the dynamics in relative frequency and distribution of competing native and introduced species. [ABSTRACT FROM AUTHOR]

We present the second edition of the checklist of alien and cryptogenic bryophytes (Bryophyta) in Austria. In total, four alien bryophyte species are reported, of which three are established, and for one it is unknown if it is casual or established. In addition, four cryptogenic species (i.e. species that are likely alien, but their biogeographic status is uncertain) are included, of which one is casual and one is extinct. In comparison with the first checklist of alien bryophyte species for Austria published in 2002, the number of alien or cryptogenic bryophytes has risen by four species. Most alien or cryptogenic bryophytes in Austria are native to continents of the Southern Hemisphere. Most invaded ecosytems in Austria are man-made habitats, fields, forests and mires. One species (Campylopus introflexus) is assumed to locally cause negative environmental impacts. [ABSTRACT FROM AUTHOR]

Recent field work by the authors on the island of Gran Canaria (Canary Islands, Spain) yielded new interesting records of non-native species. Seven species, i.e. Centaurea sulphurea, Clematis flammula, Fallopia baldschuanica, Fraxinus angustifolia, Melilotus officinalis, Saponaria officinalis, and Searsia lancea have not been recorded before from the Canary Islands, whereas 13 species (Bellis perennis, Centaurea diluta, Chlorophytum comosum, Chondrilla juncea, Cyperus papyrus, Delphinium ajacis, Helianthus annuus, Lonicera japonica, Lupinus pilosus, Montanoa bipinnatifida, Ornithogalum arabicum, Trifolium cernuum, and Wigandia caracasana) are reported for the first time from Gran Canaria. The actual presence of five further species (Chenopodium vulvaria, Fallopia convolvulus, Kalanchoe daigremontiana, Paspalum dilatatum, and Volutaria tubuliflora) - all considered doubtful, recently discovered or with only historical occurrences in Gran Canaria - is confirmed. Chorological and ecological details are presented for these species and their invasion status is assessed. Many of them are reputed weeds, either agriculturally or environmentally. [ABSTRACT FROM AUTHOR]

Kozara National Park is exposed to different anthropogenic influences even though it is categorized as IUCN Category II. In this study, we investigated, identified and mapped invasive flora and their impact on the native plant communities. During summer 2018, the fieldwork was conducted at 6 locations using the Braun-Blanquet method for the investigation of plant communities. The total of 13 invasive alien species (IAS) have been detected. Most of the IAS belong to the Asteraceae family, originating from North America (76.92%). The most abundant life forms were therophytes and geophytes found in Artemisietalia communities. Conclusively, the IAS are widespread in the examined area, particularly in the parts of the park designated for tourist recreational activities. [ABSTRACT FROM AUTHOR]

Due to the relevance of protected areas to the conservation of native biota, the magnitude of invasions and threats posed by alien plants are currently important issues for the preservation of these areas. The paper summarises data on invasive alien plant species presence in the most valuable protected areas in Poland, i.e. national parks (NPs). We investigated the distribution of invasive alien plant species and management attempts concerning those species. We analysed data obtained from 23 national parks originating from published and unpublished sources. Invasive plants were present in all protected areas analysed, from two to 42 species in a particular national park, and 68 in total. The most widely distributed species were: Impatiens parviflora (present in 19 NPs), I. glandulifera (17), Solidago gigantea (17), Reynoutria japonica (17), and Robinia pseudoacacia (16). The conducted analyses showed that the number of invasive species decreased with the higher altitude (asl) of the national park. The most often managed species were Impatiens glandulifera (being removed in seven NPs), I. parviflora (six), Padus serotina (four) and Quercus rubra (four). In the majority of NPs, control activities are limited to small areas and singular species, thus having an incidental character. Only in five objects (Białowieża NP, Biebrza NP, Kampinos NP, Tuchola NP, Wigry NP), management has been focused on several species. We conclude that a lack of comprehensive management of invasive plant species in the majority of national parks currently limits the effectiveness of IAS (invasive alien species) eradication. Exchange of expertise among protected areas, documenting best practice examples, synthesising lessons learnt in IAS management, as well as the development of minimum standards for invasive plants surveillance and management are pivotal. [ABSTRACT FROM AUTHOR]

In this paper, we provide an overview of the distribution and invasive status of non-native species in the Italian flora across its administrative regions, biogeographic regions and main land use types, and a synthesis of current knowledge on the threats they pose within the country. The information on non-native plant species collected during the project “A survey of the non-native Italian flora” was used to compile comprehensive regional and national databases. The number of non-native species within a given administrative region increases in proportion to its size, resident population density and latitude, reaching the highest values in the intensively cultivated, heavily industrialized and urbanized Po Plain in northern Italy. The number of casual species is positively correlated with the number of yearly visitors in each region and negatively correlated with the proportion of mountainous terrain within the region. If compared with the Continental and Mediterranean biogeographic regions, the Alpine region yields the lowest number of non-native species and lowest proportion of casual species. The number and density of introduced species is highest in artificial land use types, particularly in urban areas. A negative impact is reported to be exerted by 203 species, most of which are agricultural weeds. [ABSTRACT FROM AUTHOR]

A geographic and taxonomic overview of the non-indigenous plant species of Europe, based on the 'Flora Europaea' is given. The flora of Europe includes 1568 species which have either expanded their ranges within Europe under human influence (naturalized European species) or are of non-European origin (exotic species). The latter group consists of 580 species (37%) which form a diverse group in terms of their taxonomic composition and geographic origin. The exotics are represented by 113 families, of which the Compositae, Rosaceae and Gramineae are most important. The ratio of species to families is low. Most exotic species in Europe originate from the Americas and Asia. Countries of southern Europe have a higher relative number of exotics in their non-native flora than northern ones. The species-range size distribution differs between naturalized European and exotic species; the latter are on average more widespread than the naturalized. [ABSTRACT FROM AUTHOR]