New Alien Plant Taxa for Italy and Europe: An Update

Despite the wide amount of scientific contributions published on alien plant species, their diffusion dynamics, and their interactions with native taxa, it is increasingly difficult to slow down their spreading and their negative impact on habitats. Last recent years, in fact, a sharp rise in the number of new alien plant taxa introduced in Italy and Europe has been recorded. The aim of this work is to investigate most of the Italian territory in order to verify whether this alarming trend is still underway. Specimen collections and/or observations of alien plants have been performed in as many as 12 Italian regions. All the collected specimens are stored in public or private herbaria. Taxa have been identified according to the literature from the countries of origin of the investigated taxa, while the nomenclature followed the current international references. Updates on 106 taxa are reported. In particular, among 117 new records, 89 are first records, 27 are changes to status and there is 1 extinction. Seven new taxa for Italian alien flora are reported, two of which are new to Europe. The administrative regions with the highest number of records are Calabria (48), Sardegna (17) and Sicilia (15). Five of the surveyed taxa, for the first time, have been considered invasive aliens to Italian territory. The unfrequent amount of original results provided by this work, over the simple importance of data itself, proves how floristic investigation, still today, represents one of the most effective tools in broadening the current knowledge about alien taxa and their dynamics.


Introduction
The issue of alien plant invasions, while slowly gaining increasing global resonance, already has multiple significant impacts on ecosystems and mankind's activities [1,2].One crucial aspect of this worldwide phenomenon is represented by the correct identification and mapping of alien species occurring in each specific geographic area.Recent research has contributed to a better understanding of the dynamics of alien plant spreading [3], but during recent years, there has been a remarkable growth in studies on alien flora in many countries being performed, even those where, until now, little attention has been paid to this issue with possible negative consequences [4,5].The most recent scientific literature [6] emphasized the urgency of understanding not merely the occurrence of alien plant taxa, but also the possible interactions with native flora.The integrated approach to alien plant taxa management, also highlighted by recent contributions on alien flora in Calabria [7], reveals the need for evidence-based strategies to mitigate negative impacts and promote sustainable coexistence between native and allochthonous species.
Although Mediterranean basin habitats are considered quite resistant to plant species invasion [8], the phenomenon is, however, gradually increasing [9].While a general pattern in the features of alien flora invading climatically similar regions is lacking, because largely they are dependent on local conditions [10], it is clear that climate change and invasive alien species increasingly threaten the Mediterranean seagrass communities [11].In freshwater ecosystems, native species proved to be more susceptible to increased invasion of submerged macrophytes and eutrophication [12].However, invasive alien plant taxa also establish in almost all types of terrestrial environments [13], often determining important ecosystem modification [14][15][16].Although not all introduced plants become invasive [17,18], the ability to become invasive should not be underestimated, both for casual and naturalized alien taxa [19].Alien taxa are often introduced into urban green spaces, having more advantages than disadvantages compared to native species [20].
The overall aim of this study is to expand knowledge of the Italian allochthonous vascular flora.The specific objectives of this research are as follows: (a) To report new taxa for Italy and Europe.(b) To update the distribution of already known taxa and their occurrence status at regional, national, or continental levels.(c) To make a synthesis of the current knowledge on allochthonous flora of Italy.

Results and Discussion
The floristic data in the present work are the result of field and herbarium research carried out in twelve Italian regions: Basilicata, Calabria, Campania, Lazio, Liguria, Molise, Puglia, Sardegna, Sicilia, Toscana, Umbria, and Trentino Alto Adige.
In this study, 106 alien taxa are considered (Supplementary Materials Table S1).A summary of the data collected is shown in Table 1.Specifically, 89 first records, 27 changes in status, and 1 extinction are reported for the regions surveyed for a total of 117 new records.Table 2 shows the invasiveness status of the new alien taxa presented in this work.Most reports concern Calabria, with 39 casual alien, 6 naturalized alien, and 3 invasive alien taxa reported.An important number of taxa has also been contributed by the two main Italian island regions, where 12 casual alien, 1 naturalized alien and 4 invasive alien taxa are reported for Sardegna, and 12 casual alien and 3 naturalized alien taxa for Sicily.It is noteworthy that 11 status changes from naturalized alien to invasive alien are reported for some of the surveyed regions.Five of these taxa are also considered invasive aliens for the first time in Italy: Leucaena leucocephala (Lam.) de Wit subsp.glabrata (Rose) Zárate (Calabria), Bidens aurea (Aiton) Sherff (Sardegna), Jaborosa integrifolia Lam.(Sardegna), Melia azedarach L. (Calabria), Polanisia dodecandra (L.) DC. subsp.trachysperma (Torr.& A.Gray) Iltis (Toscana).There are also 23 new records of naturalized alien taxa, including 7 first regional records, while the other 16 are status changes; two of these taxa are considered for the first time as naturalized aliens in Italy: Lantana montevidensis (Spreng.)Briq.(Calabria) and Paspalum exaltatum J.Presl (Liguria).Also significant is the contingent of casual alien taxa recorded for the various regions surveyed in this study: 81 records attributable to 78 taxa.been erroneously first reported to Italy by Zanotti [48] instead of A. australis, as indicated in [27]) by bigger female bracts (more than 0.5 cm) and from the North American taxon Acalypha virginica L. by ovate-cordate female bracts with crenate-denticulate margin instead of deeply lobed [45,47,49].The spread of this species is probably promoted by nursery substrates, from which seeds or small seedlings can be dispersed [50].In most of the recorded localities plants growing both inside and outside pots hosting ornamentals have been observed.It is possible that this species could spread in the future especially in disturbed sites and green areas.
In Sicilia the species has been found in two Messina stands.First individuals have been observed in a garden on the island of Salina, where it has been traced the nursery origin of the seeds for over three years.Currently, the species behaves like a weed, producing hundreds of specimens.New individuals grow not far away along a roadside in a damp anthropized area.
Note.Acalypha virginica is a therophyte native to North America, reported as invasive, naturalized or casual alien in some Italian regions.This species is reported as an invasive alien in Liguria, Lombardia, Veneto and Friuli Venezia Giulia; as a naturalized alien in Piemonte, Trentino Alto Adige, Emilia Romagna, Toscana and Puglia; and as a casual alien in Campania and Calabria [43].
In Campania, this species has been reported only for Avellino, Napoli and Portici [51,52] without any geographical references.Here, we report three established populations observed over the years, located in cultivated areas and roadsides in the Colli Aminei area and Camaldoli hill in the city of Napoli.Based on our observations, we propose the status of "naturalized" in Campania for this species.
In Sardegna, several individuals of this species grow on disturbed soil, roadsides, and dumps, likely introduced through nursery and agricultural activities (e.g., contaminated growing substrates or infested phytocells).
Note.The species was found at the side of a mountain road with several individuals renewed since 2020 (V.L.A. Laface personal observation).In Italy, the species is reported in Emilia-Romagna as naturalized, while in Lombardia, Marche, Piemonte, Sardegna, and Veneto as a casual alien [43], and was recently reported for Toscana according to Galasso et al. [39].
Note.Actinidia deliciosa is cultivated worldwide for fruit yield [53].The observed individual grows on a slope climbing on chestnut trees; its origin is unknown, as there are no cultivated plants in the area.In Italy, it is reported to be a casual alien, especially in the northern and central regions bordering the Tyrrhenian Sea [43].
Note.In Italy, this species is reported especially in the Tyrrhenian regions [43].It is a new alien for Puglia.Only one specimen was found in a small pocket of soil on a vertical rock face near the town of Peschici, which probably escaped from pot cultivation.

7.
Agave Note.The specimen of Agave angustifolia subsp.angustifolia reported was observed and collected on a sandy beach where several private villas have a garden in front of the sea, outside of which they grow thorny plants to avoid bathers stopping.A coastal storm probably removed an adult individual and relocated him lying a few meters from the shoreline, in a higher position.Here, the plant continued to vegetate until it flowered and bore fruit, without giving rise to new shoots at the base.To date, this species is reported only for Sicilia and Puglia, representing the second record for the Italian peninsula [43].

8.
Agave Note.The observed individuals grow in the proximity of abusive dumps of inert and garden pruning waste material, probably deriving from waste cuttings from nearby gardens: in fact, A. attenuata subsp.attenuata is commonly used as an ornamental species.The areas where the observed individuals grow are not easily accessible, so they were probably not planted there, nor currently cultivated.In Italy, it is reported as a naturalized alien in Sardegna and casual alien in Lazio and Sicilia [43].
Note.Culton was domesticated from Allium vavilovii Popov & Vved., and is widely used as a food plant.Two individuals have been found along a road, probably coming from nearby cultivated plants.Allium cepa occurs throughout Italy as a casual alien and is unreported only in Valle d'Aosta, Trentino-Alto Adige, Liguria and Puglia [43].Note.Several spontaneously growing individuals were found in the Palabanda valley (Hortus Botanicus Karalitanus, Cagliari), likely introduced through weed seeds present in the topsoil.This species has previously been reported for several Italian regions as a naturalized alien in Emilia-Romagna, Marche, Toscana, Veneto, Umbria and as a casual alien in Friuli Venezia Giulia, Lazio, Lombardia, Trentino-Alto Adige and Sicilia [43].Note.Reported for several Italian regions as a casual alien or naturalized alien [43], A. emarginatus subsp.emarginatus is rare or more probably overlooked in Campania [51].These authors reported a specimen from the same population indicated here: its self-replacement by seeds for more than ten years allows us to regard this taxon as a naturalized alien in Campania.
Note.Abundant populations of Amorpha fruticosa were found on the Tiber river, colonizing gravel beds.This species is recorded as an invasive alien in most of north and central Italy, and it is naturalized alien in all of the Italian regions except Valle d'Aosta, where it is a casual alien [43].
Note.Annona cherimola is a food plant.Several individuals of different ages have been found in an irrigated Citrus groove nearby adult fruiting plants.The species is present in Italy as a casual alien only in Calabria [43].
Note.The new locality is the first for Ischia island, where A. cordifolia is to be regarded as a casual alien by now.Nevertheless, this finding confirms the invasiveness of the plant, apparently relying only on vegetative propagules in southern Italy [54].For the introduction and spontaneous diffusion of this species in Campania, as well as its diffusion throughout the mild zones of the region, see [51].Due to its rapidity of diffusion, the species fully meets the definition of invasive alien species proposed by Pyšek et al. [55].Furthermore, the local impact of A. cordifolia, especially on native vegetation, is impressive, especially when it covers trees with its rapid growth [56].For these reasons, we believe that the invasive status is more appropriate for this species, as already proposed for other Italian regions (Toscana, Sicilia) [43].

Araujia sericifera Brot.
Apocynaceae-Neophyte-South America-Climbing phanerophyte First record for Basilicata (casual alien) Change in status for Calabria: from casual alien to naturalized alien (naturalized alien) Specimina: 10 July 2023, old town of Scalea (Cosenza), roadside rainwater drainage, 39.818145 Note.Araujia sericifera is a liana native to central-east South America.The species has been reported in the flora of almost all Italian regions as a casual or naturalized alien [43] and in recent years it showed a rapid expansion moving from the status of casual alien to naturalized or invasive alien (e.g., Lazio, Campania) [57,58].In the regions reported here, the species was introduced about 10 years ago as ornamental.The Basilicata record fills the distribution gap of this taxon with the neighboring regions [57,59,60].
Note.Asparagus setaceus is commonly used as an ornamental plant.It spreads in wild environments having probably escaped cultivation in surrounding gardens.In the above localities, it was found in an abandoned orchard.It is present in southern Italian regions as a naturalized alien in Calabria [58], Campania and Sicilia, whereas it is a casual alien in Lazio, Puglia, Sardegna, Trentino-Alto Adige [43].17.Bauhinia purpurea L. [≡Phanera purpurea (L.) Benth.]Fabaceae-Neophyte-South Asia-Scapose phanerophyte First record for Italy (casual alien) and Europe Specimen: 9 August 2023, Via Salvatore Spinuzza, Palermo, interstices of the sidewalks and pots, 38.121363 • N-13.359845 • E, 30 m a.s.l., leg.E. Di Gristina, det.E. Di Gristina, G. Domina (SAF100132).
Note.Bauhinia purpurea is used for ornamental purposes due both for the attractive flowers and for its decorative foliage.Some individuals have been found in the interstices of the sidewalks and in the pots, probably coming from nearby adult fruiting plants.This is the first record for Italy and the European continent [61].The native range of the species is the Indian Subcontinent to Myanmar [61].Bauhinia purpurea is reported as introduced in South East Asia, West Australia, Queensland, Iraq, Central and South Africa, Central and South America.
Note.According to POWO, the native range of Bauhinia variegata is the Indian Subcontinent to China (S.Yunnan) [61].While conducting field surveys in Sicilia, several individuals were observed growing along the roadside of urban environments in Catania and Palermo.This represents the first record for Italy and Europe and it is considered as a casual alien species.It is likely that these plants escaped from private gardens.It is commonly grown as an ornamental tree in tropical and subtropical regions.This species has seeds that are dispersed by wind, allowing them to easily escape cultivation and establish in several habitats [62].Its seeds can remain viable for over a year, making it difficult to manage [63].Additionally, it has become an invasive alien species in the southern United States, South Africa, Canary Islands, and East Australia [64,65].
Note.This represents a complex of horticultural hybrids derived by South American species [43].The observed individual grows between the asphalt and the wall, born from seeds from nearby houses.In Italy, the species is reported as a casual alien only in Campania [66].

Bidens aurea (Aiton) Sherff
Asteraceae-Neophyte-North Central America-Scapose hemicryptophyte Extinct for Puglia Change in status for Sardegna and for Italy: from naturalized alien to invasive alien (invasive alien) Specimina: 27 October 2016, to the west of the town, at the beginning of the road to in Lamis, San Nicandro Garganico (Foggia), roadside, 41.823250 Note.Bidens aurea was recently indicated as a naturalized alien in Puglia, based on a report from a site in which it was collected 30 years before (San Nicandro Garganico, presso San Giuseppe) [25].In 2022, we could not find the species in the same site.Considering that the small occurring site has been transformed by paving works, B. aurea must be considered as an extinct alien species in Puglia.
In Sardegna, a population of numerous individuals was found within an area of approximately one hundred square meters (Sadali, Sud Sardegna).Moreover, we also observed several individuals along roadsides and in damp uncultivated fields (Sardara, Sud Sardegna).
Note.Bothriochloa laguroides, native to America, was reported as a naturalized alien in Liguria and Campania [43], but had never been found in the region before the present record.The collected specimens were growing in a dry mowed meadow characterized by many synanthropic and exotic species, such as Paspalum notatum Flüggé.
Note.Some individuals of Bougainvillea spectabilis were observed from pruning material from a nearby sports center (shooting range), where the plant grows for ornamental purposes on fence nets.In Italy, it is reported as a casual alien in Abruzzo and Sardegna [43].
Note.Broussonetia papyrifera is widespread in ruderal sites, spreading by vegetative reproduction.Besides Toscana, it was recently considered an invasive alien in the neighboring Lazio region [37].Broussonetia papyrifera occurs in all Italian regions except Valle d'Aosta.The species is an invasive alien in many regions of northern Italy and mainly a naturalized alien in the rest of the country [43].
Note.Some individuals of different ages and sizes of C. glauca, of which only one with flowers and fruit, emerged from the cracks of the road shoulder and the spaces between the prefabricated concrete components of the road ditch immediately before the bridge that connects Gasponi to Drapia.This species is reported only for Emilia Romagna and Sicilia as a casual alien [43]; therefore, this is the second report for the Italian Peninsula and the second for South Italy.
Note.Catalpa speciosa is an ornamental species native to North America.In Italy, it has been already recorded as naturalized in Piemonte and as a casual alien in Lombardia [43].In the surveyed site, the species forms a small population with mature trees already present at the time of the finding (2019) along the left bank of the Sieve River.Over 4 years of observation, the species has shown a gradual trend of expansion, and a few isolated specimens are already spreading in a nearby Quercus cerris L. woodland.
Note.Under a plantation established for reforestation purposes, abundant juveniles of C. atlantica up to 3 m tall have been found, suggesting that the species is naturalized in the area.The taxon is recorded in most Italian regions, but until now, it was considered naturalized alien only in Sardegna [43].
Note.One young individual of C. deodara, approximately 2m tall, was found along a pathway in a deciduous wood.Cedrus deodara was until now recorded as a casual alien in several regions of north and peninsular Italy and in Sardegna, while it is a naturalized alien in Lombardia [43].

Cenchrus longispinus (Hack.) Fernald
Poaceae-Neophyte-Central and North America-Scapose therophyte First record for Calabria (invasive alien) Specimina: 30 September 2023, Spiaggia di Praia a Mare, Praia a Mare (Cosenza), sandy beach dunes, 39.880544 Note.Cenchrus longispinus has been observed on the sandy dunes of the Praia a Mare, on the Thyrrenian side of the Cosenza province.It displays invasive behavior, occupying not only all the dunes for many kilometers, but also the flower beds and pavements nearby.The fruits have hooks that allow them to cling easily and firmly to animals and fabrics, but also to the skin itself, which allows them to be carried unintentionally for very long distances.It is reported throughout Italy as invasive alien except in Sardegna, Umbria, Trentino, Valle d'Aosta and Calabria [43].Note.Recently introduced as an ornamental grass, C. purpurascens escapes from flowerbeds and colonizes lawns and paving cracks.It spreads by means of hypogeal stolons and seeds.This species has been identified using the taxonomic key reported in [67].Until today, this species has been known only for a few central-north Italian regions [43]: therefore, this is the first record for Campania and South Italy.

Chamaecyparis lawsoniana (A.Murray) Parl.
Cupressaceae-Neophyte-California and Oregon-Scapose phanerophyte First record for Calabria (casual alien) Specimen: 14 August 2023, Gambarie, Santo Stefano in Aspromonte (Reggio Calabria), in a crack of a fence wall, 38.167825 Note.Chamaecyparis lawsoniana is a species native to some states of the United States [61], cultivated for ornamental and reforestation purposes in Italy, where it is reported as a casual alien in various regions of the central-north peninsula and in Sardegna [43].
Both specimens reported here grow in the cracks of various fence walls surrounding private villas where this plant is mainly grown for hedges.This is the first report for Calabria and South Italy.
Note.Culton domesticated from C. arietinum subsp.reticulatum (Ladiz.)Moreno & Cubero ex Del Guacchio & P.Caputo, widely used as a food plant.Some individuals have been found in uncultivated land, where the plant was presumably grown in previous years.Cicer arietinum subsp.reticulatum is present throughout Italy as a casual alien and not reported only for Valle d'Aosta, Liguria, Basilicata and Calabria [43].
Note.Some individuals of Citrullus amarus were discovered in abandoned fields in Siddi.In Sardegna, this species was likely extensively cultivated in the past for traditional food and medicinal purposes (e.g., sub Zidra [68]).Citrullus amarus is native to South Africa and is widely cultivated throughout the Mediterranean region, particularly in North African Mediterranean countries [69].Note.Citrus ×limon is a cultigen derived from artificial hybrids: the hybrid formula is C. maxima × C. medica × C. reticulata.It is a tree and grows primarily in the subtropical climatic belt.It is used to treat unspecified medicinal disorders, has environmental uses, as animal food and a medicine and for fuel and food [61].The individual observed is in a good state of conservation, without particular pathologies, it is tall about 3 m and in the future, it could suffer the probable closure of the sclerophyllous vegetation.In Italy, Citrus ×limon occurs only in Sardegna and Campania as a casual alien [43].Note.Although C. trichotomum is widely used and studied for its numerous medicinal properties [70][71][72], in Italy, it has been introduced and is used for ornamental purposes.Already reported as a casual alien in several Italian regions [43], the collected specimen was found together with other well-developed and vigorous plants, probably originating from an older individual along the SP3 Provincial Road.Note.Coleus scutellarioides is a culton originated from plants introduced from South East Asia, where it is widely and traditionally used for medicinal purposes and for ornamental purposes due to its highly decorative variegated and multicolored leaves [61].The species was first introduced into Europe from Java in 1851 by a Dutch horticulturist.The diffusion as an ornamental plant increased considerably in the 1980s following the selection of cultivars with very colored and variously shaped leaves.It was reported as a casual alien both in Lombardia [73] and more recently in Calabria [58].Some plants, probably spread by seeds from urban green flowerbeds, were observed in the old town of Maratea (Basilicata).

Lamiaceae-Neophyte-South East Asia-Scapose phanerophyte
In Sicilia, one individual was found at the base of a wall, probably coming from nearby adult fruiting plants.Note.Cucumis melo is considered one of the most important horticultural crops in the world.It is probably native to Asia [74] or Africa [75].Cucumis melo shows a good resistance to variable soil saline concentrations and it is often grown along the Mediterranean coasts due to the warm climate [76].A small group of flowering plants has been observed on a sandy beach a few meters from the sea, along with halophilous native species such as Cakile maritima Scop.subsp.maritima, Crithmum maritimum L., Salsola sp. and the alien Solanum lycopersicum L. In the first stand, seeds could have been probably dispersed through food wastes.In the second stand, a single plant emerged from a rainwater drainage grate, probably as a result of seed dispersal from the balconies of various apartments occurring along the street.

C.M. Musarella (REGGIO).
Note.Cycas revoluta is an ornamental tree cultivated both in pots or in the field.Only one individual was found with just a leaf sprouted under a water tank abandoned in a water drainage channel.The emerging leaf was collected with some difficulty, but easily allowed taxon recognition.The young individual probably formed from an adventitious shoot thrown from one of the many apartments that line the motorway junction and on whose balconies and terraces various adult plants in pots are grown.Cycas revoluta was recently recorded for the first time for Italy as a casual alien [77]: this is the second record for the Italian Peninsula and the first for South Italy and for Calabria.Note.Dozens of individuals of C. proliferus subsp.proliferus, varying in age, have been found in uncultivated areas and trail margins, often in association with Medicago arborea L. It is hypothesized that they were historically introduced as fodder plants.Notably, experimental grasslands were established at the discovery site since the early decades of the 19th century [78].While experimental cultivation of C. proliferus subsp.proliferus for forage purposes was documented in Lipari [79], there was no evidence of successful reproduction and naturalization.The taxon, originally from the Canary Islands [80], was not documented in previous scientific works across continental Europe and Mediterranean islands [55].On the contrary, Cytisus proliferus is introduced into Australia, California, East Tropical Africa, Hawaii, India, Jawa, and New Zealand [61], and it is considered an invasive alien plant in California, Australia, and New Zealand [81].
Note.Dahlia imperialis is a native American species cultivated in much of the world for ornamental purposes [61].The individual appears as a small tree with many suckers; numerous seedlings have been observed in the nearby area.Dahlia imperialis is present in Italy as a casual alien, exclusively in Liguria [43].
Note.According to the [43], D. racemosa occurs as a casual alien species in Emilia-Romagna, Friuli Venezia Giulia, Lazio, Liguria, Lombardia, Trentino-Alto Adige, Toscana, and Veneto.During fieldwork in Sicilia, it was observed in the territory of Sant'Agata li Battiati (Catania) along the roadside.This is the first record of the species being classified as a causal alien species for Sicilia.
Note.Diospyros lotus was until now known as naturalized alien throughout north and central Italy [43], while it is missing in the more southern regions and islands, probably also due to the less favorable climatic conditions.The discovery in Sicilia concerns a single specimen on the edge of a dense forest dominated by Quercus congesta C. Presl  Note.Diospyros virginiana has previously been reported only once for Italy by [27] who reported it for Elba island (Toscana), where the species is naturalized.Diospyros virginiana in Sicilia has been observed in various locations on Etna and on the south-west outskirts of Catania where it sometimes forms small but dense populations in habitats such as abandoned crop areas, edges of cultivated fields, roadsides, demonstrating a good propagation capacity from root shoots and perhaps from seeds.The species bears fruit regularly and was probably introduced as a rootstock for Diospyros kaki Thunb.Regarding the Diospyros genus in Sicilia, Spadaro and Raimondo [82] reported a case of spontaneization of D. kaki in the province of Agrigento.Note.Drosanthemum floribundum is an ornamental species native to the Cape Province, expanding itself in many countries due to its use in gardening, vigorous flowering, groundcover character and replacement of Carpobrotus sp.[83].It easily reproduces vegetatively, producing long stolons [84,85], hence the vernacular name 'Jupiter's beard' [86], which produce adventitious roots at each internode, easily generating new individuals.The individual observed probably came from some plants grown as ornamentals hanging from the balconies above.Note.A population of Dysphania pumilio covering a surface exceeding 100 square meters has been found on a patch of grassland, mainly composed by Ampelodesmos mauritanicus (Poir.)T.Durand & Schinz and scattered specimens of Euphorbia rigida M.Bieb.Dysphania pumilio, native to Australia, is known as a noxious weed in several countries all over the world [87][88][89][90][91].In Italy, it was found for the first time in Milan (Lombardia) in 1939 [92].Note.Euphorbia serpens has been reported as an introduced weed in disturbed sites in many European countries [95][96][97].Seeds could have been transported accidentally, maybe with nursery substrates [98].All the surveyed sites have been observed scattered populations, each composed of a few individuals showing good adaptation to the highly stressful conditions of the urban environment.The collected material has been ascribed to the nominal subspecies (reported for many Italian regions as naturalized alien according to [43]), differently from subsp.fissistipula (Thell.)Verloove & Lambinon, on the basis of connate stipules.Note.The Calabrian stand of E. japonica, a taxon already known in other Italian regions as a casual alien or naturalized alien [43], could spread in the surroundings due to the availability of similar habitats and affecting native herbaceous riparian and forest communities.Note.Asiatic species commonly cultivated as an ornamental, the observed individual of F. japonica is probably generated from pruning waste from nearby villas.In Italy, F. japonica is reported for Liguria, Sardegna and Toscana as a casual alien [43].Note.Fragaria ananassa is a fixed hybrid between F. chiloensis (L.) Mill.× F. virginiana Mill.and it is widely cultivated as a food plant.Some mature individuals have been found in the interstices of the sidewalks, probably coming from nearby adult fruiting plants.
Note.Gaillardia ×grandiflora has beautiful flowers and for this reason, it is commonly used as an ornamental plant [99] and it is well adapted to Mediterranean climate habitats [100].The individuals observed are derived from seeds of cultivated plants.In Italy, it is reported in Abruzzo, Emilia-Romagna and Lombardia as a casual alien [43].Note.Hundreds of individuals of Gazania ×splendens are thriving in grasslands and Mediterranean shrublands along a stretch of coastal countryside within the municipality of Porto San Paolo (north-east Sardegna).These plants may have originated from cultivation at a nearby tourist residence and are rapidly spreading within the natural environments of the surrounding areas.A similar situation has been observed along the south-west coast of Sardegna, specifically in the locality of Su Portu'e Su Trigu (Sant'Anna Arresi, Sud Sardegna province), where the taxon has proliferated in grasslands, scrublands, and sandy and rocky areas near the coast.In this case, as well, it has escaped from neighboring villas.
Note.According to some scholars (i.e.,: [101]), G. pellucida is a hygrophilous species; indeed, the individuals collected grow along a drainage channel of a fountain where the water flows and at the level of the internodes they formed adventitious roots [101].According to Portal to the Flora of Italy [43], in Italy, this species is reported as a casual alien exclusively in Veneto and hase been mistakenly recorded in Trentino-Alto Adige.Note.Glycine max (soybean) is a species largely cultivated mainly in central northern Italy.This species is reported as a casual alien in Piemonte, Lombardia, Veneto, Emilia Romagna, Marche and Umbria [43].Therefore, our recent findings in the Ansanto Valley, in Avellino province, are the first in Campania and concern a few plants spread by seed, probably escaped from cultivation.In Italy, it is reported as a casual alien in Campania, Lazio and Sicilia [43].

Impatiens balsamina L.
Balsaminaceae-Neophyte-India and Sri Lanka-Scapose therophyte First record for Calabria (casual) Specimina: 11 October 2021, Ortì Inferiore, Reggio Calabria, water drainage channel at the roadside, 38.145783 Note.Impatiens balsamina is native to South Asia and it is an annual plant commonly known as "garden balsam" or "rose balsam".It is used in Indian traditional medicine for various diseases and human physiological conditions [102].In Italy, it is cultivated as an ornamental plant, for its autumn flowering.The plants found in drainage channels originated from seeds coming from nearby villas.

Isatis tinctoria L. subsp. tinctoria
Brassicaceae-Archaeophyte-East Europe and Turkey-Biennial hemicryptophyte Change in status for Puglia: from invasive alien to naturalized alien (naturalized alien) Specimina: Note.Lampranthus roseus is cultivated for ornamental purposes [109].The collected individual was growing in a crack between the wall and the road where it probably originated from seeds coming from plants grown on nearby balconies.In Italy, the species is reported as a casual alien in Campania, Puglia, Sardegna and Toscana [43].

Lantana montevidensis (Spreng.) Briq.
Verbenaceae-Neophyte-South America-Nanophanerophyte First record for Basilicata (casual alien) Change in status for Calabria and for Italy: from casual alien to naturalized alien (naturalized alien) Specimina: 12 April 2022, SS 18 near a road junction, Tortora, Cosenza, abandoned rest area at the road junction, 39.922464 Note.Lantana montevidensis is considered highly invasive in the southern United States, Hawaii and Australia [110] because it is rapidly replacing the pasture's native plants on shallow, dry, stony soils.This species resists prolonged periods of heat and drought and in recent years, it has been observed propagating along the southern Tyrrhenian coast together with L. camara on roadsides and in urban green areas of the coast.It was reported as a casual alien in Calabria [52], Sardegna [111] and Liguria regions [112]  Note.The native range of Leucaena leucocephala subsp.glabrata is from Mexico to Honduras [61], reported for Italy only in some regions as a casual or naturalized alien [43].This plant was first reported as a casual alien for the Calabria region (only in the Metropolitan City of Reggio Calabria) and continental Italy by Musarella et al. [59].It was later reported as a naturalized alien for the region by Stinca et al. [58], because many adults at different growth stages, with different inflorescences and mature fruits, were found in new and old localities also in other Calabrian provinces and all producing many seedlings.This taxon continues to spread rapidly along city roadsides, highways and railways, as well as in the cracks of the sidewalks, germinating easily from the many scattered seeds.The finding of new adult individuals, apparently having an age of more than 10 years, and juveniles widespread near and far from them at already known sites and in new localities in the provinces of Reggio Calabria and Catanzaro justifies properly considering L. leucocephala subsp.glabrata as an invasive alien for the region and, then, for Italy.Note.Species introduced in Europe as an ornamental plant with several varieties, Lobelia erinus easily spreads in urban environments where it is found as a casual alien species [43].The specimen observed in Pellaro has grown in a crack in a wall during its flowering period.Both observata individuals above reported probably come from the neighboring house, where this species is commonly cultivated.
Note.A flowering individual of L. barbarum was found in the center of the fiumara not far from a horticultural area where a well-developed plant with flowers and fruit was observed.

Melia azedarach L.
Meliaceae-Neophyte-South Asia, Malaysia, Indonesia and Australia-Scapose phanerophyte Change in status for Calabria and for Italy: from naturalized alien to invasive alien (invasive alien) Specimina: 28 July 2021, Copanello di Stalettì by the mouth of Alessi river (Catanzaro), amongst windbreak hedges along the road, 38.7692208 • N-16.5673852 • E, 3 m a.s.l., leg. A. Capuano, det. A. Capuano, G. Caruso (REGGIO); 8 August 2022, Gagliano old town along Via Filippo Smaldone, Catanzaro, roadside and sidewalk crubs along with Lantana camara s.l., 38.920968 Note.Melia azedarach, introduced as an ornamental species, is commonly cultivated as a street tree throughout the region.It was first reported in Calabria (Cosenza Province) as a casual alien species in 2015 [113] and subsequently considered a naturalized alien in 2021 [58].In recent years, it has been noticed that spontaneous seedlings observed in previous years have quickly and successfully colonized numerous suburban and urban areas, spreading mainly in disturbed roadside habitats and urban open spaces, but have also been observed along some fiumarerivers that have been heavily disturbed by human activities and roadsides.This species is very well adapted to the Mediterranean climate [114]; in fact, in South Africa, it is considered a highly invasive alien species with extremely rapid growth, listed as one of the top ten invasive alien plants in terms of the area in which it grows [115].Melia azedarach is considered, moreover, one of the most important exotic plants transforming natural habitats [116].The finding of new adult individuals, apparently having an age of more than 10 years, and juveniles widespread near and far from them at already known sites and in new localities in the metropolitan city of Reggio Calabria, justifies properly considering M. azedarach as an invasive alien for the region and, then, for Italy.Note.Many individuals of Moeroris tenella were discovered as weeds in various ornamental plant pots within the Hortus Botanicus Karalitanus (University of Cagliari).Subsequently, scattered plants were observed in neighboring sites of the Palabanda Valley (Cagliari) in open fields, particularly in damp and shaded environments.Moeroris tenella was previously documented in only three other regions of Italy: Liguria and Calabria as casual occurrences, and in Sicilia as naturalized alien, as reported by the Portal to the Flora of Italy [43].
Note.Momordica charantia is an Asian plant cultivated for food purposes and rarely escaped cultivation in Emilia Romagna and Lazio, as previously observed by Alessandrini and Montanari [117] and Lucchese [118].A few individuals that escaped cultivation were found along roadsides and hedges in the colluvial area of Tanca Manna, in Capoterra (Cagliari).Note.Myoporum laetum is used for ornamental purposes.One individual was found at the base of a wall, probably coming from nearby adult fruiting plants.The species is present in Italy as a naturalized alien in Sardegna, while in the past, it was reported by mistake for Puglia and Toscana [43].Note.Nassella neesiana was observed abundant also in Chiappino (Cogoleto).The species is known to be alien in the USA (Alabama), Europe (Great Britain, Germany, Italy, Iberian and Balkan Peninsula), South Africa, east Australia, Tasmania, New Zealand [61].In Italy, it is currently a naturalized alien in Lazio and Toscana and a casual alien in Calabria, Emilia-Romagna, Liguria and Veneto (Portal to the Flora of Italy, 2023).Now, it must be considered definitely a naturalized alien in Liguria as well, where it has greatly spread compared to the previous indication by Verloove et al. [119].Note.In Puglia, it is an alien taxon because it does not grow in its typical environment as in other regions of south Italy, such as Calabria, where, with some species of the genus Tamarix, it forms a protected habitat along the river.In Puglia this taxon has escaped cultivation as an ornamental cultivar: in fact, it is observed in different environments from its ecology.The observation above refers to the "Pink Beauty" cultivar, which is one of the most widespread varieties on the market and widely used in Puglia, not only in public gardens but also along the highways.It has a simple pink flower with a diameter of about 6 cm.It was observed in two coastal places in the municipalities of Monopoli (Bari) in two different vegetations: within the shrub plant community with high coverage of Pistacia lentiscus at Torre d'Orta, and near Torre Incina in uncultivated vegetation with sub-nitrophilous species.Note.Ocimum basilicum is universally cultivated as an annual herbaceous plant originating from the Asian continent and it is used as a culinary herb [120].The species has been reported in the alien flora of many Italian regions as a casual alien [43].It is a synanthropic species occasionally found in various types of environments such as rural and ruderal [118,121,122] and riverbeds [32,123].The individuals observed grew in a ruderal environment and originated from plants grown nearby.
Note.Several individuals of O. gaura were found in the locality of Margine Rosso in Quartu S. Elena town, along a roadside and on sandy places, and probably escaped from the gardens.Note.In Italy, O. stucchii is reported as a naturalized or invasive alien for many regions, but not in Puglia [43].Very dense populations are found in the sandy shoreline of Isola Varano, and in the backdune near a crop in the Capojale area.Inside the stands, the species is fastly spreading.
Note.Currently, P. exaltatum is present extra patriam only in Italy (Liguria), where in recent decades it has demonstrated an ability to robustly expand on the edges of the road in question starting from the report by Verloove & Reynders [124] and presumably elsewhere in the same territory.Note.The individuals of P. frutescens observed in the cracks of a wall and in drainage channels probably come from plants grown on the nearby balconies and gardens.Perilla frutescens is widely cultivated, especially in its native area for medical, culinary, and ornamental purposes [125,126].Based on the morphology and color of the leaves, the material collected can be referred to as the var.crispa (Bentham) Deane ex Bailey [125].Note.Persicaria capitata was reported in many peninsular regions, in Sicilia and in Sardegna [43].In particular, this species was known as a naturalized alien in Campania [127] and as a casual alien in Puglia [128] and in Calabria [52].Therefore, with this new finding, the last three regions stand in territorial continuity with Basilicata, where P. capitata occurs in urban and ruderal environments on rocky or debris substrates, as in neighboring regions.

Persicaria senegalensis (Meisn.) Soják
Polygonaceae-Neophyte-Africa, Madagascar and Arabian Peninsula-Scapose therophyte First record for Continental Europe (naturalized alien) Specimina: 5 September 2023, Saline Joniche, Montebello Jonico (Reggio Calabria), drainage for water at the roadside, 37.940408 Note.The numerous individuals of P. senegalensis observed grow inside a water drainage channel, where the flow is constant: the population also occupies a big part of the beach below.The species was reported for the first time in Europe in Crete Island [129] and in Italy only in the Pantelleria Island [130]: therefore, this is the first report for continental Europe.Persicaria senegalensis is a species that attracts particular attention because it has a very high reproductive capacity, both gamic and agamic, which allows it to rapidly colonize very large areas near water.

Petroselinum crispum (Mill.) Fuss
Apiaceae-Archaeophyte-Algeria, Greece, Morocco and Yugoslavia-Biennial hemicryptophyte Change in status for Puglia: from casual alien to naturalized alien (naturalized alien) Specimen: Note.Phoenix canariensis was reported as a naturalized alien for the Calabria region by Galasso et al. (2018a), but recently, it changed status from naturalized alien to casual alien [59].In the Diamante site, the species is present with seven young specimens of different ages, coming from zoochorous dissemination of the seeds of the palm trees grown in the nearby gardens.In addition, new observations were made in different parts of the Calabria region.For this reason, we now consider that P. canariensis could be considered a naturalized alien.
Phoenix canariensis, native to the Canary Islands, has become a popular ornamental plant in Europe, in the Mediterranean area and also in Australia, California and Florida, where it is largely cultivated as a garden or landscape species in public and private spaces [131,132].It is a dioecious plant that can produce up to 30.000 dates per year, resulting in a great source of fresh food for the wild avifauna especially in urban environments, both in its native area and outside of its natural range [133,134].Its abundant fruiting, often conveyed by zoochory, led this palm to spread extensively outside of cultivation, bringing it to develop in a wide range of habitats, from man-made to natural environments often far away from the mother plants.Phoenix canariensis was reported as a naturalized alien for the Calabria region by Galasso et al. [27], but recently it changed status from a naturalized alien to a casual alien [59].In recent years, new observations have been made in different parts of the Calabria region, especially in the Catanzaro province.For this reason, we now consider that P. canariensis could be treated as a naturalized alien.In the surveyed stands, P. canariensis showed great adaptability in terms of habitats and substrates: we observed populations developing on different soil typologies, from sandy or rocky spots on the coastline to clayey slopes or alluvial sites in the immediate inland.Although several stands host young and non-fruiting plants (at least for the moment), we also found mature specimens actively fruiting and disseminating in the surroundings.Also, some new seedlings were developing very far away from the putatively naturalized alien mother plants.It can be stated that P. canariensis is well established in Calabria and further investigations across different areas of the region will reveal new stands.Moreover, the increasing global temperatures will help subtropical floristic elements to find better conditions for their development.Although in recent years, several cultivated plants have been decimated by the Asian palm weevil Rhynchophorus ferrugineus (Dryophthoridae), it is expected that the spread of new seedlings and the stabilization of new populations could affect many more native communities in the future, especially in natural environments as already reported for other Italian regions [135,136].Note.Phyllostachys aurea is recorded as a casual or naturalized alien in many Italian regions, while it shows a distribution gap only in Trentino Alto Adige, Marche, Basilicata and Sardegna [43].In Basilicata, the collected specimen of this species, cultivated for ornamental purposes, probably comes from a small population, which acts as a hedge in a nearby villa.A small population was also observed in an uncultivated area between the motorway and an industrial area in Trentino Alto Adige and this finding is the first for the region.
Note.Physalis peruviana is an herbaceous perennial species that has been very widely introduced across the world from South America as a cultivated plant for its fruit, as a medicinal plant, and as an ornament.It is reported as a casual alien in several regions and as naturalized in Sicilia [43].In south Italy, it is recorded as a casual alien previously from the Puglia, Sicilia and Calabria regions [27,111,137].It is classified as an invasive alien plant at the global level [138].The species grows wild on sandy soils in fallow fields [28,111], river banks and lake shores [28].The plants regularly develop flowers and fruits.
Note.In the past, Pinus elliottii has been used for reforestation and public greening in some places on Sardegna island.Renewal phenomena are sporadically observed with plants of all age classes.In the mentioned site, several plants have been observed on roadsides, originating from some nearby roadside tree plantations.According to Euro+Med plantbase [80], the species is not recorded in Europe even as a casual alien, while it is considered a naturalized alien in some parts of Argentina, Australia, Hawaii, New Caledonia, South Africa, and Zimbabwe [139][140][141][142].
Note.Polanisia dodecandra subsp.trachysperma abundantly colonizes a stretch of the Tiber river, where it invades the EU habitat 3250, threatening the endemic Santolina etrusca (Lacaita) Marchi & D'Amato as previously highlighted in nearby areas [143,144].This taxon is reported for only a few Italian regions: it is considered a naturalized alien in Toscana, Lombardia, Piemonte and Emilia Romagna, and a casual alien in Lazio and Liguria [43].Very abundant populations (thousands of individuals) were found on the bed of the Possera stream, near the confluence with the Cecina river.Its presence in the area was already known, as reported by Selvi and Bettini [145].The species is also present on the Trasubbie stream as reported by Frignani et al. [146] and on the Merse river as reported by Landi et al. [147].
Note.Several individuals of Portulacaria afra were found in a water drainage channel, among other several alien species.They were probably formed from leaves and broken twigs of plants grown on the balconies and terraces of the many apartments that line the motorway junction.08.630824 • E, 169 m a.s.l., SE, leg.G. Galasso, det.G. Galasso, E. Banfi (MSNM barcodes MSNM52537, MSNM52538, MSNM52539, MSNM52540).Note.The same population observed in 2005 and 2007 [119] has been maintained by expanding along the slope.
Note.Robinia pseudoacacia is a North American tree that has become a naturalized or invasive alien species in most European countries [80].In Sardegna, in recent years, the species has become invasive alien in deciduous forests, particularly in the Sarcidano and Barbagia subsectors.The most affected habitats include riparian woodlands dominated by alder [Alnus glutinosa (L.) Gaertn.] and oak forests primarily composed of Quercus dalechampii Ten. and Q. ichnusae Mossa, Bacch.& Brullo (both species now included under Quercus pubescens Willd.subsp.pubescens).In other parts of Sardegna, R. pseudoacacia is mainly confined to roadsides and railroads.
Note.Ruellia simplex has been reported to Italy only for Sardegna, Puglia, Lazio [23,94,149] and recently for Sicilia [38].A small population has been observed along the roadside, in a ruderal site where other alien species (such as Cenchrus setaceus (Forssk.)Morrone, Amaranthus viridis L. and Salvia ×floriferior Dolat.& Ziel.) occur.Seeds or plant fragments could have dispersed from individuals cultivated in neighboring areas.Ruellia simplex is considered an invasive alien species in the South-East U.S.A., Australia and Pacific archipelagos [150].Note.The genus Perovskia (Kar.)J.B.Walker, B.T.Drew & J.G.González, later reduced at the subgeneric rank and included into Salvia [151], counts about eight species distributed over arid regions of Asia [125], whose identification and nomenclature are complicated by several hybrids and cultivars selected by gardeners.Considering the morphological features of leaves, different from the supposed parental species, the collected material has been ascribed to the hybrid S. abrotanoides × S. yangii according to Galasso et al. [25] and Dolatowski et Zieli ński [152].The nomenclatural combination we report here is in accordance with IPNI [153].Plants found in this first Calabrian site probably originated from material cultivated in the surroundings.
Note.A partially rotting adult individual and a couple of young individuals of S. spachiana were found near a large pile of waste and disused objects inside a former grassland now overgrown with tall grass, outside the perimeter wall of a camping.The species was found in a disused area, completely incorporated into an urban area and colonized by synanthropic vegetation.In addition to the oldest individual most likely deriving from an old house plant disused and thrown away in the area, other individuals of different ages and sizes are observed below, given the arrangement probably deriving from root shoots of the older specimen.
Note.A couple of individuals of S. pseudocapsicum of different ages and sizes, of which only one with flowers and fruits still present, were found inside a fiumara, on the edge of an illegal landfill bordered on three sides by reeds in Arundo donax L. and on one side by flooded section of the fiumara.Note.Sorghum bicolor is the fifth-most-produced cereal in the world and it is a source of nutrients and bioactive compounds for the human diet [154].It is also used as an efficient biomass accumulator and has potential use as a cellulosic biofuel [155].In Italy, it is now reported in all regions except Molise, Liguria and Valle d'Aosta [43].
Note.Sorghum halepense is widespread in fields, shores and ruderal sites in the area, so it should be considered an invasive alien for Umbria like in most Italian regions [43,156].Note.Spinacia oleracea subsp.oleracea is a culton domesticated from Spinacia oleracea subsp.turkestanica (Iljin) Del Guacchio & P. Caputo, widely used as a food plant.Some individuals have been found along a farm road, along the fields where the plant is cultivated.Spinacia oleracea subsp.oleracea is present in Italy as a casual alien in Lombardia, Veneto, Emilia-Romagna, Toscana, Marche, Umbria, Lazio, Abruzzo and Sardegna [43].
Note.According to the Portal to the Flora of Italy [43], S. secundatum can be found as a casual alien species in Basilicata, Calabria, Campania, Liguria, Puglia, Sardegna and Sicilia.Moreover, it has only been observed as a naturalized alien in Toscana at present.Our recent research in Sicilia has revealed that this species is gradually spreading and becoming a naturalized alien in various areas of the island.Hence, it is crucial to update the status of this species to naturalized alien.Note.Styphnolobium japonicum was already reported as a casual alien species in several Italian regions [43].The collected specimen was found with two other juveniles probably coming from an adult tree located not far away, found together with other alien species.Other juveniles and seedlings were observed in some streets of downtown Reggio Calabria, close to planted adult individuals.
Note.A few individuals of T. stans were found along the artificial riverbanks of Rio Concias (S.Sperate, Sud Sardegna), and probably escaped from confining gardens.In Italy, this species is only documented in Calabria, where it was first reported in Europe [157].Note.Tradescantia pallida was reported recently as a casual alien of synanthropic and urbanized environments in the neighboring regions of central-southern Italy [34,52,66].The species is widespread as an ornamental plant and it could potentially become a naturalized alien due to its lively vegetative reproduction.Note.Triticum aestivum subsp.spelta is occasionally cultivated in Sardegna.Several individuals were found as weeds in the cultivated fields of durum and bread wheat.This taxon is only reported for Campania as a casual alien [51].Note.Triticum turgidum subsp.dicoccon is increasingly cultivated in Sardegna and is commonly found as a weed in durum wheat cultivation.This taxon is documented as a casual alien in three other regions of Italy: Campania [93], Lombardia [50] and Toscana [158].
Note.A few individuals of U. pumila were found at the bottom of a wall.This species is currently spreading in central Italy, where it is widely naturalized [35,58].This species is naturalized as well in many regions of northern Italy and in Puglia, while it is considered an invasive alien in Piemonte and Valle d'Aosta [43] and a casual alien in Calabria [7].Note.Culton domesticated from Vicia lens subsp.orientalis (Boiss.)Galasso, Banfi, Bartolucci & J.-M.Tison, V. lens subsp.lens is widely used as a food plant.Some individuals have been found in uncultivated land, where the plant was presumably grown in previous years.This taxon is present throughout Italy as a casual alien and is not reported only in Valle d'Aosta, Veneto, Molise, Basilicata and Calabria [43].
Note.Vitis riparia grows within riparian vegetation along the Tiber river.It is present in 10 Italian regions and it is considered invasive alien in Piemonte, Lombardia, Toscana, Marche and Abruzzo [43].

Yucca gigantea Lem.
Asparagaceae-Neophyte-Central America and Mexico-Caespitose phanerophyte First record for Sardegna (casual alien) Specimen: 13 April 2022, Stani Saliu, Sestu (Cagliari), agricultural and rural habitats, 39.330941 Note.Zinnia elegans is native to Central America [61].It is commonly used as an ornamental plant; the seedlings observed along the roadside probably came from nearby gardens and villas.Zinnia elegans is present in several Italian regions as a casual alien [43].

Italian Alien Flora Update
The current amount of the Italian alien flora [43] of 1659 specific and subspecific taxa (excluding taxa reported by mistake, doubtful species, data deficient, historical records, and extinct) is updated to 1666 thanks to the new records presented in this study.Of the seven new records for Italian alien flora, two are new for Europe (Bauhinia variegata L., Pinus elliottii Engelm.), one for continental Europe (Persicaria senegalensis (Meisn.)Soják), three for Italy (Bauhinia purpurea L., Citrullus amarus Schrad., Cytisus proliferus L.f. subsp.proliferus) and one for the Italian Peninsula (Portulacaria afra Jacq.).
The current amount of the Italian flora (native + alien, excluding the taxa reported by mistake, doubtful species, data deficient, historical records and extinct) including the new records reported in this study is 9303 taxa.
Comparing the contributions of various Italian authors [27,43,58,[159][160][161] over the past 14 years with the data provided by this study, there is a steady increase in allochthonous taxa (Table 3, Figure 1).The current amount of the Italian flora (native + alien, excluding the taxa reported by mistake, doubtful species, data deficient, historical records and extinct) including the new records reported in this study is 9303 taxa.
Comparing the contributions of various Italian authors [27,43,58,[159][160][161] over the past 14 years with the data provided by this study, there is a steady increase in allochthonous taxa (Table 3, Figure 1).A steady increase in alien taxa is observed in all Italian regions, some of which, such as Trentino Alto Adige and Sardegna, are over 200%.The average percentage increase for Italian regions is more than 100% (Table 4).Table 3. Consistency of alien flora from 2010 to present for the 12 Italian regions surveyed with this study.In detail, the works consulted and the reference year of the data considered: Celesti Grapow et al. [159]: 2010; Galasso et al. [27]: 2018; Bartolucci et al. [160]: 2020; Bartolucci et al. [161]: 2021; Stinca et al. [58]; Portal to the Flora of Italy [43]: 2023; data updated with the present study: 2024.The percentage of alien flora in the various regions (Degree of floristic pollution) varies between 7.6% in Valle d'Aosta, to 23.5% in Lombardia and Trentino Alto Adige, with an average value for the Italian territory of 19.9% (Table 4).This value is not really significant for the area surveyed unless the surface is taken into account, thus assessing the density of alien taxa, which is highest in regions of north Italy such as Liguria (0.73), Trentino Alto Adige (0.72), Friuli Venezia Giulia (0.71), Veneto and Lombardia (0.68), while it is minimal for southern regions such as Basilicata (0.60) and Puglia (0.61) (Figure 2).The analysis of the life forms of the 106 alien taxa added to the Italian flora in this contribution shows that phanerophytes correspond to 38%, followed by therophytes with 25%, and hemicryptophytes with 18%, with the other life forms having smaller percentages (Figure 3).The predominance of phanerophytes is most probably due to the fact that these are mostly species introduced for ornamental purposes as Bauhinia variegata L., Pinus elliottii Engelm., Bauhinia purpurea L., Styphnolobium japonicum (L.The analysis of the life forms of the 106 alien taxa added to the Italian flora in this contribution shows that phanerophytes correspond to 38%, followed by therophytes with 25%, and hemicryptophytes with 18%, with the other life forms having smaller percentages (Figure 3).The predominance of phanerophytes is most probably due to the fact that these are mostly species introduced for ornamental purposes as Bauhinia variegata L., Pinus elliottii Engelm., Bauhinia purpurea L., Styphnolobium japonicum (L.) Schott, Chamaecyparis lawsoniana

Materials and Methods
Newly introduced alien plants in the Italian and European territories and changes in the invasiveness status of species already present in the territory were considered here, in accordance with Pyšek et al. [55].The specimens collected and examined are deposited in the following public herbaria registered in the Index Herbariorum (according to Thiers The floristic list of the taxa is reported in alphabetical order and follows the updated nomenclature and regional distribution of the checklist of the Italian vascular flora available on the Portal to the Flora of Italy [43], referable to the checklist of the flora alien to Italy [27] and subsequent updates [28][29][30][31][32][33][34][35][36][37][38][39].
The following information is provided for each taxon: updated scientific name, basionym (if present) and most relevant synonyms obtained from consultation of the sites Portal to the Flora of Italy [43] and IPNI [153]; family and biological form according to Flora d'Italia [167] [also available at IPFI: Index Plantarum of Acta Plantarum [183]; the range of origin according to POWO [61] and EPPO [184], period of introduction in Italy (i.e., archaeophyte or neophyte) according to "Portal to the Flora of Italy" [43], the invasiveness status (according to [55]) and whether the species is reported for the first time at regional, Italian or European level or whether a change in status has occurred.
For each taxon reported, the place of discovery and if the sample is a specimen or more specimina (with deposited herbarium specimen or specimina), observatum or more observata (species observed growing in the wild) are also indicated.The following specific information on the collection or observation site(s) is also included: toponym (according to the "Geoportale Nazionale" [185], locality, municipality, province or metropolitan city (either of the latter two are indicated in parentheses only when they do not correspond to the

Materials and Methods
Newly introduced alien plants in the Italian and European territories and changes in the invasiveness status of species already present in the territory were considered here, in accordance with Pyšek et al. [55].The specimens collected and examined are deposited in the following public herbaria registered in the Index Herbariorum (according to Thiers [162] The floristic list of the taxa is reported in alphabetical order and follows the updated nomenclature and regional distribution of the checklist of the Italian vascular flora available on the Portal to the Flora of Italy [43], referable to the checklist of the flora alien to Italy [27] and subsequent updates [28][29][30][31][32][33][34][35][36][37][38][39].
The following information is provided for each taxon: updated scientific name, basionym (if present) and most relevant synonyms obtained from consultation of the sites Portal to the Flora of Italy [43] and IPNI [153]; family and biological form according to Flora d'Italia [167] [also available at IPFI: Index Plantarum of Acta Plantarum [183]; the range of origin according to POWO [61] and EPPO [184], period of introduction in Italy (i.e., archaeophyte or neophyte) according to "Portal to the Flora of Italy" [43], the invasiveness status (according to [55]) and whether the species is reported for the first time at regional, Italian or European level or whether a change in status has occurred.
For each taxon reported, the place of discovery and if the sample is a specimen or more specimina (with deposited herbarium specimen or specimina), observatum or more observata (species observed growing in the wild) are also indicated.The following specific information on the collection or observation site(s) is also included: toponym (according to the "Geoportale Nazionale" [185], locality, municipality, province or metropolitan city (either of the latter two are indicated in parentheses only when they do not correspond to the name of the provincial municipality), geographical coordinates N and E (datum WGS84, UTM) and altitude.The metropolitan cities considered in this work are as follows: Bari, Cagliari, Catania, Firenze, Genova, Messina, Napoli, Palermo, and Reggio Calabria; all the others are provinces.Moreover, the growing environment(s), date of collection/observation, collector(s) (legit: leg.), observer(s) (observavit: obs.), author(s) of the identification (determinavit: det.).If the observer and the author of the identification are the same person, only "obs." is reported.If they are different persons, "obs." and "det." are reported.
In order to carry out a comparison across Italian regions, the percentage increase in alien taxa from 2010 to the present was evaluated, taking all Italian regions into consideration.To this end, the works carried out by several authors [27,43,58,[159][160][161] were considered and compared with the new data presented in this study.In addition, two indices were calculated: the Degree of floristic pollution (%), expressing the percentage of alien taxa in the total flora of the area (native + alien taxa, excluding those reported by mistake, doubtful species, data deficient, historical records, and extinct) and the Density alien taxa, expressing the ratio of the natural logarithm of the number of alien taxa to the natural logarithm of the surface of the examined area (Ln N. alien taxa/Ln km 2 ).For the surfaces of Italian administrative regions, reference is made to updated ISTAT data [186].

Conclusions
As many as 106 new taxa between first reports, status changes and extinctions for 11 of Italy's 20 administrative regions represent a significant increase in the number of alien species known to date for the Italian territory.Some of them also represent novelties for Italian and European territory.This study confirms the constant increase in alien species in the flora of the Italian territory: a common trend on a global scale.These results should further warn against biological invasions that still do not find a sufficient barrier to stop their advance.Floristic studies and field research such as this one and the others considered in this paper for the Italian territory demonstrate once again how knowledge of flora is a basic tool for biodiversity preservation.

Supplementary Materials:
The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/plants13050620/s1,Table S1: Record list of new alien taxa for Italian flora.
(d) To analyze the floristic similarities among the 20 administrative regions of Italy regarding allochthonous flora.(e) To analyze the trend of alien taxa in Italy from 2010 to 2023 and their influence on the overall floristic composition (natives + aliens) in the Italian territory.
A.Cunn.ex R.Br.Proteaceae-Neophyte-East Australia-Scapose phanerophyte First record for Calabria (casual alien) Specimen: 11 November 2021, quartiere Sant'Anna, Reggio Calabria, roadside/sidewalk, 38.101910 • N-15.643621 • E, 23 m a.s.l., leg.et det.V.L.A. Laface (REGGIO).Note.Numerous seedlings of G. robusta were observed along the roadside and on the sidewalks of the city center where several adult plants (3-4 years old) grow in the more open surrounding areas without city cleaning interventions.All the individuals observed derive from seeds of very large plants, used as street trees along the main road.

Table 1 .
New floristic records of alien taxa for the 12 Italian regions surveyed.

Table 2 .
Invasive status of the alien taxa recorded for the 12 Italian regions surveyed.

Table 4 .
Surface, percentage increase in alien taxa, degree of floristic pollution, and density of alien taxa in the 20 regions of Italy.