In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, exclusions, and status changes from casual to naturalized or invasive for Italy or for Italian administrative regions for taxa in the genera Acacia, Akebia, Allocasuarina, Aloë, Brachychiton, Convolvulus, Freesia, Gleditsia, Hesperocyparis, Kalanchoë, Liriope, Mazus, Melia, Phyla, Platycladus, Prunus, and Retama. Nomenclatural and distribution updates, published elsewhere, and corrections are provided as Suppl. material 1.

Alien species, floristic data, Italy, nomenclature

The text for the new records, status changes from casual to naturalized or invasive, exclusions, and confirmations should be submitted electronically to Lorenzo Lastrucci (lorenzo.lastrucci@unifi.it). The corresponding specimen along with its scan or photograph has to be sent to FI Herbarium: Museo di Storia Naturale (Botanica), Sistema Museale di Ateneo, Via G. La Pira 4, 50121 Firenze (Italy). Those texts concerning nomenclatural novelties and typifications (only for accepted names) should be submitted electronically to Gabriele Galasso (gabriele.galasso@comune.milano.it). Each text should be within 1,000 characters (spaces included).

Acacia melanoxylon R.Br. (Fabaceae)

+ (INV) ITALIA (SAR): San Teodoro (Gallura Nord-Est Sardegna), Monte Nieddu (WGS84: 40.750272°N, 9.589148°E), invasiva in ambiente ripariale, 370 m, 15 July 2024, M. Fois, A. Cuena-Lombraña (FI, CAG). – Status change from naturalized to invasive alien for the flora of Italy; status change from casual to invasive alien for the flora of Sardegna.

Despite being recently reported as a casual alien (Galasso et al. 2024), this species has to be considered invasive in Sardegna. Several individuals, in all life stages, have been observed spreading in some natural environments, especially under humid and shady conditions, in Rio Leni (Villacidro, Sud Sardegna province), Monte Arci (Pau, Oristano province), Monte Nieddu (San Teodoro, Gallura Nord-Est Sardegna province), and Berchida (Siniscola, Nuoro province).

M. Fois, A. Cuena-Lombraña

Akebia quinata (Thunm. ex Houtt.) Decne. (Lardizabalaceae)

+ (NAT) ITALIA (TAA): Castelnuovo (Trento), scarpata incolta al margine setten­trionale della strada che collega la loc. Spagolle (Castelnuovo) con Via G. Gozzer (Borgo Valsugana), a E del ponte che attraversa il Torrente Moggio (WGS84: 46.05056°N, 11.47202°E), scarpata incolta, 380 m, SSE, 14 April 2024, leg. F. Valentini, D. Boker, L.M. Boker, det. F. Valentini (FI, TR). – Status change from casual to naturalized alien for the flora of Italy (Trentino-Alto Adige).

Akebia quinata was previously reported as a casual alien in Trentino-Alto Adige by Wilhalm (2011). This new population was first seen in 2023. It consists of a large population, with individuals growing from the soil to the upper part of the trees. In 2024 numerous flowering individuals were detected.

F. Valentini, D. Boker

Allocasuarina verticillata (Lam.) L.A.S.Johnson (Casuarinaceae)

+ (NAT) ITALIA (SAR): Domus de Maria (Sud Sardegna), antica strada romana (WGS84: 38.909013°N, 8.899185°E), naturalizzata nella macchia, 81 m, 5 May 2024, A. Lallai, M. Sarigu, L. Podda (FI, CAG). – Status change from casual to naturalized alien for the flora of Italy (Sardegna).

This species was introduced in Sardegna in the second half of the 19^th century (Gennari 1874) and has been used as an ornamental tree in urban greenery and for reforestation in degraded contexts. The area where the species was found has been subject to reforestation by the Regional Forestry Agency since the end of the 1950s to the 1970s with several non-native species, such as Acacia saligna (Labill.) H.L.Wendl., A. pycnantha Benth., and Brachychiton populneus (Schott & Endl.) R.Br. The population recorded here covers a surface of about 100 m², each with at least fifty individuals, including adults, juveniles, and seedlings, arranged in two groups of individuals. Accordingly, Allocasuarina verticillata is to be considered naturalized.

A. Lallai, M. Sarigu

Aloë microstigma Salm-Dyck subsp. microstigma (Asphodelaceae)

+ (NAT) ITALIA (SIC): Lampedusa e Linosa (Agrigento), Isola di Lampedusa, Cala Francese (WGS84: 35.496217°N, 12.626316°E), rocky uncultivated land, 10 m, 20 March 2024, G. Domina (FI, SAF). – Naturalized alien species new for the flora of Italy (Sicilia).

This species is native to Cape Province (South Africa), and is used in horticulture as low maintenance garden plant. The new population probably comes from maintenance pruning remains from nearby houses. An additional population of a few individuals has been observed in Favignana (Trapani province) at Cala del Passo, 30 m a.s.l. on a cliff overhanging the sea. Plant samples were identified according to Klopper et al. (2023).

G. Barone, G. Domina

Brachychiton populneus (Schott & Endl.) R.Br. (Malvaceae)

+ (NAT) ITALIA (SAR): Domus de Maria (Sud Sardegna), antica strada romana (WGS84: 38.913738°N, 8.907798°E), naturalizzata nella macchia, 30 m, 5 May 2024, L. Podda, G. Bacchetta (FI, CAG). – Status change from casual to naturalized alien for the flora of Italy (Sardegna).

Since the first report in 2018 (Ruggero et al. 2024), several individuals of various ages have been observed naturalized within the coastal scrub vegetation together with other non-native species (Allocasuarina verticillata [Lam.] L.A.S.Johnson, Acacia saligna [Labill.] H.L.Wendl., and A. pycnantha Benth.) in an area subjected to reforestation by the Regional Forestry Agency until the 1970s.

L. Podda, G. Bacchetta

Convolvulus tricolor L. subsp. tricolor (Convolvulaceae)

− CAM. – Alien species to be excluded from the flora of Campania.

The individuals reported as Convolvulus tricolor s.l. from the Phlegrean Fields (Napoli province) (Terracciano 1917) are to be referred to C. tricolor subsp. cupania­nus (Tod.) Cavara & Grande (Bartolucci et al. 2024). The plants from the island of Capri (Cerio 1939) were described as intermediate between the same native subspecies and the autonym, non-native, subspecies. As Cerio (1939) was not able to assess if the plant was escaped or indigenous, and no specimen collected by him is available (Herbarium I. Cerio, pers. obs.), C. tricolor subsp. tricolor is to be excluded from the flora of Campania.

E. Del Guacchio, A. De Luca

Freesia leichtlinii Klatt subsp. alba (G.L.Mey.) J.C.Manning & Goldblatt (Iridaceae)

+ (NAT) SIC: Castellammare del Golfo (Trapani), Monte Inici, Contrada Belvedere (WGS84: 38.030211°N, 12.873714°E), side road, 190 m, 16 March 2024, R. Rocca (FI). – Status change from casual to naturalized alien for the flora of Sicilia.

In Sicilia, this species was previously reported as a casual alien. The report of Freesia refracta (Jacq.) Eckl. ex Klatt on the Island of Pantelleria (Domina and Mazzola 2008) refers to this taxon. In Castellammare del Golfo we observed an abundant population, comprising numerous individuals of various ages, many seeding, extending along the road, spanning approximately 50 m². Not far from the main population two smaller nuclei were observed, less than 1 km away. Similarly, another population consisting of several dozens of individuals on a road embankment on the road SS514, in southeastern Sicilia (Chiaramonte Gulfi, Ragusa province, WGS84: 37.057117°N, 14.649669°E) was observed.

R. Rocca, G. Barone

Gleditsia triacanthos L. (Fabaceae)

+ (NAT) MOL: Campobasso (Campobasso), poco a S di Via Campania (WGS84: 41.557252°N, 14.677393°E), lungo un sentiero, 657 m, 8 May 2024, P. Fortini, L. Quaranta (FI, IS). – Naturalized alien species new for the flora of Molise.

Around 10 individuals approximately 10–12 m tall were found along the path in a peripheral area of Campobasso. At least five individuals are mature and abundantly producing fruit and a notable renewal of young plants has been observed all around.

P. Fortini, L. Quaranta

Hesperocyparis arizonica (Greene) Bartel (Cupressaceae)

+ (NAT) UMB: Orvieto (Terni), nei pressi del Pozzo di San Patrizio (WGS84: 42.722664°N, 12.120481°E), pareti rocciose verticali che dalla città digradano verso il basso, 260 m, 11 February 2024, G. Marengo, M. Lonati (FI). – Status change from casual to naturalized alien for the flora of Umbria.

This species grows in vertical cliffs near the urban area of Orvieto, and probably has originated from individuals cultivated in the nearby urban parks. The population is stable, consisting of several shrubby and fruit-bearing individuals.

G. Marengo, M. Lonati

Kalanchoë × houghtonii D.B.Ward (Crassulaceae)

+ (NAT) SIC: Palermo (Palermo), Monte Pellegrino, W slope (WGS84: 38.158301°N, 13.345287°E), pine grove, 70 m, 14 April 2024, R. Rocca (FI). – Status change from casual to naturalized alien for the flora of Sicilia.

This nothotaxon was first reported as a casual alien in Sicilia in 2017 (Di Gregorio et al. 2017). We observed an expanding population in Monte Pellegrino, reproducing both sexually and through leaf propagules. Two additional populations were recorded: one on a cliff in the harbour of Terrasini (Palermo province, WGS84: 38.15599°N, 13.08188°E), the other in Palermo along the motorway spur route connecting to Tommaso Natale/Sferracavallo (WGS84: 38.191133°N, 13.283020°E). In 2017, numerous individuals of Kalanchoë × houghtonii were observed on the roofs of the historic center of Palermo (G. Galasso pers. comm).

R. Rocca, G. Barone

Liriope spicata (Thunb.) Lour. (Asparagaceae)

+ (NAT) SAR: Senorbì (Sud Sardegna), loc. Funtana ‘e Canna (WGS84: 39.541880°N, 9.134429°E), area ruderale, 202 m, July 2024, I. Orrù, F. Mascia (FI). – Naturalized alien species new for the flora of Sardegna.

Individuals of the species have been found in ruderal areas, along the edges of the railroad, and originated from dispersed propagules of plants that were cultivated over 10 years ago in the garden of a cantonment house and no longer present today.

I. Orrù, F. Mascia

Mazus pumilus (Burm.f.) Steenis (Mazaceae)

+ (NAT) EMR: Parma (Parma), Basilica di Santa Maria della Steccata (WGS84: 44.802658°N, 10.327379°E), tra le fessure del selciato, 53 m, 1 July 2024, M. Adorni, A. Alessandrini (FI). – Naturalized alien species new for the flora of Emilia-Romagna.

M. Adorni, A. Alessandrini

Melia azedarach L. (Meliaceae)

+ (NAT) SAR: Oristano (Oristano), strada SP56 (WGS84: 39.92388°N, 8.58032°E), incolto, substrato sabbioso, presente lungo i bordi stradali, 9 m, 29 July 2024, leg. V. Lozano, G. Brundu, det. G. Brundu (FI, Herb. Uniss Agraria). – Status change from casual to naturalized alien for the flora of Sardegna.

The species was observed also in: Selargius (Cagliari) (WGS84: 39.253887°N, 9.173048°E), uncultivated land, 10 m, 9 June 2024, L. Podda; San Vito (Sud Sardegna), road SS125 ‘Orientale Sarda’ (WGS84: 39.520588°N, 9.595178°E), roadside, 8 m, 15 June 2024, L. Podda; Cagliari (Cagliari), Viale G. Marconi (WGS84: 39.243090°N, 9.152730°E), roadside, 6 m, 5 July 2024, L. Podda; Oristano (Oristano), road SP81, Viale Repubblica 23 (WGS84: 39.90775°N, 8.56968°E), roadside, 9 m, 29 July 2024, V. Lozano, G. Brundu. The observed individuals probably originated from plants cultivated as ornamentals in adjacent gardens. In recent years, we have observed several naturalized adult individuals and seedlings in ecosystems subject to anthropogenic disturbance including the southern (particularly Campidano), central eastern (Sarrabus and Ogliastra) and central western parts (Oristano) of Sardegna.

V. Lozano, L. Podda

Phyla canescens (Kunth) Greene (Verbenaceae)

+ (NAT) LOM: Gerenzano (Varese), Via R. Lepetit 34 (WGS84: 45.632838°N, 8.966914°E), verde curato all’interno dell’Insubrias BioPark, 227 m, 28 September 2016, E. Meneguzzo (FI, Herb. E. Meneguzzo). – Status change from casual to naturalized alien for the flora of Lombardia.

In recent years this population of Phyla canescens has expanded to occupy an area of approximately 200 m².

Enzo Meneguzzo, Nicola M.G. Ardenghi

Platycladus orientalis (L.) Franco (Cupressaceae)

+ (NAT) TAA: Merano (Bolzano), loc. Quarazze (WGS84: 46.684801°N, 11.149760°E), vegetazione sinantropica di recupero delle scarpate e delle aree più disturbate della vegetazione forestale, 365 m, 8 March 2024, leg. G. Mei, E. Grande, det. G. Mei, A. Stinca (FI, Herb. G. Mei). – Status change from casual to naturalized alien for the flora of Trentino-Alto Adige.

The discovery of a population characterized by individuals of different ages, renewal and seedlings in the municipality of Merano, highlights how the species has now become naturalized in Trentino-Alto Adige.

G. Mei, A. Stinca

Prunus amygdalus Batsch (Rosaceae)

+ (NAT) SAR: Quartu Sant’Elena (Cagliari), loc. Simbirizzi, incolti del lago (WGS84: 39.264670°N, 9.197378°E), naturalizzata negli incolti, 47 m, 25 July 2024, G. Calvia, F. Mascia, G. Bacchetta (FI, CAG). – Status change from casual to naturalized alien for the flora of Sardegna.

This species has been cultivated throughout the island since a long time, exhibiting little to no tendency to become wild. At most, it would often spread around the planted trees through vegetative propagation. However, in recent years we have observed adult and subadult specimens in areas far from old plantations, with regeneration occurring through seed propagation as well. This naturalization has been noted in several areas of the island, including both the southern (particularly Campidano and Marmilla) and northern (Logudoro and Mejlogu) parts.

G. Calvia, F. Mascia

Retama monosperma (L.) Boiss. subsp. monosperma (Fabaceae)

+ (NAT) ITALIA (LIG): Ventimiglia (Imperia), fraz. Latte, lungo la strada SS1 Aurelia (WGS84: 43.795199°N, 7.571592°E), margine della strada, negli interstizi del muro di contenimento, 37 m, 20 February 2024, M. Lonati, G. Nota (FI). – Status change from casual to naturalized alien for the flora of Italy (Liguria).

The species colonizes uncultivated fields and abandoned terraces in the area between Latte and Bordighera (Imperia province), also settling in cracks of walls and sidewalks of urban infrastructures.

M. Lonati, G. Nota

Nomenclatural, status, and distribution updates according to Negri (1943), Schroeder (1972), Roma-Marzio et al. (2016), Paton et al. (2019), Moroni and O’Leary (2020), Knapp and Naczi (2021), Alterio et al. (2023), Jesus et al. (2023), Andreone and Guazzone (2024), Antonietti and Dellavedova (2024a, 2024b), Antonietti et al. (2024a, 2024b, 2024c), Bajona et al. (2024), Bonivento et al. (2024), Borghesan et al. (2024), Brusa (2024), Chepinoga et al. (2024), Đurović et al. (2024), Elvebakk and Bjerke (2024), Fiaschi et al. (2024), Freire et al. (2024), Missouri Botanical Garden (2024 [onwards]), Pascale (2024), Pasta and Badalamenti (2024), Picco and Deandrea (2024), POWO (2024a [onwards], 2024b [onwards], 2024c [onwards], 2024d [onwards], 2024e [onwards], 2024f [onwards], 2024g [onwards], 2024h [onwards]), 2024i [onwards]), Roma-Marzio et al. (2024), Röser and Tkach (2024), Rota and Olivero (2024), Selvaggi and Dellavedova (2024), Sukhorukov et al. (2024), Verloove et al. (2024), Pasta et al. (2025), and corrections to Galasso et al. (2024), available at the Portal to the Flora of Italy (2024), are provided in Suppl. material 1.

G. Galasso, F. Bartolucci

We gratefully acknowledge the Acta Plantarum staff, Enrico Banfi, Lorenzo Peruzzi, Francesco Roma-Marzio, Rizzieri R. Masin, and Alberto Selvaggi who provided useful information.