In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions for Italy or for Italian administrative regions. 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, 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).

Acer buergerianum Miq. subsp. buergerianum (Sapindaceae)

+ (CAS) TAA: Lavis (Trento), loc. Stazione di Lavis (WGS84: 46.147654°N, 11.099471°E), in una aiuola, 212 m, 14 August 2021, M. Simonazzi (FI, ROV). – Casual alien species new for the flora of Trentino-Alto Adige.

A few young individuals (height below 50 cm) were found in an urban flowerbed.

M. Simonazzi

Acer palmatum Thunb. (Sapindaceae)

+ (CAS) TAA: Tenna (Trento), loc. Visintainer, Biotopo “Pizè”, sponda del Torrente Vignola (WGS84: 46.0322870°N, 11.2620333°E), sponda torrentizia, 480 m, 25 April 2022, leg. N. Marchi, det. N. Marchi, M. Simonazzi (FI). – Casual alien species new for the flora of Trentino-Alto Adige.

An individual was found in the wild along the banks of the Vignola creek.

N. Marchi, M. Simonazzi

Acer tataricum L. subsp. ginnala (Maxim.) Wesm. (Sapindaceae)

+ (CAS) TAA: Levico Terme (Trento), loc. Someari, Biotopo “Le inghiaie”, sponda della roggia “La vena” (WGS84: 46.0006175°N, 11.3176637°E), sponda di roggia al margine del bosco, 436 m, 7 June 2021, leg. N. Marchi, det. M. Simonazzi, N. Marchi (FI, ROV). – Casual alien subspecies new for the flora of Trentino-Alto Adige.

A few individuals were found along the banks of the Vena creek.

N. Marchi, M. Simonazzi

Aesculus hippocastanum L. (Sapindaceae)

+ (CAS) PUG: Vico del Gargano (Foggia), loc. Mastrocianni (WGS84: 41.887860°N, 15.953290°E), margine stradale, 420 m, 29 August 2022, N. Biscotti, D. Bonsanto (FI). – Casual alien species new for the flora of Puglia.

N. Biscotti, D. Bonsanto

Aloë perfoliata L. (Asphodelaceae)

+ (CAS) SIC: Petrosino (Trapani), Torre Sibiliana (WGS84: 37.723575°N, 12.473320°E), arid garrigue, 2 m, 11 May 2022, G. Domina (FI, PAL). – Casual alien species new for the flora of Sicilia.

Some flowering individuals were observed.

E. Di Gristina, G. Barone

Bambusa vulgaris Schrad. ex J.C.Wendl. (Poaceae)

– ITALIA (SAR). – Alien species to be excluded from the flora of Italy (Sardegna).

Based on a review of the available literature, all the naturalized bamboo populations of Sardegna previously attributed to this species (Martinoli 1951; Camarda et al. 2016; Galasso et al. 2018; Calvia and Ruggero 2020) are to be attributed to Phyllostachys aurea Carrière ex Revière & C.Revière. Bambusa vulgaris ‘Vittata’ is cultivated in some gardens as ornamental.

A. Lallai, M. Sarigu

Bidens sulphurea (Cav.) Sch.Bip. (Asteraceae)

+ (CAS) BAS: Potenza (Potenza), Discesa San Gerardo (WGS84: 40.641315°N, 15.805873°E), bordo strada, 790 m, 15 September 2021, L. Rosati, G. Potenza (FI). – Casual alien species new for the flora of Basilicata.

We observed some flowering individuals.

G. Potenza

Calocedrus decurrens (Torr.) Florin (Cupressaceae)

+ (CAS) EMR: Modena (Modena), Cimitero di San Cataldo, tombe antiche sul lato S presso l’ingresso lato Piazza F. Setti (WGS84: 44.658293°N, 10.909558°E), angolo di terreno incolto coperto d’edera presso il muro di cinta, 35 m, 19 November 2022, F. Buldrini, C. Santini (FI). – Casual alien species new for the flora of Emilia-Romagna.

One individual, probably 3–5 years old (23-cm tall), grows in a shady place at about 40 m from the putative parent plants (four adult ornamental trees in a row).

F. Buldrini, C. Santini

Catalpa bignonioides Walter (Bignoniaceae)

+ (CAS) TOS: Siena (Siena), fiume canalizzato vicino all’area industriale (WGS84: 43.310626°N, 11.359643°E), 213 m, 29 July 2022, leg. T. Fiaschi, R. Fedeli, det. T. Fiaschi, S. Cannucci (FI, SIENA). – Casual alien species new for the flora of Toscana.

This species is similar to Catalpa ovata G.Don and C. speciosa Teas. According to Olsen and Kirkbride (2017), it differs from C. ovata by the leaf morphology (trilobate leaf blade in C. ovata vs entire in C. bignonioides). The differences between C. bignonioides and C. speciosa concern seed body dimensions and morphological aspects, i.e., 4.5–5.5×30–42 mm, with sides drawn out to an acute apex in C. bignonioides vs 5.5–7.5×26–31 mm, with sides drawn out to an obtuse apex in C. speciosa. Some young individuals and some fruiting ones were found.

T. Fiaschi, S. Cannucci

Cedrus atlantica (Endl.) G.Manetti ex Carrière (Pinaceae)

+ (CAS) LIG: Pornassio (Imperia), Colle di Nava, lungo la strada che dalla strada SS28 Nord porta al Forte Centrale (WGS84: 44.083667°N, 7.873605°E), muretto a secco che costeggia la strada, 943 m, 19 September 2022, M. Lonati, G. Nota (FI). – Casual alien species new for the flora of Liguria.

A young individual was found on dry-stone walls along a paved road near the Forte Centrale. Other individuals, about 30–40-cm tall, also grew on the walls of the Forte. These individuals were generated by adult Cedrus atlantica trees cultivated in the surroundings.

M. Lonati, G. Nota

Datura innoxia Mill. (Solanaceae)

– PIE. – Alien species to be excluded from the flora of Piemonte.

This species was reported for Piemonte by Abbà (1977, 1986), Correggia (2002), Rota and Cavallo (2005), and Lonati (2006). The specimens from Alba (Cuneo) and Baldissero d’Alba (Cuneo), cited by Abbà (1977, 1986) and preserved in ALBA (Pistarino et al. 1999), should be referred to Datura wrightii Regel (revision by A. Selvaggi, F. Rota, 25 November 2022). The specimens from Pocapaglia (Cuneo), cited by Rota and Cavallo (2005) and preserved in CBRA and ALBA, and the plant collected in 1879 by F. Craveri in Bra (Cuneo) and conserved in CBRA (Rota and Cavallo 2005) should be referred to D. wrightii (revision by F. Rota, 25 November 2022). The specimen from Viverone (Biella), cited by Lonati (2006) and preserved in TO, should also be referred to D. wrightii (revision by A. Selvaggi, 3 November 2022). The record by Correggia (2002) from Mondonio, in the municipality of Castelnuovo Don Bosco (Asti), has no linked specimens that can be verified and the epheremal populations recorded in 2002 are at present not confirmed. Moreover, the photo of the plant seen in this place seems to refer to D. wrightii. Consequently, Datura innoxia is excluded from the flora of Piemonte.

A. Selvaggi, F. Rota

Datura wrightii Regel (Solanaceae)

+ (CAS) VDA: Chambave (Aosta), ambienti ruderali a W della ex stazione ferroviaria (WGS84: 45.74418°N, 7.55635°E), ambiente ruderale, 468 m, 15 August 2022, A. Selvaggi (FI, AO). – Casual alien species new for the flora of Valle d’Aosta.

A. Selvaggi

Digitaria violascens Link (Poaceae)

+ (CAS) LIG: Santo Stefano di Magra (La Spezia), tra Falcinello (fraz. di Sarzana) e Ponzano Superiore (WGS84: 44.159202°N, 9.954352°E), bordo strada, 300 m, 21 September 2019, leg. S. Argenti, C. Argenti, det. C. Argenti, conf. F. Verloove (FI, Herb. C. Argenti). – Casual alien species new for the flora of Liguria.

Several individuals were found.

C. Argenti

Ehrharta erecta Lam. (Poaceae)

+ (CAS) LIG: Santo Stefano al Mare (Imperia), sulla costa (WGS84: 43.837915°N, 7.893002°E), spiaggia, 0 m, 21 March 2022, C. Bonifazio, S. Tripi (FI); Taggia (Imperia), Arma di Taggia, sulla costa (WGS84: 43.830717°N, 7.852751°E), spiaggia, 0 m, 8 April 2022, C. Bonifazio, S. Tripi (FI). – Casual alien species new for the flora of Liguria.

S. Tripi, C. Bonifazio

Eragrostis mexicana (Hornem.) Link subsp. virescens (J.Presl) S.D.Koch & Sánchez Vega (Poaceae)

+ (CAS) BAS: Viggiano (Potenza), Via Valloni 2^ Traversa (WGS84: 40.312842°N, 15.920795°E), a lato strada, 584 m, 20 September 2022, leg. et det. F. Santi, conf. E. Banfi (FI). – Casual alien subspecies new for the flora of Basilicata.

F. Santi

Gazania linearis (Thunb.) Druce (Asteraceae)

+ (CAS) CAM: Centola (Salerno), spiaggia a S di Torre dei Caprioli (WGS84: ca. 40.051801°N, 15.282958°E), spiaggia, 0 m, 17 March 1994, A. De Natale (Herb. A. De Natale No. 2904). – Casual alien species new for the flora of Campania.

According to the key published by Laguna Lumbreraras and Ferrer Gallego (2013), the specimens cited as Gazania rigens (L.) Gaertn. for Cilento by De Natale and Strumia (2007) are to be attributed to G. linearis.

E. Del Guacchio, A. De Natale

Impatiens parviflora DC. (Balsaminaceae)

+ (NAT) MAR: Arquata del Tronto (Ascoli Piceno), Pescara del Tronto, Parco Nazionale del Gran Sasso e Monti della Laga, lungo la sponda destra del Fiume Tronto (WGS84: 42.74840636°N, 13.27191404°E), megaforbieto ripariale, 660 m, 8 September 2022, F.M. Tardella, R. Pennesi, R. Vetromile (FI, CAME). – Naturalized alien species new for the flora of Marche.

The species can be found sporadically along the banks of the Tronto river.

F.M. Tardella, R. Vetromile

Jasminum nudiflorum Lindl. (Oleaceae)

+ (CAS) PUG: Vico del Gargano (Foggia), centro storico (WGS84: 41.919412°N, 15.920386°E), in sacche di terra su roccia, 442 m, 21 February 2022, D. Bonsanto, N. Biscotti (FI). – Casual alien species new for the flora of Puglia.

D. Bonsanto, N. Biscotti

Oenothera speciosa Nutt. (Onagraceae)

+ (CAS) ABR: Chieti (Chieti), quartiere Chieti Scalo, Via Pescasseroli (WGS84: 42.362654°N, 14.144006°E), incolto al margine della strada, ambiente urbano con vegetazione sinantropica, 38 m, 5 May 2022, A. Pica, J. Lupoletti (FI). – Casual alien species new for the flora of Abruzzo.

The species covered about 30 m².

A. Pica, J. Lupoletti

Opuntia microdasys (Lehm.) Pfeiff. (Cactaceae)

+ (NAT) UMB: Arrone (Terni), fraz. Casteldilago, rupe inaccessibile sotto il paese (WGS84: 42.578190°N, 12.759101°E), rupe, 235 m, 30 October 2021, F. Lucchese (photo in FI). – Naturalized alien species new for the flora of Umbria.

F. Lucchese, G. Ratini

Opuntia monacantha Haw. (Cactaceae)

+ (CAS) UMB: Arrone (Terni), fraz. Casteldilago, rupe inaccessibile sotto il paese (WGS84: 42.578090°N, 12.759189°E), rupe, 252 m, 30 October 2021, leg. F. Lucchese, det. A. Guiggi (photo in FI). – Casual alien species confirmed for the flora of Umbria.

Opuntia monacantha was previously reported as doubtfully occurring in Umbria (Galasso et al. 2018), but this record turned out to be never published. The plants are mixed with many individuals of O. humifusa (Raf.) Raf.

F. Lucchese, G. Ratini

Opuntia stricta (Haw.) Haw. (Cactaceae)

+ (INV) UMB: Terni (Terni), loc. Le Pisciarelle (WGS84: 42.604104°N, 12.611363°E), pendio pietroso in radura boschiva con leccio e Pinus halepensis, 400 m, 17 October 2022, leg. P. Ratini, det. A. Guiggi (FI). – Invasive alien species new for the flora of Umbria.

Opuntia stricta was observed also in other localities in the province of Terni: Arrone, fraz. Casteldilago (WGS84: 42.578090°N, 12.759189°E); Amelia, fraz. Fornole (WGS84: 42.539353°N, 12.459980°E, and 42.541411°N, 12.465183°E); Amelia, fraz. Sambucetole (WGS84: 42.596905°N, 12.435835°E). This species invades terraces of former olive groves, holm oak clearings, natural cliffs, and artificial escarpments. In the locality upstream of Fornole, about 31 ha are covered by it. In the locality of Le Pisciarelle, it may have hybridized with O. humifusa (Raf.) Raf. with which it shares the same habitat.

F. Lucchese, G. Ratini

Paspalum denticulatum Trin. (Poaceae)

+ (NAT) ITALIA (LOM): Milano (Milano), Largo Cairoli, aiuola attorno al monumento in centro alla piazza (WGS84: 45.468240°N, 9.182434°E), tappeto erboso, 124 m, no exp., 5 July 2021, leg. G. Galasso, det. E. Banfi (MSNM No. 51237 sub P. dilatatum); ibidem, 21 September 2021, leg. G. Galasso, det. E. Banfi (MSNM No. 51238 sub P. dilatatum); ibidem, Via Monte Cimone, spartitraffico alberato (WGS84: 45.450573°N, 9.226346°E), tappeto erboso, 109 m, no exp., 20 November 2022, E. Banfi (FI, MSNM barcode MSNM52201). – Naturalized alien species new for the flora of Italy (Lombardia).

This species is native to central-southern America, and shows a high diversity; it belongs to a group of four taxa, treated as synonyms by Zuloaga and Morrone (2005) and by Denham et al. (2010), the best known of which is Paspalum lividum Trin. ex Schltdl. The latter name was adopted by Allen and Hall (2003) in the treatment of Flora of North America. In any case, even keeping the two species separate, our find fits better with P. denticulatum on morphological grounds, especially regarding the width of the leaf blade (up to 9 mm).

E. Banfi, G. Galasso

Perilla frutescens (L.) Britton (Lamiaceae)

+ (CAS) CAM: Napoli (Napoli), Via M. Pietravalle (WGS84: 40.868711°N, 14.226402°E), bordo strada, 251 m, 21 June 2020, leg. R. Motti, det. A. Cozzolino, R. Motti (FI, PORUN). – Casual alien species new for the flora of Campania.

R. Motti, A. Cozzolino

Petunia axillaris (Lam.) Britton, Sterns & Poggenb. (Solanaceae)

+ (CAS) SIC: Palermo (Palermo), Via Imera (WGS84: 38.117153°N, 13.348883°E), negli interstizi dei marciapiedi, 30 m, 16 July 2021, leg. E. Di Gristina, det. E. Di Gristina, G. Domina (FI). – Casual alien species new for the flora of Sicilia.

Petunia axillaris is an annual herbaceous plant native to temperate southern America, caracterized by a hypocraterimorph white corolla, with a sub-terete tube (Flora e Funga do Brasil 2023 [onwards]). Some mature individuals have been found.

E. Di Gristina, G. Barone

Physalis philadelphica Lam. (Solanaceae)

+ (CAS) ABR: Scafa (Pescara), loc. Decontra (WGS84: 42.239886°N, 14.025695°E), margine stradale nei pressi di una cava di gesso caratterizzato da vegetazione ruderale, 216 m, 16 October 2021, J. Lupoletti, A. Pica (FI). – Casual alien species new for the flora of Abruzzo.

A single specimen was observed.

J. Lupoletti, A. Pica

Ruellia simplex C.Wright (Acanthaceae)

+ (CAS) SIC: Palermo (Palermo), lungo Corso Tukory (WGS84: 38.108403°N, 13.357091°E), aiuola e bordo strada, 30 m, 6 July 2022, E. Bajona (FI, PAL). – Casual alien species new for the flora of Sicilia.

In Sicilia, Ruellia simplex spreads spontaneously also in the Botanical Garden of Palermo, where it grows in some pots and flowerbeds, near the cultivated specimen.

E. Bajona

Saxifraga stolonifera Curtis (Saxifragaceae)

+ (CAS) PIE: Mergozzo (Verbano-Cusio-Ossola), nei pressi di Via Nostrani Celso (WGS84: 45.959391°N, 8.448122°E), terrazzamento incolto e muretti a secco adiacenti alla strada, 218 m, 6 September 2021, M. Pittarello, D. Barberis (FI). – Casual alien species new for the flora of Piemonte.

The species has colonized an area of a few square meters.

M. Pittarello, D. Barberis

Solanum nitidibaccatum Bitter (Solanaceae)

+ (NAT) LOM: Acquanegra Cremonese (Cremona), Via Crotta D’Adda (WGS84: 45.163122°N, 9.887033°E), campo con stoppie di mais, 42 m, no exp, 31 October 2022, F. Bonali (FI, Herb. F. Bonali). – Naturalized alien species new for the flora of Lombardia.

Numerous individuals are present in three contiguous fields.

F. Bonali

Tulbaghia violacea Harv. (Amaryllidaceae)

+ (CAS) LIG: Pietra Ligure (Savona), scogli di retrospiaggia presso il confine con Loano (WGS84: 44.139524°N, 8.269283°E), rupi costiere con accumulo di sabbia, 5 m, no exp., 30 August 2022, G. Galasso (FI, MSNM barcode MSNM52197). – Casual alien species new for the flora of Liguria.

A single small tuft was observed.

G. Galasso, E. Banfi

Nomenclatural, status, and distribution updates according to Abbà (1977), Applequist (2023), Bonali (2023), Brusa (2022), Cambria et al. (2023), Carrega and Silla (1999), Conti and Bartolucci (2023), Conti and Giacanelli (2023), Conti et al. (2023), Denham et al. (2010), Di Pietro et al. (2022), Galasso (2009, 2023), Ganz (2022), Ganz et al. (2022a, 2022b), Gariboldi (2022), Iamonico and Bovio (2023), IPNI (2022 [onwards]), Manzi and Truzzi (2023), Martínez-González et al. (2022), Peruzzi (2023), POWO (2022 [onwards], 2023 [onwards]), Prosser et al. (2022), Sennikov et al. (2023), Simonazzi and Truzzi (2023), Tropicos (2022 [onwards]), Viegi and Cela Renzoni (1981), Villa et al. (2022), and Wilson (2022), and corrections to Galasso et al. (2018) and subsequent updates summarised in the Portal to the Flora of Italy (2023) are provided in Suppl. material 1.

G. Galasso, F. Bartolucci

We gratefully acknowledge Pablo P. Ferrer-Gallego who confirmed the identification of Gazania linearis, Alessandro Guiggi who identified the specimens of Opuntia monacantha and O. stricta, Laura Guglielmone and Gianni Repetto for the help in consulting herbariums TO and ALBA respectively, and Maurizio Bovio, Franco Correggia, Daniela Longo and Lorenzo Peruzzi who provided informations on distribution.