In this study, we compared current data and data of the census made in the 1990s related to the vascular flora of Capo Mortola (Ventimiglia, Italy), considering 270 taxa not dependent on crop management. The current status reported 198 alien species: 5 invasive, 65 naturalized 75 casual, 38 occurring as casual in human-dominated systems, but without direct intervention by humans and not close to parent plant, 15 occurring as casual alien, but still with some uncertainties for a definitive classification, and plus 3 cryptogenic and 1 eradicated (extinct) taxa, while in 1996 were 229 species: 87 naturalized and 142 adventitious (casual). Of these, 40 taxa show an increasing trend and 41 a decreasing or disappearing trend. If we consider the wild areas of Capo Mortola, 10 taxa are new to the Italian flora (7 casual and 3 naturalized) while 13 are new to the Ligurian flora only (all casual). If we also consider the neglected areas of the Botanical Gardens, 18 new casual species for the Italian flora and 10 for the Ligurian one would be added. In addition, 9 status changes are proposed on a national scale and 17 on a regional scale. An in-depth analysis was conducted on the presence and the local history of a subset of 34 exotic plants, 11 of which are new or have a new status for the Italian flora.

Exotic taxa, flora, invasive alien species, Italy, Liguria

The Italian exotic flora has been the subject of numerous studies. It has received increasing attention in recent decades due to the awareness of the threat that invasive alien species represent for biodiversity. In the neighbouring France, Sant and Alziar (2013) reconstructed the changes in the flora of the hill of the Château de Nice, an area of about 10 ha with natural, historical and landscape value, with reference to patrimonial taxa, rare, exotic or invasive, starting from 1840. For the alien species, these authors have developed comparisons starting from the study of Fritz Mader (1909). He was the first botanist to introduce the floristic invasions problem along the coastal strip, including the Riviera Ligure and the Côte d’Azur, where gardens and plant collections have reached their highest levels since the second half of the 19^th century. These areas are highly vulnerable to plant invasion risk. In southeastern France, Ducatillion et al. (2015) assembled useful data for the invasion risk evaluation: out of 400 species planted initially in an arboretum, only 13 are naturalized. More recently, a working group coordinated by Cottaz (2020) updated the list of invasive species in the region Provence-Alpes-Côte d’Azur (PACA), now including 298 taxa. De Vilmorin (1950) published a report on the exotic flora acclimated on the Côte d’Azur that helps us to understand how various acclimated species of that period are today naturalized or invasive.

In Italy, the checklist of Galasso et al. (2018a) – and its subsequent updates (Galasso et al. 2018b, c, 2019a, b, 2020a, 2020b, 2021a, b) – constitutes the reference document for the records that are regularly reported in this journal. However, during the elaboration of this checklist, no information was available about the extreme western part of Liguria, close to the Italian-French border including the Giardini Botanici Hanbury (GBH) and their immediate surroundings. Probably, these authors did not report the taxa occasionally escaped from botanical gardens and private gardens. However, about half (over 10 ha) of the GBH compendium at Capo Mortola is covered by many natural habitats (such as cliffs, mixed woods, pine forests, garrigues, scrubs, arid grasslands, reeds, dry stone walls, ruins, etc.) harbouring a large number of naturalized species. Campodonico (2008) already highlighted the naturalization of many exotic species in the Riviera di Ponente and the fact that they spread “mainly via fertile seed dispersal by wind, water, birds, and mammals, as well as voluntary or unintentional human interventions”. Recently, some authors (Guadagni et al. 2013) reported the presence of naturalized exotic species in the same area as new records, but these were already recorded in different editions of the Hanbury plant checklist.

By examining the publications and manuscripts related to this area, it is possible to reconstruct the story (introduction and naturalization process) of many exotic species in neighbouring natural and semi-natural habitats, leading to a significant increase in the checklist mentioned before. The main purposes of this report are four: I) to list the alien taxa recently found in Capo Mortola and its immediate surroundings (Fig. 2); II) to verify the categories attributed to the exotic species growing spontaneously and already reported in the last catalogue (Campodonico et al. 1996) 25 years later; III) try to understand the changes that have taken place in the exotic flora over the course of about 25 years; IV) to highlight the species new to Italy and Liguria according to the present Italian checklist (Galasso et al. 2018a).

Capo Mortola is a promontory on the western coast of Liguria, in the municipality of Ventimiglia, a few kilometers from the French border (Fig. 1). It includes a Regional Protected Area of about 20 ha and the western part of the Special Area of Conservation (SAC) “Capo Mortola” of about 50 ha. This SAC extends from sea level up to 260 m a.s.l. and its geographical limits have the following coordinates: 43°46'45.0"N, 7°32'32.7"E and 43°47'21.2"N, 7°33'30.1"E.

Figure 1. 

The location of the study area.

The study area includes the entire surface of the compendium of the GBH: about half of this compendium is dominated by natural and semi-natural habitats such as cliffs, mixed woods, pine forests, garrigues, scrubs, arid grasslands, reeds, dry stone walls, ruins, and the remaining part is cultivated as a garden (with exotic plant collections), but it also includes some natural sectors subject to minimal gardening activities (mowing). A cycling / pedestrian path that follows the ancient Roman road runs in a trench outside the botanical gardens, cutting the compendium in two from east to west. The study area is represented within the brown line in Fig. 2 and includes the inhabited area of Mortola Inferiore and the natural or cultivated areas outside the GBH, located to the west, north and east of these. Fig. 2 shows the map of the vegetation and land use of the study area; Fig. 3 shows some examples of the natural and semi-natural habitats of the study area.

Figure 2. 

Vegetation and land use of the study area. 1: discontinuous communities of sea cliffs, seashores and bare rocks; 2: arid grasslands, garrigues and scrubs; 3: holm oak bushes; 4: forests dominated by pines; 5: settled areas (including roads, and greenhouses); 6: agricultural mosaic, with cultivated garden, dry stone walls, paths and semi-natural or abandoned areas; 7: olive groves; 8: riparian woods; 9: reed. The study area is bounded by the coastline and falls within the brown line. The red line marks the western part of the SAC.

Figure 3. 

Examples of the natural and semi-natural habitats of the study area. Above: cliff and scrub; below: riparian forest and pine forest.

The study area has a Mediterranean pluviseasonal oceanic bioclimate with upper thermomediterranean thermotype and dry ombrotype (Rivas Martínez et al. 2011; Pesaresi et al. 2014, 2017), with an average annual temperature of ca. 16 °C and an average annual rainfall of ca. 800 mm. The driest month is July (18 mm), while November is the rainiest month with an average of 121 mm; the average temperature in the hottest month of the year (July) is 23.3 °C while the average temperature during the coldest month (January) is 9.2 °C. The area has passed through several changes over the last centuries; in the lower portion it is still possible to see a stretch of the ancient Roman road, Via Iulia Augusta. The superficial hydrographical network is characterized by the lower half of the Vallone della Sorba stream; the acclivity is around 45% in the upper portion and on the western side of the Cape, which decreases in the lower portion up to values of just over 10% and with sub-flat zones. The two sides of the syncline of Capo Mortola are very well exposed with bioclastic limestones (Capo Mortola Calcarenites) while the core of the grey blue marls (Olivetta San Michele Silty Marls) have almost completely been obliterated by several terraces. Along the north side of the area some weakly cemented yellowish sands are detected (Faccini et al. 2015). A more detailed description of the area is available in the illustrative report of the SAC management plan adopted in 2016 (Mariotti et al. 2016).

The GBH were created starting from 1867 by the supervision of its founder Sir Thomas Hanbury (1832–1907), who bought the building and the surrounding areas with the goal to acclimate species of rare plants and plants with high pharmacological interest coming from warm-temperate regions all over the world. He was supported by his brother Daniel Hanbury (1825–1875), pharmacologist and botanist, and by Ludwig Winter (1846–1912), a German botanist and landscape architect. Scientific activities began in 1880. The GBH, the regional protected area and the SAC Capo Mortola are currently managed by Università degli Studi di Genova. The progression and changes in the plant collections are the result of intense exchanges and purchases made by Thomas and the curators of the botanical gardens who followed one another, in particular Gustav Cronemeyer (?1832–1892), Kurt Dinter (1868–1945) and especially, Alwin Berger (1871–1931), during the first phase of the history of the gardens, which ended in 1907 with Thomas’s death (Mariotti and Minuto 2017). Even in the subsequent phases, under the care of Thomas’ son, Cecil, and daughter-in-law Dorothy, and during the post-war recovery initially curated by Onorato Masera and, later, by the curators and directors of the Università degli Studi di Genova (Pier Giorgio Campodonico, Salvatore Gentile, Paola Profumo and others) the collections had fluctuating trends, with significant new entries and losses of species and varieties (Campodonico et al. 1999a, b; Zappa and Campodonico 2005, 2006, 2007; Campodonico and Zappa 2006; Zappa et al. 2010, 2011, 2014, 2019; Mariotti and Zappa 2015). Evidence of these changes can be found in the plant catalogues (Cronemayer 1889; Dinter 1897; Berger 1912; Ercoli and Lorenzi 1938; Campodonico et al. 1996), various editions of the Index Seminum (compiled by various authors from 1880 to 1939) and Sowing & Planting manuscripts (Zappa 2011; Zappa et al. 2019). Further information on the flora of Capo Mortola can be found in various publications (Berger 1905; Campodonico 1992; Gentile and Gentile 1994; Campodonico et al. 1999a, b; Zappa and Campodonico 2005, 2006, 2007; Blardoni 2016).

The compendium of GBH is an area of about 20 ha, which is continuously monitored. Not only the flora, but also meteorological data have long been collected and recently processed (Vagge et al. 2019). Native taxa and taxa whose presence is determined by direct human management were not considered here. We only considered alloctonous taxa with an autonomous reproduction and development at a distance from the cultivated parent plant, with particular regard to those that have settled in natural and semi-natural habitats. They are mainly represented by mixed woods, scrubs and garrigues of the Vallone della Sorba, by mown lawns near the sea and by stone walls of the terraces and the edges of the Roman road. Furthermore, inside the 9 ha indicated as Garden, there are many areas without any cultivation activities; species growing exclusively in areas maintained with cultivation activities were not considered. The search for alien plants was then extended outside the GBH on a surrounding area of about 15 ha, including settlements, agricultural areas and paths, albeit with some difficulties caused by the fencing of private spaces. For the compendium, the comparison is based on the catalogue published 25 years ago by Campodonico et al. (1996), who used the following categories: acclimated (ACCL), assisted (ASS), adventive (ADV), cultivated (CULT), established / naturalized (Sptnzz./NAT), native/spontaneous (Spt./NATIVE). The meaning of these terms was defined by Campodonico (1998). We reclassified the alien taxa according to the national standardisation system (Galasso et al. 2018a), based on the definitions provided by Richardson et al. (2000) and Pyšek et al. (2004), but supplemented by more detailed subcategories:

C cryptogenic species;

CAS occurring as a casual alien outside human-dominated systems;

CAS# occurring as a casual alien in human-dominated systems, but without direct intervention by humans and not close to parent plant;

CAS? occurring as casual alien, but still with some uncertainties for a definitive classification;

DD data deficient (unknown regional distribution or unknown alien status);

NAT occurring as a naturalized alien outside human-dominated systems;

NAT# occurring as a naturalized alien in human-dominated systems, without direct intervention by humans and not close to parent plant;

INV occurring as an invasive alien outside human-dominated systems;

ERA eradicated, eliminated during the last ten years;

+ new taxon for the Italian or the Ligurian flora;

+> new status (status change) of the taxon for the Italian or the Ligurian flora;

The nomenclature is according to Galasso et al. (2018a) and subsequent updating; taxa not included in the Portal to the Flora of Italy (2022) are named according to Plants of the World online (POWO 2021).

The Table 1 shows the 270 taxa analyzed and classified according to the status categories cited above. The list includes previous status at Capo Mortola (Campodonico et al. 1996), the status in Italy and in Liguria [Galasso et al. (2018a), updated according to Galasso et al. (2018a, b, 2019a, b, 2020a, b, 2021a, b), and according to Wikiplantbase#Liguria (Barberis et al. 2021)] and information on the trend.

We also provide some additional information and comments on a sample of 34 taxa for which we reconstructed the history of their presence in the study area.

Acacia provincialis A. Camus (Fabaceae)

+> (NAT) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'59.66"N, 7°33'10.40"E), semi-natural evergreen post-fire shrubland in wild area of Hanbury Botanic Garden, 77 m, 1 April 2021, M. Mariotti (HMGBH). – Status change from casual to naturalized alien for the flora of Italy (Liguria).

Acacia provincialis is an ornamental plant native to South Australia and Victoria, introduced in Tasmania; in Europe, it is recorded in France and Italy, where it has been introduced for ornamental and environmental purposes. The species was described by Camus in 1927 from cultivated material at Pampelonne, Ramatuelle, in the south of France (PACA), where the plant had been in cultivation since the 1870s and was popular in the cut flower trade as noted by Vilmorin (1893), Anonymous (1919), and Stapf and Ballard (1929). According to O’Leary (2007) in his review of Acacia retinodes Schltdl. and closely related species, A. uncifolia (J.M.Black) O’Leary and A. provincialis, since the description the species was confused with these related taxa. In Italy, all specimens previously attributed to A. retinodes must be referred to A. provincialis (Galasso et al. 2018a).

In autumn 1867, a few months after the establishment of the garden, plants labelled as A. retinodes were introduced to La Mortola from Charles Huber’s nursery-garden in Hyères. A. retinodes was recorded in all the catalogues of plants growing at La Mortola in Sir Thomas Hanbury’s Garden: Cronemayer (1889), Dinter (1897), Berger (1912), Ercoli and Lorenzi (1938), Campodonico et al. (1996); in the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as established (“Sptnzz.”). It has been established for several years, as shown by the various editions of the Index Seminum (various authors 1890–1939).

We carefully examined our specimens according O’Leary’s review, in particular many of the principal morphological features that allow to distinguish the three related species A. retinodes, A. uncifolia, and A. provincialis. Based on variable length of phyllodes, spacing of phyllodes along stem (uncrowded), long flowering time, number of flowers/head, and pod width we were able to identify the specimens as A. provincialis.

All specimens examined grow in the wild in a valley at La Mortola and have to be referred to A. provincialis; the species is widespread in a wild area of the Vallone della Sorba, in a post-fire Mediterranean shrubland community, locally with A. longifolia (Andrews) Willd., Eucalyptus sp. and Searsia pallens, as well as with native species of the maquis.

Acer oblongum Wall. ex DC. (Sapindaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'1.55"N, 7°33'20.48"E), exotic evergreen woodland, 50 m, 12 August 2021, E. Zappa, F. Pastor (HMGBH). – Casual alien species confirmed for the flora of the compendium.

Acer oblongum is an ornamental plant with native range from NE-Pakistan to C- and S-China and Indo-China, which is widely cultivated for gardens and bonsai. It was introduced in the GBH from seeds obtained from Villa Thuret (Antibes, France) – sent on 3^rd January 1870 – (Sowing & Planting 3, manuscript) – and it is recorded in the 1889, 1897, 1912, 1938, and 1996 Catalogues. Campodonico et al. (1996) in Hortus Mortolensis recorded the species as adventive. One old specimen grows in the central area of GBH, near the Dragon’s Fountain. Young plants are widespread in the surrounding neglected slopes, in semi-shade positions without any human cultivation; these plantlets are periodically removed to prevent further development. The species is recorded in various editions of the Index Seminum (since 1890 and following). Albericci et al. (2011) recorded a monumental tree of Acer oblongum in the Parco Gropallo (Genova, Italy), not found elsewhere in Italy with this size and age; they do not mention the possible naturalization of this species, but highlight its ability to adapt to the Mediterranean climate.

Alectryon tomentosus (F.Muell.) Radlk. (Sapindaceae)

+ (CAS) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'59.62"N, 7°33'22.62"E), exotic evergreen woodland, 40 m, 12 August 2021, E. Zappa (HMGBH); ibidem, Capo Mortola, Strada Romana (WGS84: 43°46'57.11"N, 7°33'21.91"E), wall above the ancient Roman Road, 22 m, 3 March 2022, E. Zappa (HMGBH). – Casual alien species new for the flora of Italy (Liguria).

Alectryon tomentosus is an ornamental plant, native to New South Wales and Queensland (Australia) that occurs naturally in rainforests; it commonly sprouts in Australian urban bushland, gardens, and roadsides. It is extremely hardy and can withstand dry periods and neglect (http://www.brisrain.org.au/01_cms/details.asp?ID=19). In the 19^th century, it was introduced as seed from the Royal Botanic Gardens Sidney (4^th July 1898) to La Mortola (Sowing & Planting 6, manuscript); it is recorded in 1912, 1938 and 1996 Hortus Mortolensis; in the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as adventive. The species is recorded in various editions of the Index Seminum (since 1912 and following). One old specimen grows in the “Australian Wood”; many young plants originating from the seeds produced by planta culta are widespread in the garden, in shady and semi-shade positions, especially in evergreen woodlands of the compendium; we observed a few individuals outside the botanical garden on the wall alongside the Strada Romana.

Asparagus virgatus Baker (Asparagaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'2.55"N, 7°33'21.27"E), exotic woodland, 63 m, 11 February 2021, E. Zappa (HMGBH). – Casual alien species confirmed for the flora of the compendium.

Asparagus virgatus is an ornamental plant, native to Angola, South Africa, Malawi, Mozambique, Namibia, Tanzania, Yemen, Zambia and Zimbabwe, introduced into Queensland (Australia), Réunion, Trinidad-Tobago. In Europe, it is reported only as cultivated for ornamental purposes. At La Mortola the species was first introduced in October 1901, by Carl Ludwig Sprenger (1846–1917), Naples (Sowing & Planting 7, manuscript), and then recorded in the 1912, 1938, and 1996 catalogues. In the last edition of Hortus Mortolensis (Campodonico et al. 1996), the species is reported as adventive. In GBH A. virgatus grows along marginal borders, in semi-shady and sheltered, undisturbed locations.

Brachychiton discolor F.Muell. (Malvaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'57.20"N, 7°33'21.54"E), exotic evergreen woodland, 25 m, 9 Sepember 2021, F. Pastor (HMGBH). – Casual alien species new for the flora of the compendium, where it was previously known only as cultivated (acclimated).

Brachychiton discolor is an ornamental tree native to New South Wales and Queensland, in dry rainforests, on well-drained slopes (Fern 2014). In Europe it was known only as ornamental since 2016, when it was recorded as casual alien in Sicilia (Raab-Straube and Raus 2016).

At la Mortola the species was first introduced in May 1893, as seeds from the Botanic Garden of Melbourne (Sowing & Planting 5, manuscript), and then recorded in 1912, 1938, and 1996 catalogues. It was described as a very handsome young tree that had not yet flowered (sub B. luridus C.Moore ex F.Muell.)(Berger 1912). In the last edition of Hortus Mortolensis (Campodonico et al. 1996), the species is reported as acclimated. One old specimen grows in the “Australian Wood”; some young plantlets originating from planta culta are widespread in the garden, in semi-shady neglected positions.

Bupleurum fruticosum L. (Apiaceae)

+> (C) LIG: Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'57"N, 7°33'16"E), evergreen woodland margins, 50 m, 12 August 2021, E. Zappa (HMGBH). – Species to be considered cryptogenic in Liguria.

Bupleurum fruticosum is a steno-Mediterranean species, typical of clayey slopes and stony garrigues (Pignatti et al. 2018), reported as native in Sicilia, Sardegna and Liguria (Isola Gallinara), not confirmed in Puglia (Bartolucci et al. 2018); the species is recorded as cryptogenic species in Toscana (Roma-Marzio and Peruzzi 2018) and as cryptogenic species extinct in Puglia (Roma-Marzio and Peruzzi 2018).

In Liguria, on the Isola Gallinara in front of Albenga (Savona), Béguinot (1907) observed the species only in one location and consider it among species introduced in cultivation; later Orsino (1975) recorded the species only in the highest area near the Villa and agrees with Beguinot in considering that this stand was first introduced as ornamental.

Caruel (1889) reports that B. fruticosum is often cultivated as ornamental in the gardens of the Italian peninsula and, in some cases, it has been erroneously considered wild, as in Nice by De Candolle according De Notaris (1844) [«Nicaeae, utique, sed in (hortis cultum)»].

The species occurs at Capo Mortola in evergreen wood areas. Date and origin of its introduction to the GBH is unknown: it was recorded in 1889, 1897, 1912, 1938, and 1996 catalogues. Seeds, collected from plants cited as indigenous, were available in exchange since the 1888 Index Seminum; the last edition of Hortus Mortolensis (Campodonico et al. 1996) considers the species established (“Sptnzz.”), i.e., naturalized. Furthermore, Berger (1905) did not include the species in the enumeration of the plants growing wild at La Mortola Florula Mortolensis.

As for Liguria, we suggest considering B. fruticosum a cryptogenic species for Liguria.

Chasmanthe bicolor (Gasp.) N.E.Br. (Iridaceae)

+> (NAT) LIG: Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'00.0"N, 7°33'11.5"E), exotic woodland, 70 m, 18 March 2021, E. Zappa (HMGBH); ibidem, Capo Mortola, rio Sorba Valley (WGS84: 43°46'54.26"N, 7°33'16.00"E), Pinus halepensis woodland, 25 m, 11 March 2022, F. Dente (HMGBH). – Status change from casual to naturalized alien for the flora of Liguria.

Chasmanthe bicolor is an ornamental bulbous plant native to Cape Province (South Africa) and introduced to California, Great Britain (Scilly Isles), Italy (https://www.catalogueoflife.org/data/taxon/TPZZ). According GBIF Secretariat (2021a), it is recorded as introduced also in France, Portugal, New Zealand and Australia. In Italy it is recorded as naturalized alien in Campania and Sicilia, casual alien in Calabria, Lazio, Liguria, Puglia and Toscana.

In GBH it was first grown from seeds received from Villa Thuret, Antibes in January 1870 (sub Antholyza; Berger 1912) (Sowing & Planting 3, manuscript). It is recorded in the 1889, 1897, 1912, 1938 and 1996 Catalogues; it has been established for several years, as Berger (1912) noted: “it is now almost a weed in the garden, but useful for covering bare places under trees with a pleasant green during winter and spring”. In the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as established (“Sptnzz.”) naturalized under the name of C. aethiopica (L.) N.E.Br. C. bicolor is widespread both in the garden, in woodland, in sunny, semi-shade and shady sheltered positions, neglected slopes and terraces and in evergreen woodland in the wild area of Vallone della Sorba.

Chasmanthium latifolium (Michx.) H.O.Yates (Poaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'1"N, 7°33'12"E), exotic woodland, 70 m, 12 August 2021, E. Zappa (HMGBH). – Casual alien species, new for the flora of the compendium, where it was previously recorded as cultivated.

Chasmanthium latifolium is an ornamental plant native to C-Canada, C- and E-USA to NE-Mexico, introduced to Europe in Austria and Belgium.

It was first introduced to GBH in 1994 (Hanbury Botanic Garden Accessions Register, manuscript); in the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as cultivated, but in recent years it became adventive. In the GBH, the species grows wild along the edge of flowerbeds and borders, in sheltered positions.

Chrysanthemoides monilifera (L.) Norl. subsp. monilifera (Asteraceae)

+> (NAT) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'59.66"N, 7°33'10.40"E), semi-natural evergreen post-fire shrubland in wild area of Hanbury Botanic Garden, 80 m, 18 March 2021, E. Zappa, L. Minuto (HMGBH). – Naturalized alien species confirmed for the flora of Italy (Liguria).

Chrysanthemoides monilifera (≡ Osteospermum moniliferum L.) is a semi-succulent shrub 1–3 m high, native to the sandy soils of southern and southeastern South Africa, where there are six subspecies (Scott and Brown 1992). Introduced to California, Australia (Queensland, South Australia, Victoria, Western Australia), Norfolk Island, New Zealand (North Island), France, Spain, and Italy, in Sicilia where it is no longer recorded. The species is included in the CABI (2021a) invasive species database. C. monilifera has been both deliberately and accidentally introduced into other countries. It is known to have been introduced as a garden ornamental. Subsp monilifera was introduced into Australia as an ornamental plant in the 1850s and was grown in gardens in Sydney, Melbourne and Adelaide (Parsons and Cuthbertson 1992). At La Mortola it was introduced in February 1869 from seeds given by Gustave Thuret of Antibes (Berger 1912). It is recorded in the 1889, 1897, 1912, 1938 and 1996 Hortus Mortolensis, where is reported as naturalized, and various editions of the Index Seminum since 1888. Gentile and Gentile (1994) observed the species in garrigues with Salvia rosmarinus Spenn. as differential species of groupings of the thermoxeric series.

Chrysojasminum humile (L.) Banfi (Oleaceae)

+> (NAT) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'57"N, 7°33'16"E), exotic woodland, 50 m, 15 July 2021, E. Zappa, M. Mariotti (HMGBH); ibidem, Capo Mortola, rio Sorba Valley (WGS84: 43°47'0.00"N, 7°33'12.10"E), mixed woodland of Pinus halepensis and exotic species, 50 m, 15 July 2021 (HMGBH). – Status change from casual to naturalized alien for the flora of Italy (Liguria).

Chrysojasminum humile is an ornamental plant native to Afghanistan, Assam, N-C-China, S-C-China, East and West Himalaya, Iran, Myanmar, Nepal, Pakistan, Tadzhikistan, Tibet, introduced to Greece, Italy, Sicilia, and Yugoslavia. In Europe, it is cultivated as ornamental and is recorded as casual alien in Italy (Galasso et al. 2018a). In GBH it is widespread in the garden, and in the wild area in rio Sorba valley.

We do not know the date and origin of its introduction to the GBH: it was recorded in the 1889, 1897, 1912, 1938 and 1996 catalogues. Seeds were available in exchange since the 1891 Index Seminum. In the last edition (Campodonico et al. 1996) the species is reported as cultivated; then it became naturalized as now it is widespread in neglected sites of the compendium, mainly in an evergreen woodland in the wild area of Vallone della Sorba, where it is common in shady locations.

Clematis armandii Franch. (Ranunculaceae)

+ (CAS) LIG: Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'59.52"N, 7°33'13.72"E), exotic woodland, 52 m, 18 March 2021, E. Zappa, F. Pastor (HMGBH). – Casual alien species new for the flora of Liguria.

Clematis armandii is an ornamental plant native to N-C-China, S-C-China, SE-China, Myanmar, Tibet, Vietnam, occurring in forests, forest margins, slopes, shrubs, along streams. In Europe it is known only as cultivated. It is among the plants collected by Ernest Henry Wilson (1876–1930) for James Herbert Veitch (1868–1907) in his first expedition (1899–1902) to China (Wilson 1905) and introduced to cultivation by James Veitch & Sons Nurseries. In this nursery, plants raised from seeds, sent by Wilson in 1900, flourished for the first time in spring 1905 as reported in a note on Gardeners’ Chronicle (Anonymous 1905). In his note “Recently introduced trees, shrubs & c. from Central China”, Veitch (1903) assumed C. armandii as “the best of the several species of Clematis introduced by Wilson in his recent trip”.

At la Mortola, a plant or cuttings of C. meyeniana Walp., later identified by Alwin Berger as C. armandii (Mottet 1921), was first introduced in 1904, October 25^th (Sowing & Planting 8, manuscript) from the Royal Botanic Gardens, Kew. The species is recorded in 1912, 1938, and 1996 editions of Hortus Mortolensis. In the 1938 catalogue, the species is reported to grow from seeds collected by Wilson in China. Seeds were available in exchange since the 1917 Index Seminum. In the last edition of the catalogue (Campodonico et al. 1996), the species is reported as acclimated; then it became established as now it is widespread in an evergreen woodland in the wild area in Vallone della Sorba, where it is common in shady neglected sites.

Enchylaena tomentosa R.Br. (Amaranthaceae)

+> (NAT) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'53.89"N, 7°33'28.46"E), sunny and dry slopes on poor soil and stones, cliff, rocks, 10 m, 12 August 2021, E. Zappa (HMGBH). – Status change from casual to naturalized alien for the flora of Italy (Liguria).

Enchylaena tomentosa is a small shrub native to Australia and introduced into New Caledonia and Palestine. In Italy, it was recorded by Alberti (2013) as casual alien species here, on the cliff rocks of Capo Mortola. The species is widespread on the Cape, in marginal sunny rock sites and slopes.

It was first introduced to GBH in April 1903, from seeds sent by Villa Thuret (Sowing & Planting 8, manuscript); it is recorded in 1912, 1938 and 1996 editions of Hortus Mortolensis; in the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as established (“Sptnzz.”) naturalized.

Ephedra altissima Desf. (Ephedraceae)

+ (NAT) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'2.29"N, 7°33'20.24"E), woodland margins, walls, terraces in olive groves, 65 m, 2 February 2021, F. Pastor (HMGBH); ibidem, Capo Mortola, Discesa del Marinaio (WGS84: 43°47'2.94"N, 7°33'21.89"E), Mediterranean shrubland, neglected olive trees, 75 m, 11 March 2022, F. Dente (HMGBH). – Naturalized alien species new for the flora of Italy (Liguria).

Ephedra altissima is an ornamental and medicinal climbing plant, native to Algeria, Canary Islands (Tenerife), Chad, Libya, Mauritania, Morocco, Tunisia, and western Sahara. In Europe it is known only as cultivated. It was first introduced to GBH before 1870 from seeds sent by Daniel Hanbury to La Mortola (letter dated 23^rd March 1870 in Winter manuscript). It is recorded in the 1889, 1897, 1912, 1938, and 1996 catalogues; it is also recorded in various editions of the Index Seminum (1890 onwards). In the last edition of Hortus Mortolensis (Campodonico et al. 1996), the species is reported as established (“Sptnzz.”), apparently naturalized. E. altissima is widespread inside and outside the compendium, on trees and walls, in sunny and sheltered neglected sites mainly in olive grove terraces; both female and male specimens are present, probably scattered by birds. We observed the species also on olive trees in sunny sites outside the Gardens.

Ferula communis L. subsp. communis (Apiaceae)

+> (C) LIG: observed at Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'0.30"N, 7°33'24.08"E), garrigues and arid slopes in wild areas of Hanbury Botanic Garden, widespread in the garden in sunny sites, 80 m, 2021. – Status change from native to cryptogenic for the flora of Liguria.

According to Caruel (1889), in Liguria the species occurs along the sea coast on the island of Bergeggi near Noli (datum from Giuseppe De Notaris), and on the Isola Gallinara near Albenga (datum from Antonio Bertoloni! and Giuseppe De Notaris), and in the region of Nice (France) (datum from Carlo Allioni). De Notaris (1844) reported Prof. Agostino Sassi’s citation in Gallinara island and Giuseppe Berti in Bergeggi island near Noli; Ottone Penzig (handwritten notes on a copy of the volume of De Notaris (1844) kept in Genova) added Bicknell’s record in Capo Mele.

At La Mortola, the species was introduced in 1868 by Daniel Hanbury on May 20^th and sown near the sea and in the garden (Berger 1912). It was recorded in the 1889, 1897, 1912, 1938 and 1996 catalogues and various editions of the Index Seminum since 1888. Campodonico et al. (1996) in the last edition of Hortus Mortolensis classify the species as established (“Sptnzz.”) naturalized. Marinella Zepigi uploaded on the “Acta Plantarum” portal a photo of the plant taken in Grimaldi (west of Capo Mortola) in 2008. The presence of this species, of ancient medicinal use, in the Bergeggi and Gallinara islands, once monastic settlements, lead us to assume its possible introduction by humans in these sites, as certainly occurred at Capo Mortola. This assumption is not yet documented by solid evidence and we suggest considering the species as cryptogenic for the flora of Liguria.

Jaborosa integrifolia Lam. (Solanaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'54.57"N, 7°33'22.45"E), grassy places in exotic woodland, 26 m, 11 November 2021, E. Zappa (HMGBH). – Casual alien species confirmed for the flora of the compendium.

Jaborosa integrifolia is an ornamental plant whose native range is from Brazil to N-Argentina and introduced into Alabama (USA). In Europe, it is recorded as casual alien species in Sardegna (Podda et al. 2012). At La Mortola, the species was first introduced before 1872 (Winter, manuscript); it is recorded in the 1938 and 1996 catalogues. In the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as adventive. In the compendium, the species is widespread in grassy sites and alongside paths.

Jasminum mesnyi Hance (Oleaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'0.39"N, 7°33'16.64"E), exotic woodland, 63 m, 23 April 2021, F. Pastor (HMGBH). – Casual alien species, new for the flora of the compendium, where it was previously known only as cultivated (acclimated).

Jasminum mesnyi is an ornamental plant native to S-C-China and Vietnam, introduced into Alabama and Florida (USA), NE-Argentina, Honduras, India, SE-Mexico, Pakistan, and western Himalaya. The species is recorded as invasive in USA, Australia, South Africa, Libya, and Iraq (GBIF Secretariat 2021b); in Italy it is recorded as casual and naturalized alien species (Galasso et al. 2018a).

J. mesnyi (sub J. primulinum Hemsl.) is among the plants collected by Wilson during his first trip in China in 1899–1902. In December 1903, three plants were introduced to La Mortola by Miss Ellen Willmott (Sowing & Planting 8, manuscript). The species is recorded in the 1912, 1938 and 1996 catalogues. In the last edition of Hortus Mortolensis (Campodonico et al. 1996), the species is reported as acclimated. In the compendium, we observed J. mesnyi growing in mixed borders and in shady and sheltered positions without direct human influence.

Koelreuteria bipinnata Franch. (Sapindaceae)

+ (CAS) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'56.86"N, 7°33'21.23"E), exotic woodland, 20 m, 12 August 2021, E. Zappa (HMGBH); ibidem, Capo Mortola, Strada Romana (WGS84: 43°46'56.6"N, 7°33'20.4"E), 20 m, 3 March 2022, E. Zappa (HMGBH); ibidem, Capo Mortola, rio Sorba Valley (WGS84: 43°47'0.27"N, 7°33'14.21"E), evergreen woodland, 60 m, 11 March 2022, F. Dente (HMGBH). – Casual alien species new for the flora of Italy (Liguria).

Koelreuteria bipinnata is an ornamental plant, native to S-China, occurring in sparse forests and slopes at 400–2,500 m a.s.l. (Xia and Gadek 2007), and introduced to the USA (California, Alabama and Arkansas) (Serviss et al. 2006; International Dendrology Society 2021) It is among the plants collected by Wilson during the Veicht expedition in 1900 (Rehder and Wilson 1914). Seeds of K. bipinnata were introduced to La Mortola in May 1893, sent by Henry Correvon of Geneva (Switzerland) (Sowing & Planting 5, manuscript).

The species is recorded in 1912, 1938 and 1996 editions of Hortus Mortolensis. Seeds were available in exchange starting from the 1911 Index Seminum; in the last catalogue (Campodonico et al. 1996), the species is reported as adventive. Many plantlets originating from the old specimen are widespread in the compendium, in shady positions, mainly in the lower garden, known as the Piana. We observed two mature individuals growing wild, one alongside the Strada Romana and the other in Vallone della Sorba, near the stream banks.

Lavandula dentata L. (Lamiaceae)

+ (CAS) LIG: Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'58.30"N, 7°33'18.82"E), sunny sheltered positions, walls, 56 m, 2 February 2021, F. Pastor (HMGBH); ibidem, La Mortola, ex strada SS1 (WGS84: 43°47'05.3"N, 7°33'15.8"E), wall, 105 m, 3 March 2022, F. Pastor (HMGBH). – Casual alien species new for the flora of Liguria.

Lavandula dentata is an ornamental shrub native to Algeria, Baleares, Eritrea, Ethiopia, Morocco, Palestine, Saudi Arabia, Spain, and Yemen, naturalized elsewhere around the Mediterranean (Greece, Italy, Tunisia) as well as in Bulgaria, Canary Islands, Cape Verde, Madeira, western Australia, New Zealand, and California.

The date and origin of its introduction to the GBH remains obscure; surely it happened before 1889, as the species is reported in the 1889, 1897, 1912, 1938 and 1996 catalogues. It is also recorded in the various editions of the Index Seminum (since 1909). In the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as adventive. L. dentata is widespread in the garden and outside in the village of La Mortola, on rocks, and walls, in sunny and sheltered positions.

Nandina domestica Thunb. (Berberidaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'1.06"N, 7°33'16.29"E), mixed borders, 66 m, 12 August 2021, E. Zappa (HMGBH). – Casual alien species, new for the flora of the compendium, where it was previously known only as cultivated (acclimated).

Nandina domestica is an ornamental plant native to N-C-China, S-C-China, SE-China, and Japan; introduced into S-USA, Assam, Korea, New South Wales (Australia), and Italy. We do not know date and origin of the species’ introduction to the GBH; it is surely before 1889, as the species is reported in the 1889, 1897, 1912, 1938 and 1996 catalogues. Seeds are available in various editions of the Index Seminum (since 1890 and following). In the last edition of Hortus Mortolensis (Campodonico et al. 1996) the species is reported as acclimated. Now it grows in mixed borders, in semi-shady sites, probably scattered by birds; we observed one individual under a cypress tree.

Parrotia persica (DC.) C.A.Mey. (Hamamelidaceae)

+ (CAS) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'0.00"N, 7°33'12.10"E), exotic woodland in wild area of Hanbury Botanic Garden, 60 m, 1 April 2021, E. Zappa, M. Mariottti (HMGBH). – Casual alien species new for the flora of Italy (Liguria).

Parrotia persica is an ornamental tree native to Iran, and Transcaucasia and introduced into Great Britain and Uzbekistan. It is not recorded in the updated checklist of the vascular flora alien to Italy (Galasso et al. 2018a). We do not know date and origin of the introduction to GBH, but it was recorded in the 1889, 1897, 1912, 1938 and 1996 catalogues. The last edition of Hortus Mortolensis (Campodonico et al. 1996) reports the species as acclimated.

At La Mortola, two plants of different age grow in an evergreen woodland with Pinus halepensis Mill. subsp. halepensis in Vallone della Sorba in the wild area of the compendium.

Passiflora morifolia Mast. (Passifloraceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'3.21"N, 7°33'15.56"E), borders in exotic woodland, 83 m, 21 September 2021, F. Pastor (FI, HMGBH). – Casual alien species new for the flora of the compendium.

Passiflora morifolia is an ornamental plant with a native range from Mexico (Guerrero, Chiapas) to S-tropical America, introduced into Canary Islands, S-C-China, Palestine, and Zimbabwe. It has been recently introduced into Europe, mainly for ornamental purposes. In Italy, it is recorded as naturalized in Sardegna (Galasso et al. 2020a).

At La Mortola, P. morifolia was introduced in 1999 coming from the Botanic Gardens of Rotterdam as seeds (sub P. brionioides Kunth, Hanbury Botanic Garden Accessions Register, manuscript); in the same year, two plants were introduced from Giardino Boccanegra (Ventimiglia, Italy). In recent years, the species has become adventive and, from the cultivated areas, has spread into the compendium, maybe scattered by birds, and grows in marginal sites, on walls, and fallow locations.

Pittosporum venulosum F.Muell. (Pittosporaceae)

+ (CAS) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'0.0"N, 7°33'11.5"E), exotic woodland in wild area of Hanbury Botanic Garden, 75 m, 1 April 2021, E. Zappa (HMGBH). – Casual alien species new for the flora of Italy (Liguria).

Pittosporum venulosum (= P. procerum Naudin) is an ornamental tree native to Australia (East Queensland). The plants of Capo Mortola are certainly derived from the typical material of Pittosporum procerum. This name is reported by WFO (2021) database as ambiguous, while POWO (2021) considers it as a synonym of P. venulosum.

In 1899 Charles Naudin described P. procerum and introduced it to cultivation in Villa Thuret, Antibes (France); in 1903 and 1904 seeds were introduced from Villa Thuret to La Mortola (Sowing & Planting 8, manuscript). Seeds became available for exchange since 1912 (Index Seminum 1912). The species is recorded in the 1912, 1937 and 1996 catalogues; the last edition of Hortus Mortolensis (Campodonico et al. 1996) reports the species as acclimated. We observed some plants, in juvenile and mature phases, in Vallone della Sorba, the wild area of the compendium, in a mixed evergreen woodland with Pinus halepensis subsp. halepensis.

Quercus coccifera L. (Fagaceae)

+ (C) LIG: Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'59.4"N, 7°33'24.3"E), evergreen woodland margins, 65 m, 18 March 2021, E. Zappa, L. Minuto (HMGBH). – Cryptogenic species confirmed for the flora of Liguria.

Quercus coccifera is a western Mediterranean species. Pignatti et al. (2017) according Brullo and Spampinato (2004), reported the species widespread mainly in Languedoc, Catalonia and Tunisia, in Italy only in western Liguria (0–200 m); while Bartolucci et al. (2018) recorded the species occurring in Puglia, Basilicata, Sicilia, Sardegna and doubtfully in Liguria.

Penzig (handwritten notes on a copy of the volume of De Notaris (1844) kept in Genova) reported: “Nym. Prosp. Lig.”, and Ardoino’s, Allioni’s, Reichenbach’s, Burnat’s recordings of the species as very rare occurring around Nice. Parlatore (1868) reported Allioni’s citation: around Nice, where it is rare. The Portal to the Flora of Italy (2022) reports this species in Liguria only with doubtful records.

The species occurs at Capo Mortola in evergreen wood and in post-fire Mediterranean shrubland community. We do not know date and origin of the introduction to the GBH: it was recorded in the 1889, 1897, 1912, 1938 and 1996 catalogues. Seeds were available in exchange since the1896 Index Seminum; the last edition of Hortus Mortolensis (Campodonico et al. 1996) reports the species as acclimated. It was not included in Florula Mortolensis (Berger 1905), the catalogue of all plants growing wild at La Mortola.

For Liguria, we suggest considering Q. coccifera as a cryptogenic species.

Roldana petasitis (Sims) H.Rob. & Brettell (Asteraceae)

(NAT) LIG: Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'2.01"N, 7°33'11.76"E), evergreen woodland margins, 60 m, 15 June 2021, F. Pastor (HMGBH). – Naturalized alien species: further record for Liguria.

Roldana petasitis is an ornamental plant native to the Gulf of Mexico, and NE-Mexico and introduced to Azores, Canary Islands, France, Italy, Java, Madeira, Mauritius, Australia (New South Wales, Norfolk Island, Victoria), Réunion, and Spain. In Italy, it is recorded as casual alien species (Galasso et al. 2018a; Galasso et al. 2019b) in Basilicata, Lazio, Puglia and Sicilia, naturalized in Liguria (Longo 2012).

The species was reported in the 1897, 1912, 1938 and 1996 catalogues. In 1996, the species is reported in Hortus Mortolensis as acclimated (Campodonico et al. 1996); it became established in recent years. In the compendium R. petasitis grows along woodland edges on stream banks in Vallone della Sorba, without direct human intervention.

Romneya coulteri Harv. (Papaveraceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'59.98"N, 7°33'17.95"E), exotic woodland, 58 m, 12 August 2021, E. Zappa (HMGBH). – Casual alien species, new for the flora of the compendium, where it was previously known only as cultivated (acclimated).

Romneya coulteri is an ornamental plant native from S-California to Mexico (N-Baja California), introduced into New South Wales, S-Australia, and W-Australia. In Europe, it is known only as cultivated.

R. coulteri was first introduced to GBH before 1897, as it is recorded in the 1897, 1912, 1938, and 1996 catalogues. In April 1899, a plant was introduced by Miss Ellen Willmott and in May 1901, seeds from the Southern California Acclimatization Association were delivered to La Mortola (Sowing & Planting 8, manuscript). In the last edition of Hortus Mortolensis (Campodonico et al. 1996), the species is reported as acclimated. In the compendium, some individuals of the species grow wild in sunny and sheltered positions lacking direct human interventions.

Rosa banksiae W.T.Aiton var. normalis Regel (Rosaceae)

(+) (NAT) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'3.14"N, 7°33'9.08"E), evergreen woodland, 80 m, 18 March 2021, E. Zappa (HMGBH). – Status change from casual to naturalized alien for the flora of Italy (Liguria); naturalized alien variety new for the flora of Italy (Liguria).

Rosa banksiae W.T.Aiton [var. normalis Regel] f. lutescens Voss (Rosaceae)

(+) (CAS) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'3.47"N, 7°33'16.32"E), evergreen woodland margins, 85 m, 1 April 2021, F. Pastor (HMGBH); ibidem, Capo Mortola, rio Sorba Valley (WGS84: 43°47'4.35"N, 7°33'8.50"E), evergreen woodland, 100 m, 1 April 2021, F. Pastor (HMGBH). – Casual alien form new for the flora of Italy (Liguria).

Rosa banksiae is an ornamental plant, native to western mountainous half of China: Yunnan, Shensi, Kansu, Hupeh and Szechwan where it was found wild by Europeans collecting in China. The species ([var. banksiae] f. banksiae, the double-white flowered variety) was first introduced to England in 1807 by William Kerr. The yellow double flowered form ([var. banksiae] f. lutea (Lindl.) Rehder) was brought in later by John Damper Parks in 1824; under cultivation a single state of the last has been obtained, which is described and figurate in plate 7171 of Botanical Magazine. In the wild state, yellow flowers do not seem ever to occur (Henry 1902).

Rosa banksiae var. normalis (with single flower) is a rampant evergreen climber reaching up to 15 m or more, native to central and western China from Hubei and Gansu to Yunnan, usually at low altitudes but recorded up to 1,800 m a.s.l. It grows in valleys, by streams and rocky places, flowering from April to June. It was first introduced to Europe by Robert Drummond in 1796, and planted at Megginch Castle on Tayside, where it seldom flowered and remained unrecognized until cuttings were taken to Nice in 1905, where they flowered and were identified (Phillips and Rix 1988).

R. banksiae var. normalis is recorded in the 1938 and 1996 editions of Hortus Mortolensis, but it was introduced around 1912, maybe as part of the collection received from Mr. Wilson, as reported by Berger (1912). “Wilson N° 619, L.M., 2 July 1913” is written on the label of a specimen in our herbarium (HMGBH); the seeds were available in the 1913 Index Seminum.

According the forum actaplantarum.org, Franco Fenaroli recorded R. banksiae photographed in 2008 outside the boundary wall of a villa at Gardone Riviera (Province of Brescia) and said he had never seen it naturalized; Daniela Longo cited R. banksiae photographed in 2013 at Capo Mortola. Both do not provide any information on infraspecific rank. Based on the images available online, the plants photographed seem to refer to two different varieties: var. normalis (single flower) in Capo Mortola and var. banksiae (double or full flowered) in Gardone Riviera.

Campodonico et al. (1996) reported R. banksiae var. normalis as established (“Sptnzz.”), as it is widespread in the compendium, mainly in the wild area in Vallone della Sorba, where is common in shady situations within the woodland, climbing on trees up to 10 m or more.

The yellow single-flowered form (f. lutescens) is of unknown origin and its date of introduction is not recorded. Phillips and Rix (1988) noted both the double and single forms apparently growing on the same plant in an old garden on the Riviera and explained that the single yellow may appear as a reverse sport on the commoner double. Nothing is known as to its introduction at La Mortola, but it was already cultivated before December 1870, as noted by J.V.V. (1877), by Thomas Hanbury (1878) on Gardeners’ Chronicle and by Winter (manuscript, 6^th December 1870, letter to Daniel Hanbury). In the same years, as reported by Emanuele Orazio Fenzi (1878) on Gardener’s Chronicle, Eugenio Baroni, chief gardener at Florence Botanic Garden, obtained yellow single flowers plant. Woodall (1878), in another note on Gardeners’ Chronicle reported about single yellow form specimen in Nice and other locations in French Riviera observed in the spring of 1873 and in flower in 1876.

Berger (1912) noted that single yellow flower form was the most abundant rose in the garden of Sir T. Hanbury. R. banksiae f. lutescens is recorded in 1889, 1897, 1912, 1938 and 1996 catalogues; it has been established for several years, as shown by the various editions of the Index seminum (since 1890 and following). Campodonico et al. (1996) reported f. lutescens as adventive; it is widespread in the garden and in semi-natural areas of Vallone della Sorba.

Rosa brunonii Lindl. (Rosaceae)

+ (NAT) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'3.76"N, 7°33'8.61"E), evergreen woodland, 84 m, 5 April 2021, F. Pastor (HMGBH). – Naturalized alien species new for the flora of Italy (Liguria).

Rosa brunonii is an ornamental plant native to Afghanistan, Assam, S-C-China, East and West Himalaya, Myanmar, Nepal, Pakistan, and Tibet, introduced to Europe in 1823 as R. napaulensis Andrews.

We do not know date and origin of the introduction to the GBH: the species is recorded in the 1938 and 1996 editions of Hortus Mortolensis; seeds were available in exchange since the 1922 Index Seminum. In the last edition (Campodonico et al. 1996), the species is reported as established (“Sptnzz.”), as it is widespread in the compendium, mainly in the wild area of Vallone della Sorba, where is common in shady situations, climbing on trees up to 15 m or more.

R. brunonii ‘La Mortola’ is an ornamental cultivar originated in the GBH by a sport of R. brunonii, first brought to England by Edward Bunyard in the 1930s (Quest-Ritson 2013) and introduced into commerce by Sunningdale Nursery in 1954 (HelpMeFind 2021).

Searsia pallens (Eckl. & Zeyh.) Moffett (Anacardiaceae)

+ (CAS) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'59.66"N, 7°33'10.40"E), semi-natural evergreen post-fire shrubland in wild area of Hanbury Botanic Garden, 77 m, 25 February 2021, E. Zappa (HMGBH). – Casual alien species new for the flora of Italy (Liguria).

Searsia pallens is an ornamental plant native to Botswana, South Africa, and Lesotho. In Europe it is only known as cultivated. The species was introduced to La Mortola in June 1872, as Rhus excisa Thunb. var. pallens (Eckl. & Zeyh.) Sond. by seeds received from prof. Peter Mac Owan (Berger 1912), director of the Cape Town Botanical Garden.

The species was reported in the 1889, 1897, 1912, 1938, and 1996 catalogues. Seeds became available for exchanges since 1909. Inside the boundary of the compendium, in the wild area of Vallone della Sorba, individuals of S. pallens occur in a post-fire Mediterranean shrubland community.

Senecio linifolius L. (Asteraceae)

+ (CAS) ITALIA (LIG): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'3"N, 7°33'21"E), margins of sunny and dry slopes in Hanbury Botanic Garden, 70 m, 1 April 2021, E. Zappa (HMGBH); ibidem, Capo Mortola, Discesa del Marinaio (WGS84: 43°47'2.94"N, 7°33'21.89"E), mediterranean shrubland, 75 m, 11 March 2022, F. Dente (HMGBH). – Casual alien species new for the flora of Italy (Liguria).

Senecio linifolius is a small half succulent shrub native to the eastern Cape Province and Lesotho, previously known in literature with the illegitimate name Senecio longifolius L.

Senecio linifolius L. (Linnaeus 1759) was based on a South African collection in the herbarium of Johannes Burman (Wijnands 1983). Linnaeus (1763) later published the replacement name S. longifolius L. for the species to avoid homonymy with his new combination S. linifolius (L.) L. (Linnaeus 1763) for a Mediterranean species based on Solidago linifolia L. (Linnaeus 1753). The name S. linifolius L. [1759] is therefore correctly applied to the South African species (Calvo et al. 2013).

The species was introduced as S. longifolius L. to La Mortola by seeds received in June 1872, probably from Prof. Peter MacOwan (Berger 1912); it soon became sub-spontaneous in the garden according to Berger. It was recorded in the 1889, 1897, 1912, 1938, and 1996 catalogues; seeds became available for exchanges since the 1888 Index Seminum. In the last edition of Hortus Mortolensis, Campodonico et al. (1996) consider the species established (“Sptnzz.”). We observed some plants outside the Garden on sunny and dry slope.

Setaria palmifolia (J.Koenig) Stapf (Poaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'56.92"N, 7°33'20.16"E), exotic woodland garden, 26 m, 4 February 2021, F. Pastor (HMGBH). – Casual alien species, new for the flora of the compendium, where it was previously known only as assisted.

Setaria palmifolia is an ornamental plant native from tropical and subtropical Asia to E-Australia, introduced to W- and S-Australia, New Zealand, Pacific Islands and S- and C-America, with sporadic records in C-Africa (GBIF Secretariat 2021c), where it has naturalized and become invasive in many new territories, especially on the Pacific islands, including Hawaii (CABI 2021b). In Europe, it is known only as cultivated. The species is recorded in the EPPO database.

We do not know date and origin of the introduction to the GBH, but it was surely before 1889, as the species was reported in the 1889, 1897, 1912, 1938, and 1996 catalogues. In the last edition of Hortus Mortolensis (Campodonico et al. 1996), the species is reported as assisted, but in recent years it became established. At La Mortola, S. palmifolia occurs as a weed in flowerbeds and borders, especially, but not limited to, those that are regularly watered, in sheltered positions.

Trachelospermum jasminoides (Lindl.) Lem. (Apocynaceae)

(CAS#): Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°47'2.29"N, 7°33'20.24"E), sunny places on terraces in olive groves, 62 m, 15 September 2021, F. Pastor (HMGBH). – Casual alien species, new for the flora of the compendium, where it was previously known as acclimated.

Trachelospermum jasminoides is an ornamental plant native to N-C-China, S-C-China, SE-China, Hainan, Japan, Korea, Taiwan, Tibet, and Vietnam; it has been introduced and can be found naturalized in Pakistan, India, the USA, Mexico, C-America, and the Bahamas (Rojas-Sandoval 2017). The species is a popular garden plant in Australia, New Zealand, and Europe. In GBH it was first introduced before 1891, as it is reported in the Index Seminum since 1891 and is recorded in the 1897, 1912, 1938, and 1996 catalogues. In the last edition of Hortus Mortolensis (Campodonico et al. 1996), the species is reported as acclimated. The species grows along marginal borders, but not limited to, those that are regularly watered, in semi-shady and sheltered positions. Some young individuals grow wild on terraces of olive orchards. The cultivar ‘Wilsonii’, reported by Campodonico et al (1996) as adventive, is currently observed only as cultivated.

Vachellia karroo (Hayne) Banfi & Galasso (Fabaceae)

+ (CAS) LIG: Ventimiglia (Imperia), Capo Mortola, in the Area Protetta Regionale Giardini Botanici Hanbury (WGS84: 43°46'58.70"N, 7°33'23.42"E), sunny and dry places, 12 m, 21 September 2021, F. Pastor (HMGBH). – Casual alien species new for flora of Liguria.

Vachellia karroo is an ornamental plant native to South Africa, Angola, Botswana, Malawi, Mozambique, Namibia, Zambia, and Zimbabwe; introduced into the Mediterranean area, Portugal, NE-Argentina, Bolivia, C-Chile, India, Iraq, Mauritius, Myanmar, Paraguay, and Australia (Queensland and Western Australia), where the species is known to behave invasively. In Europe, it is cultivated as ornamental and is recorded as casual and naturalized alien in Italy (Galasso et al. 2018a), but was recently recorded as invasive in Sardegna (Galasso et al. 2021a). In the GBH it was introduced in autumn 1867, with other acacias brought from Charles Huber’s nursery-garden in Hyères (Plants sent by Hubers to the Palazzo Orengo. Dec. 1867. Manuscript, Hanbury Archives); the species was reported in the 1889, 1897, 1912, 1938, and 1996 catalogues. Seeds became available for exchanges since 1890. Campodonico et al. (1996) reported the taxa as established (“Sptnzz.”). In the compendium, V. karroo is widespread in sunny and semi-shady dry locations, in marginal shrubland.

The 1996 catalogue of the compendium listed 2,672 taxa; in the last thirty years this number varied between 2,500 and 3,000. The investigations carried out on 270 taxa recorded at the Area Protetta dei Giardini Botanici Hanbury (Capo Mortola, Ventimiglia, Italy) allowed us to record the current presence of 198 taxa of exotic origin, excluding cultivated or assisted taxa: 15 invasive, 65 naturalized, 76 casual, 37 occurring as casual in human-dominated systems, but without direct intervention by humans and not close to parent plant, 15 occurring as casual alien, but still with some uncertainties for a definitive classification. In addition to these, 3 species have been classified as cryptogenic and 1 as eradicated (extinct). In 1996, 229 species were reported: 87 naturalized and 142 adventitious (casual). 40 taxa show an increasing trend and 41 a decreasing or disappearing trend; 22 taxa reported as adventitious and 2 as naturalized in 1996 are no longer present or are present only with cultivated plants. On the other hand, numerous species, which in 1996 were classified as acclimated, have now become casual or naturalized. Regressive phenomena are also observed, which may depend, at least in part, on differences in the method of assessing status. The origin of the current alien flora of Capo Mortola is shown in Table 2: American taxa prevail with 21.8%; the Mediterranean and Mediterranean-Atlantic (including Macaronesian) ones are slightly less (20.7%). These are followed by Asian (15.7%), African (15.4% – mainly from South Africa), Eurasian (7.6%), and Australian/Australasian (6.6%) taxa.

Although an exact comparison with the national list (Galasso et al, 2018a) is not possible, because it does not consider taxa growing in botanic gardens, our study highlights 28 taxa that would be new to the Italian flora (25 casual and 3 naturalized) and 24 to the Ligurian flora (all casual) if we consider also the wild or neglected areas inside the botanical gardens. Many of these taxa will probably also be observed outside botanic gardens in the coming years. If we consider only the wild areas of Capo Mortola, 10 taxa are new to the Italian flora (7 casual and 3 naturalized) while 14 are new to the Ligurian flora only (all casual). In addition, 9 status changes are proposed on a national scale and 17 on a regional scale. Our study is the first in Italy to deal with the dynamics of invasion processes originating from botanic gardens. Over the past 25 years, 41 taxa that form this alien flora showed an increasing trend, while 41 taxa declined in the wild; 139 taxa showed no significant changes in their status. For 37 taxa, data are deficient, and an assessment of their status is now impossible. One species, Baccharis halimifolia L., was recently eradicated and appears to be extinct in nature. The local history of the presence of a sample group of 34 taxa (32 species), of which 11 are new to Italy or have a new status, was analyzed (Table 3): 7 of these taxa were certainly introduced in the first 10 years from the foundation of the gardens in 1867, 17 in the following years of the 19^th century, 8 in the first thirty years of the 20^th century and 2 in the last decade of the same century. Excluding the cryptogenic species, only 10 of the remaining taxa are also reported in the exotic flora of the neighboring French PACA region. These data are preliminary, and it would be useful to extend the historical analysis and the comparison with the situation of the nearby Côte d’Azur to the complete set of species reported in Table 1.

We also tried to clarify the status of species recorded as native in Liguria in recent times, but whose native character was already questioned by botanists of the past. Our study represents a starting point for an analysis extended to all taxa over a wider area, in a territory that is very sensitive to the impact of invasions of exotic species on natural biodiversity, and for a comparison with neighboring France. The data obtained, although preliminary, do not show a worsening of the invasion process. Indeed, a specific evaluation protocol aimed at preventing the potential risk of escape of exotic species from the Giardini Botanici Hanbury and invasion of the surrounding areas was adopted in the last decade.

We gratefully acknowledge the following colleagues: Fulvio Dente, Stefano Ferrari, Luigi Minuto, and Fabrizio Pastor. We also thank the reviewers of the manuscript for their valuable suggestions.