Three New Alien Taxa for Europe and a Chorological Update on the Alien Vascular Flora of Calabria (Southern Italy).

Knowledge on alien species is needed nowadays to protect natural habitats and prevent ecological damage. The presence of new alien plant species in Italy is increasing every day. Calabria, its southernmost region, is not yet well known with regard to this aspect. Thanks to fieldwork, sampling, and observing many exotic plants in Calabria, here, we report new data on 34 alien taxa. In particular, we found three new taxa for Europe (Cascabela thevetia, Ipomoea setosa subsp. pavonii, and Tecoma stans), three new for Italy (Brugmansia aurea, Narcissus 'Cotinga', and Narcissus 'Erlicheer'), one new one for the Italian Peninsula (Luffa aegyptiaca), and 21 new taxa for Calabria (Allium cepa, Asparagus setaceus, Bassia scoparia, Beta vulgaris subsp. vulgaris, Bidens formosa, Casuarina equisetifolia, Cedrus atlantica, Chlorophytum comosum, Cucurbita maxima subsp. maxima, Dolichandra unguis-cati, Fagopyrum esculentum, Freesia alba, Juglans regia, Kalanchoë delagoënsis, Passiflora caerulea, Portulaca grandiflora, Prunus armeniaca, Prunus dulcis, Solanum tuberosum, Tradescantia sillamontana, and Washingtonia filifera). Furthermore, we provide the first geolocalized record of Araujia sericifera, the confirmation of Oxalis stricta, and propose a change of status for four taxa (Cenchrus setaceus, Salpichroa origanifolia, Sesbania punicea, and Nothoscordum gracile) for Calabria. The updated knowledge on the presence of new alien species in Calabria, in Italy and in Europe could allow for the prevention of other new entries and to eliminate this potential ecological threat to natural habitats.

1. Introduction

The increase in alien plant invasion represents a very significant ecological problem for native flora [1]. This produces several impacts around the world such as the reduction of native and endemic species and habitats, but also damage to socio-economic and human health [2,3,4,5,6]. For example, R. pseudocacia L. has several effects on the endangered lichen species Lobaria pulmonaria (L.) Hoffm. (loss of diversity, among others) that are also due to climate change [7,8,9]. Thanks to a recent work, several invasive alien species were assessed in Italian regions [10]: in Toscana, Carpobrotus acinaciformis (L.) L. Bolus produces a reduction in native biodiversity and habitat degradation in the habitat of 1240, whereas in Lombardia, Lagarosiphon major (Ridl.) Moss produces primary production alteration and modification of natural benthic communities in the habitats of 3140 and 3150, respectively.

Although Calabria has been the object of interest by numerous scholars since 1800 [11,12,13,14,15], only in recent decades has there been a significant increase in botanical studies that have affected its territory in various investigation fields: such as floristic [16,17,18,19,20,21,22], phytosociological [23,24,25,26,27,28], ethnobotanical [29,30,31,32,33,34,35], and many others [36,37,38,39,40,41,42]. However, these works only in part provided data on the alien flora present in the Calabrian territory.

According to Bartolucci et al. [43], Calabrian vascular flora amounts to 2799 taxa including native, cryptogenic, and alien taxa. As for these latter, Galasso et al. [1] recorded, for this region, “only” 267 alien taxa; therefore, Calabria seems to be one of the Italian regions with the fewest exotic taxa in a spontaneous state! According to Musarella et al. [44], this is probably due to a lack of knowledge of vascular flora in the most anthropized areas. However, many contributions were later added to [1] and have increased the knowledge on the invasive alien flora in Calabria [44,45,46,47,48,49,50,51,52]. A recent work estimates that Calabrian alien vascular flora amounts to 336 taxa [53]. Subsequently, another eight taxa have been reported as new to Calabria by Galasso et al. [54].

This paper aims to document new records (collected specimens and observations) of alien plant taxa for Calabria (Figure 1). For each taxon, relevant information about the ecology and distribution and a careful assessment of the naturalization status is also provided.

Figure 1

Distribution of the 34 alien taxa recorded for the flora of Calabria (Southern Italy, Europe). Calabrian provinces: CS = Cosenza, CZ = Catanzaro, KR = Crotone, RC = Reggio Calabria, VV = Vibo Valentia.

2. Results

In this research work, we report 34 alien taxa recorded in several places of Calabria with different status of invasiveness (Figure 2; Table 1; Appendix A). Among these, three taxa are new for Europe (Cascabela thevetia, Ipomoea setosa subsp. pavonii, and Tecoma stans), three are new for Italy (Brugmansia aurea, Narcissus ‘Cotinga’, and Narcissus ‘Erlicheer’), one is new for the Italian Peninsula (Luffa aegyptiaca), and 21 are new for Calabria (Allium cepa, Asparagus setaceus, Bassia scoparia, Beta vulgaris subsp. vulgaris, Bidens formosa, Casuarina equisetifolia, Cedrus atlantica, Chlorophytum comosum, Cucurbita maxima subsp. maxima, Dolichandra unguis-cati, Fagopyrum esculentum, Freesia alba, Juglans regia, Kalanchoë delagoënsis, Passiflora caerulea, Portulaca grandiflora, Prunus armeniaca, Prunus dulcis, Solanum tuberosum, Tradescantia sillamontana, and Washingtonia filifera). Furthermore, we provide, for Calabria, the first geolocalized record of Araujia sericifera, the confirmation of Oxalis stricta, and propose a change of status for Cenchrus setaceus, Salpichroa origanifolia, and Sesbania punicea from naturalized to invasive, and for Nothoscordum gracile from casual to invasive. Some taxa were found in only one place, while others in several places, for a total of 118 records (Table S1).

Figure 2

Current status of invasiveness of the 34 alien taxa recorded for the flora of Calabria (Southern Italy, Europe).

Table 1

List of the 34 alien taxa recorded for the flora of Calabria (Southern Italy, Europe), with their eventual first record for Europe, first record for Italy, or confirmation for Calabria, and finally, the current status of invasiveness in the region and the previous one if changed.

ID	Taxon	First Record for Europe	First Record for Italy	First Record for Calabria	Confirmation for Calabria	Current Status	Previous Status
1	Allium cepa L.			X		C
2	Araujia sericifera Brot.			G		C
3	Asparagus setaceus (Kunth) Jessop			X		C
4	Bassia scoparia (L.) Voss			X		C
5	Beta vulgaris L. subsp. vulgaris			X		N
6	Bidens formosa (Bonato) Sch. Bip.			X		C
7	Brugmansia aurea Lagerh.		X			C
8	Cascabela thevetia (L.) Lippold	X				C
9	Casuarina equisetifolia L.			X		C
10	Cedrus atlantica (Endl.) G. Manetti ex Carrière			X		C
11	Cenchrus setaceus (Forssk.) Morrone					I	N
12	Chlorophytum comosum (Thunb.) Jacques			X		C
13	Cucurbita maxima Duchesne subsp. maxima			X		C
14	Dolichandra unguis-cati (L.) L.G. Lohmann			X		C
15	Fagopyrum esculentum Moench			X		C
16	Freesia alba (G.L. Mey.) Gumbl.			X		C
17	Ipomoea setosa Ker Gawl. subsp. pavonii (Hallier f.) J.R.I. Wood & Scotland	X				C
18	Juglans regia L.			X		C
19	Kalanchoë delagoënsis Eckl. & Zeyh.			X		C
20	Luffa aegyptiaca Mill.		IP	X		C
21	Narcissus ‘Cotinga’		X			N
22	Narcissus ‘Erlicheer’		X			C
23	Nothoscordum gracile (Aiton) Stearn					I	C
24	Oxalis stricta L.				X	C
25	Passiflora caerulea L.			X		C
26	Portulaca grandiflora Hook.			X		C
27	Prunus armeniaca L.			X		C
28	Prunus dulcis (Mill.) D.A. Webb			X		C
29	Salpichroa origanifolia (Lam.) Baill.					I	N
30	Sesbania punicea (Cav.) Benth.					I	N
31	Solanum tuberosum L.			X		C
32	Tecoma stans (L.) Juss. ex Kunth	X				C
33	Tradescantia sillamontana Matuda			X		C
34	Washingtonia filifera (Linden ex André) H. Wendl. ex de Bary			X		C

Notes: X = New or confirmed record; G = first Geolocalized record; IP = new record only for Italian Peninsula. Current and previous status of invasiveness: C = Casual; N = Naturalized; I = Invasive.

In particular, as below discussed and already confirmed by Spampinato et al. [50], Cenchrus setaceus, among others, showed a high degree of invasion in natural habitats. Other taxa have also been found in protected sites falling within the Natura 2000 network: Beta vulgaris subsp. vulgaris, Cedrus atlantica, Fagopyrum esculentum, Freesia alba, Juglans regia, and Nothoscordum gracile.

3. Discussion

The continuous and constant increase in a short time of new records of alien taxa in the Calabrian territory, and generally in Italy and Europe, represents a worrying threat for the autochthonous biodiversity and a clear sign of the ongoing climate change [55].

As shown in Figure 1, most of the new reports of alien taxa occurred within inhabited areas; these have a high risk of future invasion of natural habitats [56]. A total of 85% of recorded taxa is “casual”, 3% “naturalized”, and 12% is “invasive”. This last percentage of invasive taxa comes from a change of status that we propose in the present work, which means that several taxa continue to expand their range of distribution, representing a constant threat for native species and habitats.

Several records have been found along roadsides (Figure 3). Indeed, roadsides are places where alien taxa can establish [57,58] and are a considerable way to invade other areas [59]. Obviously, roads were also the places traveled by us during our research as it is more common to find new alien taxa along them. This does not mean that other habitats are not good places for alien taxa: in fact, numerous taxa have been encountered in other habitats but not considered here because they have already been reported previously for Calabria. In this study, we found that, out of 118 records, 60% were found along roadsides (Figure 3)! Only 8% were found in sidewalks and in temporary water bodies such as drainage channels and fiumare (typical rivers of southern Italy with torrential and irregular regime.), 7% in uncultivated fields, 5% in crop habitats, and 12% in other habitats (outcropping rocks, walls, shrublands and ruins). More details are reported in Table 2.

Figure 3

Habitats of the 34 alien taxa recorded for the flora of Calabria (Southern Italy, Europe).

Table 2

Detailed list of the 34 alien taxa recorded to Calabria (Southern Italy, Europe) including family, period of introduction, native range, life form, habitat, and number (No.) of records for each taxon.

ID	Taxon	Family	Period of Introduction	Native Range	Life Form	Habitat	No. of Records
1	Allium cepa L.	Amaryllidaceae	Archeophyte	Culton	G bulb	Crop	1
2	Araujia sericifera Brot.	Apocynaceae	Neophyte	Southern America	P lian	Roadside	2
3	Asparagus setaceus (Kunth) Jessop	Asparagaceae	Neophyte	Southern Africa	P lian	Uncultivated field	5
4	Bassia scoparia (L.) Voss	Chenopodiaceae	Neophyte	Central Asia	T scap	Roadside	1
5	Beta vulgaris L. subsp. vulgaris	Chenopodiaceae	Archeophyte	Culton	H scap	Crop/Uncultivated field/Roadside	7
6	Bidens formosa (Bonato) Sch. Bip.	Asteraceae	Neophyte	Northern and Central America	T scap	Roadside	2
7	Brugmansia aurea Lagerh.	Solanaceae	Neophyte	Ecuador	NP	Roadside	1
8	Cascabela thevetia (L.) Lippold	Apocynaceae	Neophyte	Central and Southern America	Ch frut	Temporary water body	2
9	Casuarina equisetifolia L.	Casuarinaceae	Neophyte	Australia	P scap	Wall	2
10	Cedrus atlantica (Endl.) G. Manetti ex Carrière	Pinaceae	Neophyte	Northern Africa	P scap	Shrubland	2
11	Cenchrus setaceus (Forssk.) Morrone	Poaceae	Neophyte	Northern and Eastern Africa and Arabian Peninsula	H caesp	Roadside	6
12	Chlorophytum comosum (Thunb.) Jacques	Asparagaceae	Neophyte	Southern Africa	H scap	Temporary water body	2
13	Cucurbita maxima Duchesne subsp. maxima	Cucurbitaceae	Neophyte	Culton	T scap	Temporary water body/Roadside	2
14	Dolichandra unguis-cati (L.) L.G. Lohmann	Bignoniaceae	Neophyte	Southern America	P lian	Temporary water body/Ruins	3
15	Fagopyrum esculentum Moench	Polygonaceae	Neophyte	Asia	T scap	Roadside	1
16	Freesia alba (G.L. Mey.) Gumbl.	Iridaceae	Neophyte	Southern Africa	G bulb	Roadside/Ruins/Wall	3
17	Ipomoea setosa Ker Gawl. subsp. pavonii (Hallier f.) J.R.I. Wood & Scotland	Convolvulaceae	Neophyte	Southern America	G bulb	Roadside	1
18	Juglans regia L.	Juglandaceae	Cryptogenic	Western Asia	P scap	Temporary water body/Roadside	5
19	Kalanchoë delagoënsis Eckl. & Zeyh.	Crassulaceae	Neophyte	Southern Africa	Ch succ	Roadside	1
20	Luffa aegyptiaca Mill.	Cucurbitaceae	Neophyte	Southern Africa	T scap	Temporary water body	1
21	Narcissus ‘Cotinga’	Amaryllidaceae	Neophyte	Culton	G bulb	Crop/Shrubland	2
22	Narcissus ‘Erlicheer’	Amaryllidaceae	Neophyte	Culton	G bulb	Roadside	1
23	Nothoscordum gracile (Aiton) Stearn	Amaryllidaceae	Neophyte	Southern America	G bulb	Roadside/Sidewalk	36
24	Oxalis stricta L.	Oxalidaceae	Neophyte	Northern America	H scap	Sidewalk	3
25	Passiflora caerulea L.	Passifloraceae	Neophyte	Southern America	P lian	Roadside	1
26	Portulaca grandiflora Hook.	Portulacaceae	Neophyte	Southern America	T scap	Roadside/Sidewalk	2
27	Prunus armeniaca L.	Rosaceae	Archeophyte	Culton	P scap	Crop	1
28	Prunus dulcis (Mill.) D.A. Webb	Rosaceae	Archeophyte	Feral	P scap	Outcropping rocks/Roadside/Shrubland	7
29	Salpichroa origanifolia (Lam.) Baill.	Solanaceae	Neophyte	Southern America	Ch frut	Roadside	10
30	Sesbania punicea (Cav.) Benth.	Fabaceae	Neophyte	Southern America	P scap	Temporary water body	1
31	Solanum tuberosum L.	Solanaceae	Neophyte	Culton	T scap	Temporary water body	1
32	Tecoma stans (L.) Juss. ex Kunth	Bignoniaceae	Neophyte	Northern America	P lian	Sidewalk	1
33	Tradescantia sillamontana Matuda	Commelinaceae	Neophyte	Southern America	G rhiz	Uncultivated field	1
34	Washingtonia filifera (Linden ex André) H. Wendl. ex de Bary	Arecaceae	Neophyte	Northern America	P scap	Sidewalk	1
						Total	118

Note. Plant life forms (according to the Raunkiaer system) Ch frut, Frutescent chamaephyte; Ch succ, Succulent chamaephyte; G bulb, Bulbous geophyte; G rhiz, Rhizome geophyte; H caesp, Cespitose hemicryptophyte; H scap, Scapose hemicryptophyte; NP, Nanophanerophyte; P lian, Climbing phanerophyte; P scap, Scapose phanerophyte; T scap, Scapose therophyte.

We verified the distribution of taxa within the Natura 2000 network. Some taxa grew in network sites: Beta vulgaris subsp. vulgaris, Cedrus atlantica, Fagopyrum esculentum, Freesia alba, Juglans regia, and Nothoscordum gracile (Table 3). B. vulgaris subsp. vulgaris was found in SAC IT9350145 “Fiumara Amendolea (including Roghudi, Chorio, and Rota Greco)” and in SPA IT9350300 “Costa Viola”, while C. atlantica, F. esculentum, F. alba, J. regia, and N. gracile were only found in the SPA IT9350300 “Costa Viola”. If C. atlantica, F. esculentum, F. alba, and J. regia are considered as “casual”, B. vulgaris subsp. vulgaris tends to naturalize, and N. gracile becomes invasive in other sites where it has been found, also representing a potential threat for protected areas such as SPA “Costa Viola”.

Table 3

Alien taxa found in two sites of the Natura 2000 network in Calabria (Southern Italy, Europe).

ID	Taxon	SAC/SPA	SAC/SPA Code	SAC/SPA Name
5	Beta vulgaris L. subsp. vulgaris	SAC	IT9350145	Fiumara Amendolea (incluso Roghudi, Chorio e Rota Greco)
5	Beta vulgaris L. subsp. vulgaris	SPA	IT9350300	Costa Viola
10	Cedrus atlantica (Endl.) G.Manetti ex Carrière	SPA	IT9350300	Costa Viola
15	Fagopyrum esculentum Moench	SPA	IT9350300	Costa Viola
16	Freesia alba (G.L. Mey.) Gumbl.	SPA	IT9350300	Costa Viola
18	Juglans regia L.	SPA	IT9350300	Costa Viola
22	Nothoscordum gracile (Aiton) Stearn	SPA	IT9350300	Costa Viola

Notes. SAC: Special Area of Conservation [60]; SPA: Special Protection Area [61].

Two species (Araujia sericifera and Washingtonia filifera) are recently included in a list of candidate species to be submitted to the national prioritization procedure for their inclusion in a national list according to Regulation (EU) No. 1143/2014 [62]. Therefore, knowledge of new sites of A. sericifera and the new record of W. filifera for Calabria are very important for their control because they have a detrimental impact on plant communities [63].

Among others, Cenchrus setaceus is rapidly spreading in the regional territory after its first report in 2007 [64]. Indeed, these authors reported C. setaceus (sub Pennisetum setaceum) for Calabria in two locations, both along communication routes, but at a high distance from each other: one along the A2 motorway between Rosarno and Gioia Tauro in the province of Reggio Calabria on the Thyerrenian side, and another along highway SS 106 Jonica near Cropani Marina in the province of Catanzaro on the Ionian side of the region. After several new records of this alien species for Calabria by Musarella et al. [44,50], new individuals have been recorded near the previously observed in Reggio Calabria where they have generated new tufts in the same point [“lungo Raccordo Autostradale 4 di Reggio Calabria prima della galleria Spirito Santo in direzione Sud (Reggio Calabria), roadside, 93 m s.l.m., 21.11.2018, 557933–4218164, obs. et det. V.L.A. Laface et C.M. Musarella”] and a few tens of meters from them [“lungo la SS 106 Jonica presso località Ravagnese (Reggio Calabria), roadside, 38 m s.l.m., 19.11.2018, 558138–4213357, leg. et det. C.M. Musarella (REGGIO)] [44]. According to Brundu [65], only an early detection and rapid eradication (EDRE) of C. setaceus can prevent its rapid spread, for this reason, its continuous monitoring is really important to prevent ecological damage.

Two cultivars of Narcissus used as ornamentals were observed by the authors (Figure A1). Report no. 21 was recorded for two locations where it has multiplied over the years after the first observation in 2013 by Laface and report no. 22 was recorded for the first time at the beginning of 2020 by Musarella. It is likely that they escaped cultivation or were thrown among the waste material from nearby gardens. As to which cultivars they were, there are more than 27,000 daffodils of garden origin registered in the International Daffodil Register and Classified List in 2008 [66]. According to [66], the report no. 21, which has single flowers with solitary flowers, white reflexed perianth segments and an apricot-pink corona, belongs in Division 6 (Cyclamineus) and was recognized as Narcissus ‘Cotinga’. Report no. 22, which has double flowers with white perianth segments with a trace of yellow at the base, belongs to Division 4 (Double flowered) and is referred to as Narcissus ‘Erlicheer’. Regarding their invasiveness, it is important to consider that daffodils rarely spread rapidly and certainly the Division 4 cultivars are sterile, so cannot spread by seed. For this reason, we consider it to not have a detrimental impact on the environment. These are both first records for Italy.

Figure A1

Two different cultivars of Narcissus cv. collected in the Reggio Calabria province. (a) Narcissus ‘Cotinga’ in Piani di Reggio, in grazing-meadow (Photograph VLA Laface); (b) Narcissus ‘Erlicheer’ in Pellaro, in a roadside along a wall (Photograph CM Musarella).

4. Materials and Methods

This research was based on fieldwork carried out randomly and during a well-designed research field for the coordination of monitoring activities of natural and semi-natural habitats of the flora and fauna species of the Natura 2000 Network present in Calabria (see Funding section) from 2018 to 2020 as well as on herbaria and literature surveys. As part of this project, in fact, it was necessary to verify the conservation status of the habitats in accordance with the European Directive [60] as well as in relation to the possible threat or pressure exerted by an alien species on them. Fieldwork consisted of collecting samples of alien plants and identifying them in the laboratory. The collected specimens was stored dried in the herbarium of the Mediterranean University of Reggio Calabria (Italy) (REGGIO, acronym according to Thiers [67]). The investigated area was the whole of Calabria, but the new records concern only the central-southern part.

The taxa in the floristic list are arranged in alphabetical order (Appendix A). Nomenclature, taxa delimitation, and regional distribution are in accordance with Galasso et al. [1] and the following update [45,46,47,48,49,53]. The specimens were identified using Flora Europaea [68,69,70,71,72], Flora d’Italia [73,74,75,76,77], Flora of North America [78], Flora of China [79], and some monographic works [66,80,81,82]. The update distribution of the considered taxa was verified also using [83,84]. Life forms and native range were according to [73,74,75,76,77,85] and by on-field observation. Period of introduction of the taxa recorded were verified on “Portale della Flora d’Italia” [85].

For each taxa, we provide the following information: (1) accepted name; (2) basionym and most relevant synonyms; (3) plant family; (4) period of introduction (archeophyte, neophyte, or cryptogenic); (5) native range; (6) life form; (7) data record in Calabria, Italy, or Europe; (8) current invasiveness status for the region (according to Pyšek et al. [86]); (9) date of observation; (10) discovery localities (municipality, administrative province) (exsiccata and observata) with details on the location (in Italian, according to the information on the specimen labeldata); (11) terminology of Pyšek et al. [86]; (12) decimal degrees geographic coordinates (datum WGS84); (13) growth environment; (14) altitude (meters above sea level–m a.s.l.); (15) legit (or observavit) and determinavit; (16) herbarium where the specimen is stored; and (17) distribution and/or ecological notes when available. For some taxa not documented with a herbarium specimen, we report some pictures where available (Appendix B). All other plants pictures are reported in Appendix B.

5. Conclusions

Although there is adequate knowledge of the alien flora in Italy, not much is known about those in Calabria thus far. As before indicated, Calabrian alien vascular flora amounts to 344 taxa [53,54]. Thanks to this study, it was possible to increase this knowledge by reporting new data on 34 taxa: one (1) confirmation for Calabria, some new for Calabria (21), other new for the Italian Peninsula (1), three (3) for the whole of Italy, and three (3) new for the whole of Europe. Furthermore, a georeferenced location for Araujia sericifera (1) and the invasiveness status for four (4) species already known for the region are reported here for the first time. In total, 28 taxa are new to Calabria. Therefore, we can currently count 373 alien plant taxa for the whole of Calabria. This was possible thanks to the increasing attention to the exotic taxa introduced because, compared to the past, these taxa are invading more and more indigenous habitats, compromising their ecological balance and threatening the survival of native taxa. Works like these are very important because they provide the possibility of identifying a large number of new alien plant species that are spreading worldwide, allowing us to fill in the many gaps at the regional, national and global level.

Nonetheless, it is now clear that knowledge of native species is not enough for the protection of a specific territory. Of additional importance is the knowledge of alien species, their invasive potential, prevention in their introduction (both intentional and accidental), and their immediate eradication (i.e., Cenchrus setaceus, Nothoscordum gracile, Salpichroa origanifolia, and Sesbania punicea, which are spreading very rapidly as invasives). All these actions must be carried out by both the public and private institutions responsible for this, and most notably by citizens that can responsibly act autonomously in this sense. However, the ever-increasing diffusion of taxonomic, biological and ecological knowledge must form the basis for carrying out sustainable policies for the environment.