Acta Botanica 2-2016 - za web.indd 206 ACTA BOT. CROAT. 75 (2), 2016 Acta Bot. Croat. 75 (2), 206–209, 2016 CODEN: ABCRA 25 DOI: 10.1515/botcro-2016-0022 ISSN 0365-0588 eISSN 1847-8476 Short communication Phytolacca acinosa Roxb. (Phytolaccaceae), a new alien species in the Croatian fl ora Valentina Borak Martan1, Renata Šoštarić2* 1 Kamaufova ulica 10, HR- 10000, Zagreb, Croatia 2 University of Zagreb, Faculty of Science, Department of Botany with the Botanical Garden, Marulićev trg 20/II, HR- 10000, Zagreb, Croatia Abstract: Phytolacca acinosa Roxb., an East Asian plant species naturalised in many parts of the European continent, has been recorded for the fi rst time in Croatia in two anthropogenic habitats in Varaždin city (NW Croatia). This study reports the newly discovered localities and presents the characteristics of the new alien species in the fl ora of Croatia. A determination key is given for Phytolacca taxa registered in Croatia and neighbouring countries. Keywords: alien plants, Croatia¸ Phytolacca acinosa, Varaždin * Corresponding author, e-mail: rsostar@biol.pmf.hr Introduction Phytolacca L. is the largest genus of the family Phyto- laccaceae, with a number of species, ranging from 25 (De- quan and Larsen 2003, King 2011) to over 35 (Willis 1966). The genus is distributed worldwide, is nearly cosmopolitan and mostly native to South America, with a few species in Africa and Asia (Dequan and Larsen 2003). Several species are found in cultivation and occasionally escape and be- come naturalised (King 2011). According to Drake (2009), on the List of Alien Species in Europe there are six Phytolacca species: Ph. acinosa Roxb., Ph. americana L. (syn. Ph. decandra L., Ph. vulga- ris Crantz), Ph. dioica L. (syn. Pircunia dioica (L.) Moq.), Ph. esculenta Van Houtte, Ph. heterotepala H. Walter and Ph. polyandra Batalin. In Euro+Med PlantBase (2015), the occurrence of Ph. pruinosa Fenzl in Cyprus, Lebanon and Syria is quoted. In Europe, the most commonly recorded species from the genus is Ph. americana, originating from North Ameri- ca and widely naturalised in southern Europe, locally also in western and central Europe (Webb and Akeroyd 1964). Unlike Ph. americana the species Ph. acinosa is much less common in Europe (Wyrzykiewicz-Raszewska 2009) and it is of East Asian origin. Ph. acinosa is native in China, East- ern Asia (Japan, Korea, Taiwan), the Indian Subcontinent and Indo-China (Dequan and Larsen 2003). It was brought to Europe as a vegetable as well as an ornamental plant (Wyrzykiewicz-Raszewska 2009). According to available literature, the occurrence of Ph. acinosa has been reported in several countries: Belgium (Alien Plants of Belgium 2015, Daisie 2015, Q-bank 2015), Denmark (Daisie 2015, Q-bank 2015), Bulgaria (Q-bank 2015), Slovenia (Lešnik 2009), Sweden, United Kingdom, Netherlands (Q-bank 2015) and France (Daisie 2015). Con- sidering the species Ph. esculenta as a synonym of Ph. aci- nosa, the species has also been recorded in Austria (Essl 1998, Q-bank 2015), Germany (Jäger et al. 2013, FloraWeb 2015), Switzerland (Info Flora 2015), in the Czech Repub- lic (Pyšek et al. 2012), Romania (Webb and Akeroyd 1964, Q-bank 2015) Hungary (Balogh 2005) and Bulgaria (Zie- liń ski et al. 2012). Taxonomical status of the species Ph. acinosa and Ph. esculenta has been the subject of several discussions. Ac- cording to Webb and Akeroyd (1964) the name Ph. acinosa is a synonym of the species Ph. esculenta, while for Clem- ent (1982) there are the clearly separate species, Ph. acino- sa and Ph. esculenta (Tab. 1). Recent taxonomists (see for instance Dequan and Larsen 2003) tend to include all east- ern Asian’related taxa that are cultivated for ornament (Ph. esculenta and Ph. latbenia Buch.-Ham. H. Walter) in a broadly circumscribed Ph. acinosa (Alien Plants of Belgium 2015). In Croatia, Ph. americana is reported in cultivation and naturalised (Nikolić 2014). This species is invasive in Croa- tia (Nikolić 2015) and in some other European countries like France (Dumas 2011), Italy (Siniscalco et al. 2011), Portugal (Invasoras 2015), Switzerland (Wittenberg 2005), Greece (Arianoutsou et al. 2010), Czech Republic (Pyšek et al. 2012) and Bulgaria (Petrova et al. 2013). So far, no other species of the genus have been recorded in the territory of the Republic of Croatia. PHYTOLACCA ACINOSA IN CROATIA ACTA BOT. CROAT. 75 (2), 2016 207 Material and methods The city of Varaždin is the county town of Varaždin County and after Zagreb it is the second biggest city in the north-west of Croatia with 46,946 inhabitants (Fig. 1). Ac- cording to Koppen’s climate classifi cation, the broad Va ra ž- din area has a temperate humid climate with warm summers (Cfa) (Šegota and Filipčić 2003). The forest community of sessile oak and common hornbeam (Querceto-Carpinetum orientalis) (Horvatić 1967) would be the zonal vegetation but recently has been transformed into various kinds of an- thropogenic and semi-natural vegetation due long human infl uence. Plant identifi cation was done according to Webb and Akeroyd (1964) and Clement (1982). The plants were pho- tographed with Canon digital camera and geocoding of the locations was performed with use of a GPS device. Results and discussion During a fl oristic investigation of Varaždin in 2014 Ph. acinosa was found at two localities. At the fi rst location (GPS coordinates: 5601192, 5131810) a single specimen was recorded on June 8th 2014 in a landfi ll for various types of waste (occasional fi re site). On August 11th 2014 two specimens were found at the second location (GPS coordi- nates: 5603637, 5129550) in the green area around a build- ing (under a fi r) (Fig. 1). As the taxonomical status of the species Ph. acinosa and Ph. esculenta is still a matter of discussion (Webb and Akeroyd 1964, Clement 1982, Tab. 1), we consider both opinions in the analysis of specimens found in Varaždin. The material had all characteristics of the species Ph. acinosa s. str., except the anther colour. According to Clem- ent (1982) the anthers of Ph. acinosa are white, while our specimens had pink anthers. Something similar was noticed in Belgium where collections of the Ph. acinosa group are usually more or less intermediate between Ph. acinosa and Ph. esculenta: infl orescence axes are often scabrid-glandu- lar (as in Ph. acinosa) but the fl oral characters resemble Ph. esculenta (Alien Plants of Belgium 2015). Whether this in- termediate characteristic manifests possible hybridization is not quite clear and further investigation should give the an- swer. Ph. acinosa s. str. (Fig. 2) is a perennial, growing to a height of 1.5(–3) m (Nienaber and Thieret 2003). Roots are thick, fl eshy. Stems are erect, green or reddish purple, lon- gitudinally grooved, fl eshy, branched (Dequan and Larsen 2003), naked, juicy, branching in the upper part (Wyrzykie- wicz-Raszewska 2009). Leaves are spirally arranged, leaf blade is elliptic or lanceolate-elliptic, 10–30 cm long, and 4.5–15 cm wide. Leaf base is cuneate, apex acuminate or sharply pointed. Petiole is 1.5–3 cm long (Dequan and Larsen 2003). Numerous, densely clustered flowers form a cylindrical raceme of 15–20 cm in length, which grows sympodially and is erect not only during flowering, but also during fruiting. Flowers are radial, bisexual, of approx. 8 mm in diameter, growing from axils on peduncles 6–10(13) mm long. The simple perianth is composed of five petaloid sepals, initially white in colour, later changing into green to become purple-red during fruit ripening. Sepals are ellipti- cal to ovoid, 3–4 mm in length and 2 mm in width. After pollination of flowers they do not drop, but tilt backwards. There are 8–10 stamens, equal in length to the perianth, fi l- aments are persistent, white, subulate, wider at the base with pinkish, elliptical anthers. The pistil of hypogynous fl ower is composed of 7–15 free carpels. The fruit (Fig. 2), generally defined as a berry, is juicy and composed of 7–15, most often eight, adjacent single-seeded berries, forming a compound berry, approx. 7 mm in diameter. Each berry has Fig. 1. Localities with coordinates of Phytolacca acinosa Roxb. in Croatia. Tab. 1. Differences between Phytolacca esculenta Van Houtte and Phytolacca acinosa Roxb. according to Clement (1982). Flowers characteristics Ph. esculenta Ph. acinosa Pedicels and infl orescence axis almost glabrous scabrid-glandular Perianth white greenish white to pinkish Anthers pink white Fig. 2. Phytolacca acinosa Roxb. in location number 2 (Photo by V. Borak Martan). BORAK MARTAN V., ŠOŠTARIĆ R. 208 ACTA BOT. CROAT. 75 (2), 2016 an excrescence on the top, a remnant of the style. At matu- rity fruits are shiny purple-black. Seeds are kidney-shaped, smooth, slightly 3-angulate, approx. 3 mm in length (Wyr- zy kiewicz-Raszewska 2009). All three specimens have been found in anthropogenic habitats, similar to cases in the neighbouring countries (Essl 1998, Lešnik 2009, Zieliński et al. 2012). Ph. acinosa is a gradually spreading, locally naturalised garden escaper. It most often occurs in gardens or parks (under trees or shrubs, foot of walls), in cemeteries or in urban wastelands. Ph. acinosa often occurs in single specimens but bigger local populations are increasingly recorded (Alien Plants of Bel- gium 2015). Ph. americana survives in most environments, in woodlands, pastures, fi elds, forest margins and disturbed sites such as ornamental landscapes, urban waste areas (Di Tomaso et al. 2013) so it is possible to fi nd both species in the same type of habitat. According to the available litera- ture Ph. acinosa always is a much smaller plant (rarely ex- ceeding 100 cm) with an erect infl orescence and broader leaves (Wyrzykiewicz-Raszewska 2009, Alien Plants of Belgium 2015) and fruit composed of eight free segments (representing the eight carpels) and erect infl orescences, which remain erect even after the ripening of the fruits (Petrova et al. 2013). The specimen found at locality number 1 was burnt down during a fi re in the habitat, whereas the other two specimens found at locality number 2 survived through the winter, showing that they are adjusted to a moderate conti- nental climate. The same was also noticed in Slovenia. Ac- cording to Lešnik (2009) Ph. acinosa is a perennial and it recovers from the buds on a thickened root. Since it is the fi rst fi nding of the species Ph. acinosa in Croatia, it is necessary to follow its spread so it can be clas- sifi ed according to criteria applied for alien species, estab- lished by Richardson et al. (2000) (casual plants, natu- ralised plants, invasive plants) and adjusted for Croatia according to Mitić et al. (2008). According to the above stated criteria, the mentioned species has been already natu- ralised in several countries of Europe: Switzerland (Witten- berg 2005), Hungary (Balogh 2005), the Czech Republic (Pyšek et al. 2012), Belgium (Alien Plants of Belgium 2015) and Germany (FloraWeb 2015). In neighbouring Hungary the occurrence of both species (Ph. acinosa and Ph. escu- lenta) has been recorded (Balogh 2005). Ph. esculenta is considered an invasive alien species in Hungary (Balogh 2005, Tiborcz et al. 2012), so it is important to emphasise the possibility of the species spreading into the territory of the Republic of Croatia. Determination key for Phytolacca species in Croatia and neighbouring countries: 1 Carpels 7–15, usually 8, free; racemes erect in ripening; 8 single seed berries forming a compound berry; leaves broadly ovate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 Carpels 10, united; nodding racemes; typical single berry (10-seeded); leaves ovate-lanceolate . . . Ph. americana 2 Flower pedicels and infl orescence axis almost glabrous; perianth white; anthers pink . . . . . . . . . . . Ph. esculenta 2 Flower pedicels and infl orescence axis scabrid-glandular; perianth greenish white to pinkish; anthers white . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ph. acinosa References Alien plants of Belgium, 2015: Retrieved May 15, 2015 from: http://alienplantsbelgium.be/content/phytolacca-acinosa Arianoutsou, M., Bazos, I., Delipetrou, P., Kokkoris, Y., 2010: The alien flora of Greece: taxonomy, life traits and habitat prefer- ences. 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