VERBENA BONARIENSIS (VERBENACEAE) ADVENTIVE IN ITALY

Abstract

Among the species of Verbena L. cultivated in Italy Traverso (1) reports: V venosa Gilles, V tenera Sprengel (= V. pulchella Sweet.) and the horticultural hybrid V I?Jbrida Hort. (=V. hortensis Hort.). No trace of V. bonariensis L., that is reported about 60 years later as naturalized in Tuscany (2). In the Herbarium Centrale !talcum (Fl) are housed specimens collected in Piedmont and Tuscany, labelled as V. venosa - taxon considered a variety of V. bonariensis. V. bonariensis, as indicated by the specific epithet, is a South American species, herbaceous, usually perennial, also cultivated as an ornamental. Several varieties and wild lforms are known of this taxon. The International Plant Names Index (IPNI) records: V bonariensis f. albiflora Moldenke, V. bonariensis var. brevibracteata Kuntze, V. bonariensis var. conglomerata Briq., V bonariensis f. gracilis (Cham.) Voss., V. bonariensis var. hispida Moldenke, V. bonariensis var. litoralis Hook., V. bonariensis var. longibradt?ata Kuntze, V. bonariensis var. rigida (Spreng.) Kuntz, V. bonariensis f. robustior Chodat, V bonariensis f. venosa (Gillies & Hook.) V oss. This species is native of S. America (Argentina, Brasile, ]Paraguay and Uruguay) (3, 4) and introduced in the USA (5), Azores, Great Britain, Canary Islands, Portugal, Madeira (6) and in Italy, as reported above, in Tuscany, in Tombolo Pisano (PI) (2, 7, 8) and in Liguria (8). Some considerations on the tendency of naturalization of the species in Sicily (9) where accidentally misinterpreted as the report of naturalization in the region (10, 11). This record was neglected in the subsequent floras and checklists (7, 8, 12, 13). Recently we verified the spontaneous occurrence of v~ bonariensis at the edges of a channel, in the southern outskirts of the city of Palermo (Sicily). This population, referred to V. bonariensis var. hispida, is made up of about 100 vigorous and perennial individuals with tendency to expand, actually, in the same area. The taxonomic identity of the Tuscan populations is different. In this region, it is known from Tombolo Pisano (2) as well as from Florence as documented by specimens collected in the square in front of the rail station of S. Maria Novella (Raimondo et Domina, 21/06/2012, PAL), in the fenced area for works of rearrangement of the square. In comparison with the population from Tombolo Pisano, referred to the nominal type, the population from Florence looks like annual and belonging to a diffe1rent variety, also in comparison with the Sicilian one. The recent discovery in Sicily as well as increasing the 11uota of adventitious exotic vascular flora of the island, confirms the tendency of the species to spread further in. the national territory.