Contribution to the floristic knowledge of Sillaro, Santerno, and Senio high valleys (Toscana, Italy)

The inventory of the taxa collected during the annual field trip of the working group for Floristics, Systematics and Evolution of the Italian Botanical Society is reported. The field trip was held in 2019 along the Sillaro, Santerno, and Senio high valleys located in Toscana (central Italy). The flora documented for the studied area amounts to 492 specific and subspecific taxa (including five hybrids), belonging to 254 genera and 77 families. Bromopsis caprina, Ophrys appennina, O. classica, Polygala flavescens subsp. flavescens, and Pulmonaria vallarsae subsp. apennina were the only five Italian endemics found in the study area, whereas 28 alien taxa were detected. Finally, nine taxa (seven native and two alien) have to be considered as new records for the regional flora of Toscana.


Introduction
The working group for Floristics, Systematics and Evolution of the Italian Botanical Society has been active in increasing the floristic knowledge of poorly known areas of Italy (e.g., Bartolucci et al. 2019;Stinca et al. 2019, and literature cited therein). Territories to be investigated have been generally selected based on the low number of published floristic studies, as summarized in the map of floristic knowledge of Italy (Scoppola and Blasi 2005).
Here we present the results of the field trip held in 2019 in Toscana, selecting territories poorly known based also on the analysis of the floristic knowledge reported in the online database Wikiplantbase #Toscana D'Antraccoli et al. 2018;Peruzzi and Bedini 2020+).

Study area
Seemingly based on the work published by Zangheri (1966), the explored territory partially falls within an area reported by Scoppola and Blasi (2005) as "well known", and partially considered with a "general knowledge". However, according to the Wikiplantbase #Toscana database (Peruzzi and Bedini 2020+), only 327 floristic records, referring to 248 taxa, were reported for this area. About 13% of these records derived from Zangheri (1966), and 50% derived from old historical literature (Caruel 1860-1864; Baroni 1897Baroni -1908. Recent floristic data are available for surrounding areas, as Sasso di Castro-Monte Beni (Viciani et al. 2008(Viciani et al. , 2012Peruzzi et al. 2009).
The study area includes the high valley of the rivers Sillaro, Santerno, and Senio, located in the province of Florence (municipalities of Firenzuola and Palazzuolo sul Senio) in the north-eastern part of Toscana, at the boundary with Emilia-Romagna (Fig. 1). The altitude ranges from 250 m a.s.l. at the Santerno river near Castiglioncello Figure 1. Study area and localization of sampling sites. Dotted line represents the boundary between the municipalities of Firenzuola (westwards) and Palazzuolo sul Senio (eastwards). For details on the sample sites, see Table 1. to 900 m a.s.l. at Passo del Parietaio. From the geological point of view, the study area is characterized by a marly-arenaceous and marly-limestone (turbidite) sedimentary complex of Medium Miocene, with localized outcrops of ophiolite (Regione Toscana 2019).
According to the classification of Rivas-Martinez et al. (2004) and Pesaresi et al. (2017), the study area is characterized by a temperate continental submediterranean bioclimate, belonging to the vegetation series Acero obtusati-Querco cerridis sigmetum (De Dominicis et al. 2010a, b). Indeed, the current forest vegetation is dominated by broad-leaved deciduous trees (mainly Quercus cerris L.). Other vegetation types occurring in the study area include rocky areas with therophytic communities, ophiolitic outcrops, pastures with mixed shrubs, badlands ('calanchi') and riparian zones.

Sampling and identification
In order to optimize the sampling, 12 sites were selected basing on 3 criteria: (a) to maximise the environmental heterogeneity among sampling sites, (b) to fall in the less-explored areas according to the available floristic knowledge, and (c) to ensure the sampling representativeness of all the tree valleys (Table 1). The sites were preliminarily investigated on March 20 th -22 nd and May 1 st 2019 by the organisers, then sampled during the period May 15 th -18 th 2019 by all participants. A comparative revision of critical collections and of unidentified specimens collected during the field work was carried out at the University of Pisa on February 5 th -7 th 2020.
The nomenclature of taxa follows the updated checklists of the vascular flora native ) and alien  to Italy and subsequent updates summarised in the Portal to the Flora of Italy (2020+; see also Martellos et al. 2020), except for native hybrids, not considered in the above-mentioned checklists. In the floristic list (Suppl. material 1, Part 3), the systematic order of the families follows Bartolucci et al. (2018) and Galasso et al. (2018). Within each family, taxa are ordered alphabetically. For each taxon, after the accepted scientific name, the following information is reported: endemic, cryptogenic and alien status, sampling locality, herbarium in which the collection is conserved (Suppl. material 1, Part 2). Abbreviations or symbols used in the floristic list are: E Italian endemic (according to Peruzzi et al. 2014Peruzzi et al. , 2015Bartolucci et al. 2018; Portal to the Flora of Italy 2020+); A Alien taxon and its status in Toscana: CAS (casual), NAT (naturalized), INV (invasive)]; C Cryptogenic taxon (doubtfully native taxon, whose origin of occurrence in Italy is unknown); N New record for the flora of Toscana.

Results
During the field investigations a total of 2,860 specimens were collected, belonging to 492 species and subspecies, 254 genera, and 77 families (Suppl.   Table 1. All photographs by L. Peruzzi.

Discussion
Among the 492 species and subspecies identified in this work, five are Italian endemics that occur in many other Italian regions, and are included in the Red List of the Italian endemic flora (Orsenigo et al. 2018(Orsenigo et al. , 2020 as LC ("Least Concern") with the exception of Polygala flavescens subsp. flavescens, which is reported as DD ("Data Deficient"). Among them, Bromopsis caprina was so far reported only for Lazio, Abruzzo, Campania, Basilicata, and Calabria ). This species was found only in a thermophilous rocky environment at the site 1A.
Concerning the native flora, besides B. caprina, six taxa are new for Toscana . Crepis albida Vill. subsp. albida, found in the site 1A, reaches in this region its eastern distribution limit, occurring in France, Germany and in Italy only in Piemonte and Liguria (Greuter 2006+;Bartolucci et al. 2018). Potentilla neglecta occurs in Italy in Veneto, Trentino-Alto Adige, Abruzzo, and Lazio . It was found in the site 2D, growing on ophiolitic rocks. In the same locality, we also collected Potentilla pusilla, growing in a pasture with ophiolitic outcrops. This species reaches in Toscana its southern distribution limit, occurring in Italy from Valle d'Aosta to Emilia-Romagna . Pyrus nivalis was considered as native to Italy by Kurtto (2009), whereas Bartolucci et al. (2018) consider it as cryptogenic in Puglia and non-native in Trentino-Alto Adige. Only few individuals were found in the Santerno Valley (site 3B). Finally, still in site 2D we also collected Taraxacum limosicola and Hypochaeris laevigata. The former species belongs to Taraxacum sect. Palustria (H.Lindb.) Dahlst. (Kirschner and Stepánek 1998) and was so far reported only for Emilia-Romagna in Italy, from an area actually close this new locality (Peruzzi and Carlesi 2011). Hypochaeris laevigata reaches in Toscana its northern distribution limit, occurring in Sicily, Sardinia, Calabria, Basilicata, and Puglia (doubtful in Campania, Bartolucci et al. 2018 (Rossi et al. 2013;Orsenigo et al. 2020) as LC.
Among native species, the following 21 taxa are reported for the first time for the province of Florence ( Twenty-eight out of the 492 identified taxa (5%) are non-native. Two of them are new for the flora of Toscana : Campanula portenschlagiana and Rumex cristatus.
Campanula portenschlagiana is native to south-eastern Europe, and it was reported for the first time as alien in Italy for Lombardia (Banfi and Galasso 2010), and later reported as casual for Trentino-Alto Adige, Veneto, Emilia-Romagna, Umbria, and Abruzzo ). This species grows on an urban wall in the village of Piancaldoli, in the Sillaro valley (site 2E). Rumex cristatus is native to Balkans, and it was reported as cryptogenic in Sicily, but as invasive or naturalized alien in several other Italian regions (Galasso 2008;Galasso et al. 2018). We found only few plants colonizing the edge of a route in the village of San Pellegrino, in the Santerno valley (site 1A).