Palaeofloristic record of Linnaea borealis during the Mid-Holocene in the Friuli Venezia Giulia plain

Palaeofloristic record of Linnaea borealis during the Mid-Holocene in the Friuli Venezia Giulia plain Jessica Zappa1, Anna Maria Mercuri1, Giovanni Astuti2, Lorenzo Lastrucci3, Paola Torri1, Assunta Florenzano1 1Laboratorio di Palinologia e Paleobotanica, Dipartimento Scienze Vita, Università di Modena e Reggio Emilia, Via G. Campi 287, 41125 Modena, Italy 2Orto e Museo Botanico di Pisa Sistema Museale di Ateneo, Università di Pisa, Via L. Ghini 13, 56126 Pisa, Italy 3Orto Botanico Giardino dei Semplici, Università di Firenze, Via G. La Pira 4, 50121 Firenze, Italy Corresponding author: Jessica Zappa ([email protected]) Academic editor: Lorenzo Peruzzi|Received 1 September 2025|Accepted 6 October 2025|Published 17 December 2025 Citation: Zappa J, Mercuri AM, Astuti G, Lastrucci L, Torri P, Florenzano A (2025) Palaeofloristic record of Linnaea borealis during the Mid-Holocene in the Friuli Venezia Giulia plain. Italian Botanist 20: 149–165. https://doi. org/10.3897/italianbotanist.20.170749 Abstract Glacial relicts represent invaluable biogeographical markers of past climatic oscillations, offering unique insights into the historical dynamics of species distribution and the long-term persistence of biodiversity within refugia. Linnaea borealis, common name Twinflower, is a small suffruticose plant that grows in coniferous and mixed forests at altitudes ranging from 1,200 to 2,100 m a.s.l. This species is considered a relict of the Ice Age, as its current distribution is limited to circumboreal zones of the Northern Hemisphere. In Italy, currently it was observed living only in the mountains in four northern alpine regions (Valle d’Aosta, Piemonte, Lombardia, Trentino–Alto Adige), while fossil pollen records were found in a wetland area in the plain in Friuli Venezia Giulia. The finding in plains (30 m a.s.l.) in strata dated 6,000 years ago, i.e. significantly later than the post-glacial retreat, opens up the question of whether its disappearance did not occur in post-glacial times in the Palù basin, which possibly may have functioned as a refuge area for this species in the lowlands. This study focuses on the first evidence of past presence of this species, previously unrecorded and currently not present, in the Palù basin. Thanks to detailed palynological analyses, pollen grains of L. borealis were identified in Mid-Holocene pollen samples taken from a core drilled in this area. This approach underscores the importance of combining floristic and palynological data to reconstruct the biogeography and ecology of species. In the case of L. borealis, such analyses offer new perspectives on the past presence of this species in areas where it is no longer found today, shedding light on how climate changes during the Holocene may have influenced its distribution. Keywords Biodiversity, Biogeography, Caprifoliaceae, Palynology, Palù basin Italian Botanist 20: 149–165 (2025) doi: 10.3897/italianbotanist.20.170749 https://italianbotanist.pensoft.net Copyright Jessica Zappa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RESEARCH ARTICLE Jessica Zappa et al. / Italian Botanist 20: 149–165 (2025) 150 Introduction Reconstructing the historical distribution of plant species is one of the central challenges in biogeography and historical ecology. Understanding where and how species were distributed in the past is not only crucial for interpreting current ecological patterns, but also for anticipating future responses to climate and anthropogenic changes (Willis and Birks 2006; Svenning et al. 2008). Modern floristic data alone may be insufficient to accurately reconstruct a species’ biogeographical history, as they provide only a static snapshot of current occurrences (Birks 2003). In this context, palynology (the study of fossil pollen) offers a vital temporal perspective on past plant communities, enabling researchers to integrate the spatial resolution of floristic records with a stratified temporal dimension (Moore et al. 1991; Bennett and Willis 2001). This integrated approach provides insights into longterm vegetation dynamics and allows for a more robust reconstruction of past species distributions and habitat shifts. Climatic relicts are the surviving remnants of formerly widespread populations that became isolated due to climatic shifts and consequential habitat degradation (Hampe and Jump 2011). These populations have survived in small refugia, where local environmental conditions have remained suitable, even when surrounding habitats became inhospitable (Woolbright et al. 2014). Among such areas, the Alpine region has historically served as a major refuge, shaping the distribution and diversity of European flora and fauna through repeated glacial–interglacial cycles (e.g., Europe: Taberlet et al. 1998; Eastern Alps: Tribsch and Schönswetter 2003). In fact, along the Pleistocene (2.58 million–11,700 years Before Present), glacial advances fragmented the vegetation cover of the Alps, forcing many plant species into extraor intra-glacial refugia. Some of these taxa, now called glacial relicts, still persist in isolated alpine microhabitats characterised by cool, stable conditions reminiscent of the late Quaternary environments in which they once thrived. Their current disjunct distributions provide biogeographical evidence of glacial expansions and postglacial retreats across the Alpine area (Holderegger and Thiel-Egenter 2009). Numerous arctic-alpine and boreal-alpine species have been studied as classic glacial relicts, mostly with molecular and plant fossil identifications, including the following examples in the Alps and across Europe: Nuphar pumila (Timm) DC. (Bétrisey et al. 2020), Saxifraga oppositifolia L. (Winkler et al. 2012), Eritrichium nanum (L.) Schrad. ex Gaudin subsp. nanum (Stehlik et al. 2002) and the Ranunculus alpestris group (Paun et al. 2008), Carex aquatilis Wahlenb. (Andreas 1951), Dryas octopetala L. (Tralau 1963; Birks 2008), Betula nana L. (Birks 2008). These taxa are among the most valuable bioindicators of stable microclimatic conditions and play essential roles in biodiversity conservation, palaeoecological reconstruction and studies on plant resilience to climate change. In this study, we focus on Linnaea borealis L., a circumboreal species currently surviving as a relict in several valleys of the Italian Alps (Valle d’Aosta, Piemonte, Lombardia, and Trentino-Alto Adige), where it inhabits subalpine acidophilous co- Palaeofloristic record, L. borealis, Mid-Holocene, Friuli Venezia Giulia plain 151 nifer forests with a mossy understorey. These Alpine populations are predominantly clonal, relying on vegetative reproduction, which reflects both a limited capacity for dispersal and a high degree of in situ persistence (Wieberg et al. 2016). A recent work from Pipenbaher et al. (2025), assessed the genetic variability of L. borealis by comparing small, isolated eastern-southeastern Alpine populations with core boreal populations, confirming their status as glacial relicts surviving in specific microhabitats and underscoring the need for targeted conservation strategies. According to Christenhusz (2013) and Thiem and Buk-Berge (2017), L. borealis is a plant belonging to the Caprifoliaceae family; it is an evergreen, stoloniferous dwarf shrub. Its common name, Twinflower, comes from the distinctive inflorescence which is composed by two bell-shaped flowers growing on a forked stem of letter Y shape. Its blooming time is between June and August, in Europe most commonly in June – beginning of July. Blossoms persist for about 7 days, and after pollination the flower develops into a fruit in the form of a small, dry, one-seeded capsule, which lasts 36 days. It spreads by zoochory (seeds are dispersed by birds or by small animals, thanks also to small hair bracts that can attach to animal’s fur). Its reproductive strategy is predominantly clonal, with low production of viable seeds and the pollen dispersion is insect-pollinated. Linnaea borealis is a circumboreal species with ecological adaptations typical of cold, humid bioclimatic zones (see also Suppl. material 1). It exhibits a marked preference for shaded or semi-shaded environments characterised by low light intensity and stable microclimatic conditions. This species typically occurs in subalpine coniferous forests (composed mainly by Picea abies (L.) H.Karst. and Abies alba Mill. with other Pinus species), where it forms part of a moss-rich understorey (with Rhododendron spp. and Vaccinium myrtillus L. underwood). It thrives on podzolic soils that are acidic, moist, and rich in organic matter, particularly humic forest litter in cold and cool climates. These edaphic and microclimatic requirements reflect its status as a climate-sensitive relict, dependent on long-term ecological stability and minimally disturbed forest structures (Wróblewska 2013; Pignatti et al. 2018; Pipenbaher et al. 2025). As a shallow-rooted species, it is particularly susceptible to drought; in dry years, its populations tend to decline, whereas they increase markedly during wetter years (Piękoś-Mirkowa and Mirek 2003). In the past century, numerous localities where this species was once widespread and abundant (such as in Wolin National Park and the Wisełka region in Poland) have been well documented (Piotrowska 1966). Many of these populations are now gradually disappearing, primarily due to changes in habitat conditions. In addition to increasing drought, a major contributing factor is the alteration of forest structure and understory composition caused by anthropogenic destruction of locations (as observed in Serpelice region in Poland; Ciosek et al. 2015) or for the negative effects of the densification of shrub layers of some competitive species such as Vaccinium myrtillus and V. vitis-idaea L. (as observed in Grala-Dąbrowizna region in Poland; Ciosek et al. 2015). Although L. borealis is shade-tolerant, excessive canopy closure and shrub expansion may reduce microhabitat heterogeneity, air circulation, and soil moisture availability, ultimately making conditions unsuitable for its persistence (Niva 2003; Niva et al. 2006; Scobie and Wilcock 2009). These reductions in L. borealis communities are largely the result of Jessica Zappa et al. / Italian Botanist 20: 149–165 (2025) 152 natural succession in the shrub layer and also of some forest management practices (as reported by staff of Wolin National Park, see Thiem and Buk-Berge 2017). Due to its strict ecological and climatic requirements, according to Bartolucci et al. (2018, 2024) in Italy the species is confined to just four northern regions (Valle d’Aosta, Piemonte, Lombardia, and Trentino-Alto Adige) where it is restricted to a few mountain sites at high elevations (from approximately 1,200 to 2,100 m a.s.l.). In particular: (i) in Valle d’Aosta, the species is listed as nearly threatened by Bovio (2016); (ii) in Piemonte, the presence of the species is a recent finding, while the species was previously considered at locally extinct (Selvaggi et al. 2023, 2024); (iii) in Lombardia, it is considered at a moderate extinction risk, and a new locality in the Orobic Alps was also discovered (Cretti and Bona 2015); (iv) in Trentino-Alto Adige, and particularly within the Adamello Brenta Natural Park, it is also considered at a moderate extinction risk (Festi and Prosser 2008) and occurs both inside and outside the park boundaries. Lastly, an interesting aspect of this species concerns the ethnobotanical knowledge. L. borealis has a long history of use in folk medicine across Europe and North America, where it was employed to treat ailments such as shingles, rashes, rheumatism, and menstrual pain, often through decoctions, ointments, or smoke inhalation (Brondegaard 1959; Alm 2006). In Nordic countries, the plant was commonly boiled in water or milk and consumed on an empty stomach, while in North America, indigenous tribes used it for cramps, fevers, and headaches (Moerman 1998). Today, L. borealis is also used in cosmetics for skin care, prompting renewed interest in its phytochemical properties and ongoing pharmaceutical research, particularly in Poland. Pollen attributed to Linnaea borealis was found in the PaluOFF1 core (Friuli Venezia Giulia) between 9,800 and 6,300 cal yr BP (calibrated years Before Present), despite the species current absence and lack of the species in previous records in the area (Pini 2004; Zappa et al. 2023). The comparison between fossil and herbarium pollen, using standard morphological criteria and statistical analysis, confirmed the local presence of the species (Zappa et al. 2025). The aim of this paper is, therefore, to discuss the significance of the presence of L. borealis in the Palù basin during the Mid-Holocene. Pollen from a terrestrial core provides this new information on the species spatial and temporal distribution. By integrating current sources, the research intends to propose the Palù basin as a potential refugium for this species during the Holocene. Materials and methods Study area The Palù basin (30 m a.s.l.), located in the Pordenone province between Caneva and Polcenigo (Friuli Venezia Giulia), is a ca. 100-hectare wetland formed during the late glacial period due to fluvial and tectonic dynamics that led to the creation of a lake, Palaeofloristic record, L. borealis, Mid-Holocene, Friuli Venezia Giulia plain 153 later evolving into a complex system of peatlands, ponds, and rivers (Bassetti and Cavulli 2002; Peresani and Ravazzi 2002). Its sedimentary sequence, spanning from the Last Glacial Maximum (15,000–11,000 yr BP) to the present, preserves a detailed archive of environmental and climatic changes in the southern Friulian Prealps, making it a site of high palaeoecological (Pini 2004; Zappa et al. 2023) and archaeological significance (Micheli et al. 2023). In fact, thanks to the large amount of archaeological evidence, Palù di Livenza was inscribed in 2011 on the World Heritage List of UNESCO – “Prehistoric pile-dwellings around the Alps”. Excavation campaigns, including a Neolithic village, were carried out between 2013 and 2021 under the coordination of Roberto Micheli (Superintendence of Friuli Venezia Giulia) (Micheli et al. 2022). Currently, the land within the Palù basin is primarily used for agricultural purposes, although several natural areas remain preserved (Fig. 1). The surrounding lowland landscape includes vineyards, arable land, pastures, urban settlements, and mineral extraction sites. In contrast, higher elevations (such as the Cansiglio Massif) are predominantly covered by coniferous and mixed forests. The Palù basin holds significant naturalistic value and has been designated as a Biotope since 2018, owing to its remarkable environmental, faunal, and vegetational features, many of which are globally threatened. As a spring-fed wetland, the site plays a crucial role as a reproductive habitat for numerous amphibian species (many of which are nationally or even internationally protected) and are particularly vulnerable to human disturbance. The dominant vegetation at Palù di Livenza belongs to the 147b series (Blasi 2010), which comprises three intertwined phytosociological sigmeta: BuglossoidoOstryo carpinifoliae, Mercuriali ovatae-Ostryo carpinifoliae, and Ostryo carpinifoliaeFraxino orni. Each is characterized by specific assemblages of deciduous trees, shrubs, Figure 1. Corine Land Cover based map showing the main land cover types in Friuli Venezia Giulia with focus on the surrounding of the Palù di Livenza basin and the PaluOFF1 coring site. The map was carried out using QGIS version 3.42 (QGIS Development Team 2009) with the Corine Land Cover 2018 vector data (100 m resolution) as base layer (EAA 2019). Jessica Zappa et al. / Italian Botanist 20: 149–165 (2025) 154 and herbaceous species typical of the pre-Alpine region. The area also includes highvalue spring habitats, forming part of the broader “spring belt” of the Po Plain, where groundwater emerges due to the presence of fine, impermeable sediments (Zappa et al. 2008). These springs sustain a rich mosaic of wetland habitats, including alkaline fens dominated by Cladium mariscus (L.) Pohl and other hygrophilous species, which form distinct vegetational zones around ponds and lakes. Palynological studies on past pollen record In February 2022, a sediment core (PaluOFF1) was manually cored approximately 300 meters from the Palù di Livenza Neolithic site. The coring reached a depth of around 6 m, ending upon contact with the “Argille Azzurre” formation, indicative of the Last Glacial Maximum. Excluding the potentially reworked top layer (55 cm), the 555 cm core was sub-sampled and 54 palynological samples were collected every 10 cm under sterile conditions at the Laboratory of Palynology and Palaeobotany in Modena. Then, 21 samples were selected for pollen analysis based on the sedimentological characteristics of the core. Palynological samples were processed using standard protocols (Florenzano et al. 2012) aimed at removing inorganic matter and concentrating palynomorphs, with Lycopodium tablets added to estimate pollen concentrations. The treatment included deflocculation, acid treatments, acetolysis and heavy liquid separation. Pollen analyses were performed at high magnification (1000×) under optical microscope using keys, atlases and the reference collection of the laboratory (e.g., Reille 1992; Beug 2015). For the purpose of this research only general and selected results will be reported. In particular, the useful sums reported and discussed together with the L. borealis record are: coniferous forests, upland forests, mixed oakwood (the widely spread type of forest present in the basin) and sums of plants related to hygrophilous environment (both trees and herbs). Linnaea borealis distribution We reconstructed the historical and current distribution of L. borealis using peer-reviewed literature on floristic data (occurrence of species, records of species in the environment or in Herbaria), the results of which are reported in Table 1. Furthermore, research on the GBIF platform (Global Biodiversity Information Facility) was carried Table 1. Table providing a summary of the Italian regions where the species occurs, the main reported localities of its populations, the principal vegetation associations and the key bibliographic sources. Region Occurrence Vegetation associations Main references Valle d’Aosta Val di Rhêmes, Valgrisenche Shaded slopes with conifers Conti et al. (2005), Bovio (2016) Piemonte Val d’Ossola (e.g., Valle Devero) Acidic, undisturbed areas Selvaggi et al. (2024) Lombardia Upper Valtellina, Stelvio National Park, Orobic Alps Coniferous woods at 1,600– 2,000 m Conti et al. (2005), Cretti and Bona (2015) TrentinoAlto Adige Renon Plateau, Van Ridanna, Val di Fumo, Val di Tovel Rare; in acidophilous beech and spruce woods Bartolucci et al. (2018); Festi and Prosser (2008) Palaeofloristic record, L. borealis, Mid-Holocene, Friuli Venezia Giulia plain 155 out aimed at identifying places where L. borealis was recorded on the field (in Italy) or is present in herbaria collection (with Italian provenance even if stored in European herbaria). The georeferenced data obtained were then used to create a map using R (R Core Team (2025)) and related packages (Wickham 2016; Pebesma 2018; Chamberlain et al. 2025; Giraud 2025; Massicotte and South 2025). Results The PaluOFF1 pollen record Palynological analyses carried out on PaluOFF1 samples gave robust results. The preservation state of pollen grains in sediment was quite always good, allowing the identification at the lowest possible taxonomic level of pollen grains (Fig. 2). In general, a rich biodiversity was found, with a floristic list which includes 117 taxa, 31 AP–Arboreal Plants and 86 NAP–Non-Arboreal Plants (see also Suppl. material 2). To Figure 2. PaluOFF1 off-site core synthetic pollen diagram. AP includes arboreal pollen (trees, shrubs and lianas), NAP the non-arboreal pollen (herbs). Conifers curves includes Abies, Picea abies, Pinus that are also displayed separately, upland forest are the sum of all conifers + Fagus sylvatica and Betula (displayed also separately), Mixed oakwood includes Acer campestre type, Carpinus betulus, Corylus avellana, deciduous Quercus, Ostrya carpinifolia/Carpinus orientalis type, Fraxinus excelsior type, Tilia platyphyllos type, Tilia cordata type and Ulmus; hygrophilous trees (Alnus, Populus, Salix), hygrophilous herbs (Cyperaceae, Lilium martagon, Lythrum, cf. Pancratium, Paris type, Phragmites australis, Scilla type, Scirpus type, Sparganium emersum type, Typha latifolia type) and hydrophytes (Butomus umbellatus, Myriophyllum, Potamogeton, Sparganium erectum type) are also reported. Depth bars represent 10× exaggeration. Chronology is based on the age-depth model performed on two radiocarbon dates (cal yr BP) and published in Zappa et al. (2025). The diagram was drawn with Tilia software (Grimm 2004). This site is included in the BRAIN database (ID: NFV28; Mercuri et al. 2024). Jessica Zappa et al. / Italian Botanist 20: 149–165 (2025) 156 highlight the main features of the vegetation cover along the core, selected sums of taxa were used, focusing on key groups such as mixed oakwood (the predominant forest type at the site) and hygrophilous trees and herbs, as illustrated in Fig. 2. The pollen record spans 10,000 yrs of vegetation history and was subdivided into five pollen zones through cluster analysis, which grouped samples exhibiting similar vegetation assemblages. Linnaea borealis appears consistently across several pollen zones, from its first occurrence in PAL2a to its last in PAL4a, corresponding to a chronological interval between 8,600 and 4,200 cal yr BP. Linnaea borealis specimen in Italy from floristic surveys and herbarium data To obtain an overview of the species’ records in Italy, the starting point was the collection of reports and bibliographic references found on Acta Plantarum (https://www. actaplantarum.org/) and related entries. A summary of the species presence on the field is reported in Table 1. Subsequently, a search on the GBIF (https://www.gbif. org/) allowed for the identification of occurrences of Linnaea in Italy (both herbarium specimens and field observations from the scientific community). The research gave 119 records, 94 of which are georeferenced and could be included in the elaborated map (Fig. 3). One record was excluded as it was determined to be erroneous. This analysis provided evidence of the current and limited distribution of the species within the national territory. Figure 3. Local occurrence of Linnaea borealis in Italy. The elaborated map includes the 93 georeferenced records found. 81 records derive from observations in the field and 12 derive from historical records documented in herbaria. Data were retrieved from GBIF.org (https://doi.org/10.15468/dl.exupdc, accessed on 03rd October 2025) and were elaborated using R. Occurrence points are displayed with transparency, allowing those underneath to remain visible when they are close in space. As points overlap due to their proximity, their shades intensify. Palaeofloristic record, L. borealis, Mid-Holocene, Friuli Venezia Giulia plain 157 Discussion Present day distribution of Linnaea borealis in Italy The integrated approach that merged research on bibliographic sources with quantitative georeferenced occurrence data on the GBIF platform allowed for the construction of a picture of the species’ national presence. The results confirmed that Linnaea borealis is currently confined to a few, geographically scattered locations, primarily in montane and subalpine environments in northern Italy. Both herbarium specimens and modern field records corroborate a distribution pattern that is highly fragmented and restricted in extent. This limited geographic range emphasise the rarity of L. borealis within the Italian flora. Its patchy distribution raises important questions about the environmental variables and factors that have allowed the species to persist in certain microhabitats while disappearing from others. Unlike in Poland, where several studies have shown that the decline of Linnaea communities is linked also to anthropogenic pressures on the landscape (Ciosek et al. 2015), no specific research is currently available in Italy to investigate the causes of this decline in areas where the species has persisted as a glacial relict. The current distribution of this species in Italy appears to be influenced by only ecological and climatic factors. This highlights the need for further investigation into the roles of microclimatic stability and specific habitat characteristics in the areas where the species persisted or persists. In this context, reconstructing its past occurrence and analysing the composition of the plant communities that coexisted with it are essential steps toward understanding the environmental conditions that have supported its long-term survival in some areas. Palaeoecological context and role of the Palù basin as a refugium area The presence of Linnaea borealis in palaeoecological records from Friuli Venezia Giulia offers a unique opportunity to investigate climatic and ecological dynamics in the Mid-Holocene landscape. As a cold-adapted species, L. borealis serves as a valuable indicator of past climatic conditions in the study site. In Italy, several glacial refugia have been identified through palaeoecological and palynological evidence, including the Euganean Hills where the persistence of Castanea sativa Mill. during the Last Glacial Maximum has been documented (Krebs et al. 2004). According to Holderegger and Thiel-Egenter (2009), glacial refugia can be broadly categorised into three types: high-altitude nunataks, peripheral refugia, and lowland refugia. Among these, lowland refugia are considered particularly important for the survival of cold-adapted mountain taxa, as they may have offered microclimatic stability and ecological continuity during periods of glacial advance and subsequent climatic oscillations. The Palù basin, due to its geomorphological setting and hydrological features, may represent one such lowland refugium during a central Mid-Holocene phase. 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Quaternary 6(2): 1–34. https:// doi.org/10.3390/quat6020034 Zappa J, Torri P, Astuti G, Lastrucci L, Mercuri AM, Florenzano A (2025) Rare species in past pollen records and herbarium specimens: Linnaea borealis L. lived in north-eastern lowlands in Italy during the Neolithic. Review of Palaeobotany and Palynology 342: e105398. https://doi.org/10.1016/j.revpalbo.2025.105398 Zappa L, Gasparo D, Lorenzutti D (2008) Biotopi delle risorgive, torbiere e paludi della bassa Pianura Friulana. Regione Autonoma Friuli Venezia Giulia, Trieste. Supplementary material 1 Summary of the ecological requirements of Linnaea borealis in its typical environment in the Northern Hemisphere where it is commonly distributed nowadays Authors: Jessica Zappa, Anna Maria Mercuri, Giovanni Astuti, Lorenzo Lastrucci, Paola Torri, Assunta Florenzano Data type: docx Explanation note: Data summarised from Pignatti et al. (2018); POWO (2025); Thiem and Buk-Berge (2017). Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited. Link: https://doi.org/10.3897/italianbotanist.20.170749.suppl1 Supplementary material 2 Table reporting all 117 taxa found in the 21 samples of PaluOFF1 pollen sequence divided between Arboreal Plants (AP) and Non-Arboreal Plants (NAP) Authors: Jessica Zappa, Anna Maria Mercuri, Giovanni Astuti, Lorenzo Lastrucci, Paola Torri, Assunta Florenzano Data type: docx Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited. Link: https://doi.org/10.3897/italianbotanist.20.170749.suppl2