We interviewed 471 people: 401 in Valmalenco (123 men and 278 women; age ranges went from 10–19 to 90–99) and 70 in Valposchiavo (30 men and 40 women; age ranges went from 20–29 to 80–89). A total of 17,949 URs for 321 taxa were recorded during the field work. Informants from Valmalenco cited 227 taxa belonging to 77 botanical families. The most relevant species were Arnica montana L. (n. of URs = 784; 5.7% of total URs), Vaccinium myrtillus L. (761; 5.5%), and Achillea erba-rotta All. subsp. moschata (Wulfen) I.Richardson (680; 4.9%), while the most cited families were Asteraceae (3360; 24.3%), Rosaceae (1814; 13.1%), and Ericaceae (1216; 8.8%). Concerning the 70 interviews conducted in Valposchiavo, a total of 226 taxa belonging to 65 botanical families were mentioned. The most cited species were Sambucus nigra L. (n. of URs = 227; 5.5% of total URs), Urtica dioica L. (209; 5.1%), and Taraxacum officinale F.H.Wigg. (206; 5.0%), while the most cited families were Asteraceae (765; 18.6%), Rosaceae (467; 11.4%), and Lamiaceae (467; 11.4%). Further information is provided in Table 2.

Both in Valmalenco and in Valposchiavo, the most relevant fields of use were food and medicinal (with 50.4% and 37.2% of total URs in Valmalenco; 53.9% and 32.9% of total URs in Valposchiavo), followed by domestic (VM n = 480, 3.47% of URs; VP 136, 3.31%) and agropastoral (VM 421, 3.04%; VP 233, 5.67%).

The Jaccard similarity index showed that the taxa overlaps between the two studied areas were relatively low (JI = 0.40) compared to studies conducted along the Italian-Slovenian border [22] and in post-Soviet regions [18, 43].

The highest similarity was recorded for food and veterinary species (JI = 0.34) and for medicinal and domestic species (JI = 0.31). VM and VP shared 83 edible plants (83 common species of the total 242 food species recorded in both areas) and 11 veterinary species (11 common species of all the 32 species used in this sector in both area). Medicinal (49 common species of all 157 medicinal species in both area) and domestic plants (33 common species of all the 107 species in this sector in both area) had slightly lower JI value. Agropastoral (20% of all the 103 species in this sector) and recreational species (18% of the 33 species in this sector) showed the lowest JI values (Table 3).

When we compared the uses within each sector for the two area, food uses showed the highest similarity values (JI = 0.31; 185 common uses of the 599 recorded in both area), followed by medicinal uses (JI = 0.22; 90 common uses of the 403 in both areas). Intermediate values were found for veterinary (JI = 0.15; 7 common uses of the 47 in the sector), artisanal (JI = 0.14; 10 common uses on the 70 uses) and domestic uses (25 common uses of all the 173). The use of agropastoral (16 common of the total 137 uses) and recreational (4 common of all the 43 uses) species showed the lowest similarity values (JI = 0.20 and = 0.18, respectively).

Figure 2 shows the taxa with the highest overlap in use diversity, as well as those used only on one of the studied valleys. The taxa with greater number of common uses showed generally more varied uses (Spearman test: R = 0.77; p < 0.01). Of all the reported taxa, 97 (30.5%) had at least one common use; out of these, 48 had 1–2 common uses, 28 had 3–4 common uses, 10 had 5–7 common uses and 11 more than 8 common uses. The taxa with the highest number of common uses were also among the ones with the highest number of URs in both valleys: Urtica dioica (14 common uses; 30% of the total uses, common and exclusive, recorded for this species in both areas); Malva sylvestris L. and Taraxacum officinale (12; 37% and 33%, respectively); Achillea erba-rotta subsp. moschata (11; 34%) (Table S1). Thirty-one % of the uses reported in Valmalenco were common to Valposchiavo while 38% of the uses reported in Valposchiavo were also found in Valmalenco.

3D scatter plot of the taxa with the highest number of URs in Valmalenco (VM) and Valposchiavo (VP); OV: overlaps

For the complete list of plant species cited in Valmalenco and in Valposchiavo, along with the Fields of use for each species, please see Table S1 of the Supplementary Materials. For further information, as a way of example we collected the complete data concerning both common and different uses of 10 species mentioned in Valmalenco and in Valposchiavo in Table 4.

We then focused our attention on similarities and differences found in the different Fields of use. We report the most interesting examples hereafter.

Regarding the food uses, only the category ‘Cooked and preserved in alcohol’ was reported solely on one side of the border, specifically in Valposchiavo (Fig. 3). The uses with the highest overlaps were ‘Flavoring’ (JI = 0.33), ‘Liquor’ (JI = 0.47), and ‘Cooked vegetables’ (JI = 0.28).

3D scatter plot of the recorded food categories in Valmalenco (VM) and Valposchiavo (VP). OV: overlaps. Jaccard’s Similarity values are reported between brackets

Taking into account the areas surrounding Valmalenco and Valposchiavo, Venn diagrams and Jaccard similarity indices in Fig. 4 reflect differences and similarities between the food species recorded in the two investigated areas and those reported in literature sources from Italian [3, 5, 7, 9, 10, 14, 37, 38] and Swiss [39] Alpine areas. Forty-four and 61 food species were specific to Valmalenco and Valposchiavo, respectively (that is, they were not mentioned in the literature source of the neighboring areas). Higher similarity was found with literature on Italian Alpine areas (JI: VM = 0.38; VP = 0.36) compared to Switzerland (JI: VM = 0.26; VP = 0.26).

Food uses. Venn diagrams showing species in common among Valmalenco (VM), Italian Alpine regions (IT) and Swiss regions (SW), and among Valposchiavo (VP), Italian Alpine regions (IT) and Swiss Alpine regions (SW), with related Jaccard’s similarity indices (JI)

In Valmalenco, spontaneous plant species, such as Taraxacum officinale, Urtica dioica, Silene vulgaris (Moench) Garcke, and Chenopodium bonus-henricus L., were commonly consumed as ingredients for traditional dishes, as we thoroughly reported in Milani et al. [44]. Albeit with some local variations, these species were also included in the everyday diet of the inhabitants of Valposchiavo and were thus often cited by the Swiss informants too. Among these shared species, in the Italian Alpine regions and the Swiss Valais territory, we could find, once again, wild species included in the everyday diet as side vegetables (mainly cooked or raw in salads) or important ingredients of first courses, such as Taraxacum officinale, U. dioica, S. vulgaris, and C. bonus-henricus.

One of the species typically collected in Valmalenco is Aruncus dioicus (Walter) Fernald, which is then boiled or steamed as an asparagus (it is also called wild asparagus by the inhabitants of the valley) and immediately eaten or then preserved in oil. One percent of the URs (number of URs = 133) is dedicated to this use that can be found in other Italian alpine neighboring valleys of the province of Sondrio [5, 14], but also in the Western Alps [3]. Interestingly, only 0.2% of the URs collected in Valposchiavo (n = 7) involved the use of this species for culinary purposes, while in the Swiss territory of Valais this species was not mentioned at all [39], a possible indication of influences coming from the Italian side of the border on the territory of Valposchiavo.

Liquors and aromatized grappa were also commonly reported in both valleys, with Achillea erba-rotta subsp. moschata and Artemisia genipi Weber ex Stechm among the most cited species for this purpose. Especially during the first half of the twentieth century, these two species played a key role in the economy of Valmalenco, as a significant amount was collected and sold to pharmacies and liquor distilleries as a means of livelihood [45]. While these species are known and common also in Valposchiavo, their traditional use and collection apparently was never a raw necessity as it once was in Valmalenco, also due to the agricultural activities that more easily sustained the population of the Grisons, as reported by one of the Swiss informants. In fact, this informant also mentioned that in the past, people from Valmalenco could be seen collecting A. erba-rotta subsp. moschata and A. genipi also beyond the Passes, in Swiss territory. These two species were among the most cited species for the production of liquors or flavored grappa in all the considered neighboring territories.

Other important plants used especially in the past for these same purposes were species of the genus Gentiana, both in the Italian and the Swiss regions surrounding Valmalenco and Valposchiavo. The most common species were G. lutea L. and G. acaulis L. [3, 5, 7, 9, 10, 14, 39] but others, such as G. verna L. and G. punctata L., made an appearance in some of the works too [5, 14, 39].

Another interesting example was the case of Prunus spinosa L.: while its sour fruits were known and consumed by the inhabitants of both Valmalenco and Valposchiavo, 71.4% of our Swiss informants cited them as the main ingredient of a local liquor called ‘Parmognulì’ (from the Poschiavino vernacular name for the fruits, ‘Parmògnule’). Considering the neighboring territories, this species was known both in the Italian and the Swiss sides: the fruits were eaten raw or used in liquors or alcoholic preserves throughout the province of Sondrio [5, 9, 14], on the Italian Western Alps [3, 7], and in Lower and Central Valais [39]. In Valmalenco, we recorded only the vernacular name of ‘Raspa boca’ from a single informant, as a way to describe the astringent and sour taste of the unripen fruits. However, the Poschiavino term ‘Parmògnule’ widely used in Valposchiavo to indicate the fruits, seemed closer to the local vernaculars recorded on the neighboring Italian province of Sondrio (‘Primuli’ in Sondalo, [5];’Prúmul’ or ‘Brúmul’ in Valfurva, [9]; ‘Brúmol’ throughout the Stelvio Park, [14]) than the one of Lower and Central Valais (‘Belosai’ [39],), which in turn has a more French influence to it.

The three most reported medicinal species in Valmalencowere Arnica montana (specifically for contusions and muscle and joint pains; n. of URs = 768), Malva sylvestris (as an anti-inflammatory for the treatment of various ailments; n = 479), and Pinus mugo Turra (particularly in case of upper airway problems; n = 470), while the most cited categories of pathology (apparatuses) were musculoskeletal traumas (n. of URs = 1145; n. of species = 30), respiratory disorders (1076; 36), and digestive system problems (892; 36). The most versatile taxa were Thymus spp. with 14 different pathologies treated, Achillea millefolium L. with 13, and M. sylvestris with 12.

In Valposchiavo, the most relevant species were Arnica montana (same uses as in Valmalenco; n. of URs = 96), Urtica dioica (as diuretic and depurative for the whole body; n = 95), and Thymus spp. (for colds and other upper airway problems; n = 90). The first three categories of pathology were respiratory disorders (n. of URs = 385; n. of species = 40), general condition (general anti-inflammatory, tonic, general depurative etc. 385; 40), and musculoskeletal traumas (199; 32). The most versatile species were U. dioica and M. sylvestris, with 9 different pathologies treated each.

Among the 17 treated diseases, only 3 were reported solely in Valmalenco (external parasites, metabolic disorders, and head pain) although at very low UR frequency (Fig. 5); none was cited solely in Valposchiavo (Fig. 5). The highest number of common species was recorded for respiratory disorders (JI = 0.33), followed by musculoskeletal treatments (0.33), digestive system diseases (JI = 0.22), and skin diseases and traumas (JI = 0.27) (Fig. 5).

3D scatter plot of the recorded medicinal categories in Valmalenco (VM) and Valposchiavo (VP). OV: overlaps. Jaccard’s Similarity values are reported between brackets

Concerning ICFs for the categories of pathology, the highest values were recorded in Valmalenco for musculoskeletal traumas and respiratory disorders (both 0.97), followed by digestive system problems, eye problems, and skin diseases and traumas (0.94 for all three).In Valposchiavo, the highest values were recorded for respiratory disorders (0.90), musculoskeletal traumas (0.87), oropharyngeal affections (0.86), and general condition and digestive system problems (both 0.84).

Overall, albeit with some differences between the two valleys, these results suggest that established cultural criteria are implicitly employed by the local populations when selecting medicinal plants in the treatment of these pathologies. Similar results can be found in previous ethnobotanical investigations in neighboring Alpine areas [5, 6, 9, 38]. Further information concerning the pathologies and the ICFs can be found in Tables 5 and 6.

As for the forms of preparation, in both valleys the infusion was the most common (n. of URs in Valmalenco = 2258; n. in Valposchiavo = 569), followed by ‘other preparation’ (i.e., part of the plant applied as it is. 1151; 427) and syrup (587; 191). These were mainly administered either orally or externally.

Comparing the results obtained for Valmalenco and Valposchiavo, and the ones on the Italian [3, 5, 7, 9, 10, 14, 37, 38] and Swiss [40] Alpine regions (Fig. 6), only 18 medicinal species were found specific to Valmalenco and 0 to Valposchiavo. It seems appropriate to mention that this result may also be influenced by the different numbers of informants in Valmalenco and in Valposchiavo. Jaccard indices showed higher similarity values for Valmalenco and Valposchiavo with Italian Alpine areas (VM = 0.26; VP = 0.21) compared with Switzerland (VM = 0.14; VP = 0.14).

Medicinal uses. Venn diagrams showing species in common among Valmalenco (VM), Italian Alpine regions (IT) and Swiss Alpine regions (SW), and among Valposchiavo (VP), Italian Alpine regions (IT) and Swiss Alpine regions (SW), with related Jaccard’s Similarity Indices (JI)

Some interesting examples of peculiar uses were found during the comparison. The macerated oil prepared with the flowering aerial parts of Hypericum perforatum L. was often cited by the informants of Valmalenco as a valid external remedy against musculoskeletal inflammations and pains (n. of URs = 139), or for the treatment of skin traumas, such as burns and sunburn (n. of URs = 77).

While in Valposchiavo this species was widely known for the same purposes, one particular use caught our attention: the red oleolite of St. John’s Wort was also used by five informants (60–89 years old range) as a remedy against ear inflammations, poured warm drop by drop directly in the ears and kept in place with a cotton pad. This particular use of H. perforatum was not reported in any of the ethnobotanical surveys conducted in the Italian neighboring territories nor in Switzerland. It is interesting to underline that not only our five informants were among the elders of the community, but they had also learned the traditional uses of local species mainly through family transmission, with no major influence from books, courses, or the Internet.

Another example concerns Allium cepa L.: while in Valmalenco it was never cited for medicinal purposes, in Valposchiavo it was considered a useful expectorant and antipyretic remedy. The bulbs were sliced and put for an entire night on the nightstand to induce expectoration or tied around the throat against sore throat. In the neighboring Italian alpine valleys of Valfurva, Sondalo, and Stelvio Park, A. cepa was also considered an expectorant remedy, but the bulbs were boiled in milk or used to prepare a syrup, then taken orally to obtain the desired effect [5, 9, 14].

One elder informant told us that slices of onion kept tied at the soles of the feet for three consecutive nights could be a powerful antipyretic remedy. A. cepa was also cited by an informant as an anti-inflammatory remedy for ear inflammation: also in this case, a slice of onion kept in place in the ear would suffice to obtain the desired effect. The same use was recorded in the territory of Stelvio Park [14]. Although A. cepa was mentioned in a work that compared past and current choices in Swiss flora for medicinal purposes, no information regarding the specific use of this species was reported [40].

The resin of Larix decidua (L.) Mill. was known in Valmalenco as ‘lark turpentine’ and used specifically for different skin (n = 17) and musculoskeletal (n = 14) problems. It was described as more fluid compared to the resin of other conifers and was often mixed with animal or vegetable fats (butter, pork fat, oil) to obtain ointments with different degrees of smoothness. The ointments were then applied to the skin, specifically on wounds, as a cicatrizing agent. The raw resin mixed with pork fat (‘sungia’), and sometimes with resin from other conifers too, was also used to prepare a ‘natural cast’ in case of fractures. This cast was considered more efficient than the ones prepared in the hospital, because the lark resin would allegedly keep the muscle from losing its tone and strength.

In Valposchiavo, both the lark resin and the ointment obtained mixing it with fat was called ‘largù’. ‘Largù’ was considered a wondrous astringent remedy to remove splinters by 50% of the informants, and it was even sold in pharmacies with its vernacular name and with the same purpose.

Different medicinal uses of the resin of L. decidua were reported in several different valleys of the Italian side of the border, alternatively similar to the ones in Valmalenco and the ones in Valposchiavo with vernacular names that were reminiscent of the Poschiavino one: in the territory of Stelvio Park (vernacular name ‘largá’, ‘largé’) and in Val San Giacomo (‘laràs’), the resin was mentioned as a useful remedy against infected wounds and fractures [14, 38], while in Valfurva (‘larĝé’) and in Sondalo (‘argaa’) it was the main ingredient in producing an ointment to remove splinters and wooden shards [5, 9]. No information could be found concerning the medicinal uses of the resin of L. decidua in the Swiss neighboring territories.

It is interesting to highlight that, although in Valmalenco the ointment of lark resin was not used specifically as an astringent agent to remove thorns as in the other analyzed areas, the ointment obtained from the resin of another member of the Pinaceae, Picea abies (L.) H.Karst., was cited by two informants with this same use.

Finally, we consider the case of A. erba-rotta subsp. moschata noteworthy. We already mentioned the importance that this species used to have in the past for the economy of Valmalenco and this importance is still reflected in the high number of informants who cited the species and of total URs (percentage of informants = 84.3%; n. of total URs = 680; n. of URs in the medicinal sector = 397).

A. erba-rotta subsp. moschata was well known as ‘taneda’, ‘daneda’, or ‘aneda’, which are all vernacular names used in the different municipalities of the valley, as well as with the common Italian name ‘erba iva’. We easily spotted bundles of erba iva hanging to dry in every household and the decoction of this species was considered a powerful remedy against digestive problems, from dyspepsia to gastritis and even ulcers [45]. A. erba-rotta subsp. moschata is endemic to the Alpine areas and was widely cited also in the other investigations conducted in neighboring valleys and along the Italian Alpine territory [3, 5, 7, 9, 14, 38].

In Valposchiavo, this species was known as well and generally cited for the same purposes (52.9%; 161; 68), but we noticed an important difference: while in Valmalenco this was almost always the first species spontaneously mentioned during the interviews, in Valposchiavo A. erba-rotta subsp. moschata was brought up by the informants almost as an afterthought and only upon inquiring from the members of the research group, usually at the end of the interview (i.e., ‘Do you happen to know a plant named erba iva?’). Additionally, no vernacular name was mentioned for this species in Valposchiavo.

The agropastoral was the third most cited field in Valposchiavo (n. of URs = 233; 5.7% of the total) and the fourth in Valmalenco (421; 3%), and in both valleys it encompassed several activities, such as horticulture (included the preparation of ‘natural anti-parasite’ for the garden), apiculture (especially with the production of the local honey of alpine rose, Rhododendron ferrugineum L.), and animal fodder.

Although most of the species cited during the field work were spontaneous, it is interesting to underline that the 3500 m of height spread within the territory of Valposchiavo were reflected in the selection of some peculiar cultivated species that grow more easily at lower altitudes. Hemp (Cannabis sativa L.; n. of URs = 5, n. of informants = 5) and tobacco (Nicotiana tabacum L.; 19, 19), for example, were commonly cultivated in the past in Brusio [46,