Respondents showed interest in naming mushrooms and describing their uses (gathered or not gathered for food, gathered for non-food uses, poisonous, recognisable or not). On average, 30.76 species were named or recognised per respondent (minimum 8, maximum 43, median 31). Regionally, the average number of named or recognised species per respondent in Žemaitija was 23 (min. 8, max. 35, median 23), in Suvalkija 31.25 (min. 9, max. 41, median 33), in Dzūkija 33.61 species (min. 21, max. 43, median 34), in Northern Aukštaitija 31.83 species (min. 21, max. 41, median 33) and 31.74 species (min. 20, max. 41, median 33) in Eastern Aukštaitija.

Based on the characteristics of the mushrooms and the results of the interviews, we have divided the species shown into six groups: (1) universally popular edible species (collected by ≥ 30% of respondents in every region), (2) regionally or temporarily popular edible species (collected by ≥ 30% of respondents in at least one region, or popularity of which has declined over time), (3) edible species that are not popular in any region (collected by less than 30% of respondents in any region), (4) non-edible species (strongly acrid-tasting, or mildly poisonous, or only used for non-food purposes, or not used at all), (5) poisonous species and (6) species that are rare, protected or newly discovered (Additional materials, Table 1).

Only two of the mushroom species shown—Cortinarius sanguineus and Flammulina velutipes—were not named in any of the regions. The latter was not even mentioned by the respondents as a mushroom they had ever seen, even though it is a very common wood-inhabiting species in the country. In both Žemaitija and Suvalkija, respondents named 37 species, in Dzūkija—39, in Northern Aukštaitija—41 and in Eastern Aukštaitija—45 species. It should be noted that even some mushrooms that were not used for food or other purposes were traditionally known and named. The number of names per species in the region varied from zero to ten, and the number of names applied did not usually correspond with the popularity of the species or even with the use for food. For example, the most prized edible mushroom Boletus edulis was given between one and seven names in the different regions, the very popular Cantharellus cibarius was given between two and three names; meanwhile, the less valued Imleria badia was given between four and ten names, the not consumed Lycopedon spp. were given between two and eight names, and the inedible Tylopilus felleus was given between two and 10 names (Additional materials, Table 1). However, mushrooms that had no economic, medicinal or recreational and aesthetic value were generally not named, even if they were recognised.

Respondents generally did not distinguish between similar species in the genera, for example, Boletus edulis from B. pinophilus and Suillus luteus from S. granulatus. The latter were best distinguished in Eastern Aukštaitija (6 respondents), the former in Dzūkija and Eastern Aukštaitija (16 and 11 respondents, respectively), which is explained by the distribution of pine forests and the higher frequency of B. pinophilus in these ethno-regions. It should be noted that only in these two regions did all respondents clearly distinguish Imleria from Boletus, whereas in the other ethno-regions there were between one to three respondents who identified Imleria badia as one of the Boletus. Leccinum was almost universally distinguished as 'brown-capped' and 'red-capped', and the names of the two groups were different. Only three respondents (all in Suvalkija) did not distinguish between the two Leccinum species. The species of coloured Russula all had the same names and were not distinguished in most regions, with the exception of the acrid-tasting carmine capped species, such as R. emetica, which were reported as inedible, even though they had the same name as the mild-tasting species. However, in Suvalkija, some respondents differentiated Russula by cap colour and to some extent by habitat. Only a small proportion of respondents distinguished Xerocomus subtomentosus from other boletoids, even if they collected them. In Northern Aukštaitija and Suvalkija, some respondents did not distinguish between Tricholoma equestre and T. portentosum, in contrast to Eastern Aukštaitija and especially Dzūkija, where the two species were clearly separated. Some respondents did not distinguish Morchella spp. from Gyromitra esculenta. In all regions, a proportion of respondents did not distinguish Russula delica from Lactifluus piperatus and Armillaria spp. from Kuehneromyces mutabilis, with a higher percentage of distinguishing the latter in regions where Armillaria spp. were popular among mushroom pickers. Gyroporus cyanescens was mostly confused with other boletoids (e.g. Boletus radicans and Tylopilus felleus), except in Dzūkija, though it was not collected there. Suillus bovinus was confused with other Suillus species by some respondents, but it was also best recognised in Dzūkija, although it was not collected there. Agaricus spp. and Macrolepiota procera were attributed to Amanita by some respondents. Only a few respondents clearly distinguished Calvatia from Lycoperdon, their names and recognition stemming mainly from characteristic release of dry spore masses in both genera. Amanita muscaria and A. phalloides were both referred to as musmirės (Amanita) by the majority of respondents, although it was clear from the descriptions that the two species were seen as distinct.

A total of 36 species were consumed for food. Regionally, a total of 27 species were collected for food in Žemaitija, 31 in Suvalkija, 22 in Dzūkija, 29 in Northern Aukštaitija and 32 in Eastern Aukštaitija (regardless of the number of respondents collecting the individual species).

Among the universally popular mushrooms, Boletales dominated, as well as Cantharellus cibarius, Lactarius sect. Deliciosi and coloured Russula species (Fig. 2b).

a Traditionally dried Gyromitra esculenta (Dzūkija). b Fermented mushrooms with prevailing Cantharellus cibarius and Russula spp. (Eastern Aukštaitija). c Harvested Tricholoma equestre (Dzūkija). Photographs: a and b: Vita Džekčioriūtė; c: Žydrūnas Sinkevičius (see acknowledgements)

Fifteen of the mushroom species were only regionally (Fig. 3) or temporarily (and sometimes only temporarily) popular mushrooms. Suilellus luridus was a recognised and popular edible mushroom in Suvalkija and especially in Žemaitija, while in other ethno-regions it was mostly treated as inedible, or was not distinguished from other boletoids by those who collected it.

Percentage of mushroom foragers collecting regionally popular mushroom species in different ethno-regions. Colour scheme refers to individual ethno-regions

In Dzūkija, by contrast, S. luridus was not named by any respondent and was recognised by less than 30% of respondents, which can be explained by the lack of forests suitable for S. luridus in this region. Gyromitra esculenta, a toxic mushroom that requires special preparation before consumption, is still widely collected in Europe. In Lithuania, between 44 and 100% of respondents in different regions admitted to collecting G. esculenta for food (Fig. 2a), except in Žemaitija, where less than 30% of respondents consumed it. Žemaitija was also the region where fewer people recognised the mushroom. Gyromitra esculenta was also among the mushrooms whose popularity was declining, except in Suvalkija and Dzūkija, where nobody admitted to having stopped collecting it. Suillus variegatus was also unpopular and unfamiliar in Žemaitija, where it was recognised by less than 30% of respondents and collected by even less percentage. In Northern Aukštaitija, S. variegatus was recognised and collected by slightly less than half of the respondents, whereas in other regions, it was known and popular. Tricholoma equestre was popular in the pine forest-dominated regions of Dzūkija and Aukštaitija, where it was recognised and admitted to be collected by 94–100% of respondents (Fig. 2c). Žemaitija was an exception—only 13% of the respondents recognised and collected this species.

The situation was similar for Tricholoma portentosum: none of the respondents recognised and collected it in Žemaitija. In Northern Aukštaitija, it was also mostly not recognised and not collected. It was best recognised and collected in Dzūkija; meanwhile in Eastern Aukštaitija, it was less recognised and collected than T. equestre. Calocybe gambosa was popular only in Northern Aukštaitija, where it was recognised and collected by almost half of the respondents. In the other regions, it was identified by very few respondents, with only one respondent in each region collecting it, with the exception of Suvalkija, where no one admitted collecting it. Cortinarius caperatus was well recognised and collected in all regions except Žemaitija. Macrolepiota procera was popular only in Dzūkija and Eastern Aukštaitija. Only one respondent in Dzūkija admitted to having collected Paxillus involutus before. In the other regions, between 35 and 78% of respondents admitted to having collected it. In all regions except Suvalkija, some respondents admitted to have stopped collecting P. involutus. Lactarius torminosus was not collected at all in Dzūkija, and only by two respondents in Žemaitija. In other regions, except Suvalkija, some respondents stopped collecting it. Russula delica was collected in all regions and the number of collecting respondents varied from 20% (Žemaitija) to 48% (Northern Aukštaitija). Lactarius turpis was the most popular in Northern Aukštaitija (collected by 70% of respondents), while in Dzūkija it was not collected at all, although it is very well recognised in all regions, but its popularity has decreased. Armillaria spp. was not collected in Dzūkija, in other regions its popularity ranged from 32% (Eastern Aukštaitija) to 65% (Northern Aukštaitija) of respondents. The popularity and use of Xerocomus subtomentosus and Morchella spp. were difficult to assess, as a large proportion of respondents did not seem to distinguish them from other Boletales and Gyromitra eculenta, respectively.

Gyroporus cyanescens, edible but unpopular with mushroom pickers, was least recognised and not named in Northern Aukštaitija, quite well recognised and distinguished in Dzūkija, but collected by only a few respondents in all regions (Fig. 4), and not collected at all in Dzūkija. Suillus bovinus was also best recognised in Dzūkija, although not collected and worst recognised and not even named in Žemaitija. In other regions it was collected by few people. Agaricus spp. were neither well recognised nor popular, and was not collected at all in Dzūkija. Lactarius piperatus was neither recognised nor collected in Žemaitija, not collected in Suvalkija. In other regions, it was difficult to assess its use due to confusion with Russula delica. Sarcodon spp. were not named (although recognised) in Suvalkija and Northern Aukštaitija, collected by one respondent (in Suvalkija). Hydnum spp. were best identified and collected in Žemaitija (47% identified, 27% collected), in most other regions they were neither named nor collected. Only one respondent admitted collecting Kuehneromyces mutabilis, even that one possibly confused it with Armillaria spp. Lycoperdon spp. were identified and named by the majority of respondents in all regions but were not consumed in any of them. Calvatia gigantea was collected by one respondent, although it was also well recognised everywhere.

Percentage of mushroom foragers collecting unpopular mushroom species in different ethno-regions. Colour scheme refers to individual ethno-regions. Note: Sarcodon spp. and Flammulina velutipes were not included in the graph as they were not shown in one of ethno-regions (see Material and methods)

Mushrooms are mostly consumed in mixtures (different types of mushrooms), and the most popular dish mentioned by all respondents was pre-boiled mushrooms fried with bacon and onions, with the addition of sour cream (Additional materials, Table 3). Mushroom soup and mushroom salad with sour cream were also mentioned. Boletoid mushrooms, in particular Boletus spp., are commonly dried and then used in soups, stews, pies, dumplings and herring dishes, especially for Christmas Eve dinner. Boletus spp., Leccinum spp., Lactarius sect. Deliciosi, Cantharellus cibarius are sometimes eaten separately, either fried or in soups, or pickled when there are enough fruit bodies for a separate dish. Exceptions are the mushrooms of the spring season, which are eaten separately, pre-boiled and fried, and Macrolepiota procera, which is always fried without pre-boiling, either in batter or without it. Mushrooms are also preserved for the winter, although the traditional methods of salting or fermenting have been largely replaced by pickling and freezing. However, the mushroom dishes mentioned by the majority of respondents did not differ much from those described in various books on traditional Lithuanian cuisine and food traditions [18, 48], as well as on regional cuisines [23, 49].

A total of nine medicinal mushroom species were named (Fig. 5). Of these, only Amanita muscaria and Inonotus obliquus (Fig. 6a) were recognised as medicinal mushrooms in all regions, with consumption ranging from 77% of respondents (Dzūkija) to 21% (Northern Aukštaitija) and from 23% (Northern Aukštaitija) to 13% (Žemaitija), respectively.

Mushrooms used as medicinal by the per cent of respondents in the individual ethno-regions. Colour scheme refers to individual ethno-regions. Other Amanitas include A. phalloides and A.virosa

a Alcohol-based extract of Inonotus obliquus and fruit bodies of the fungus used to prepare the extract (Dzūkija). b Alcohol-based extract of Phallus impudicus (Eastern Aukštaitija). Photographs: a: Ernestas Kutorga; b: Vita Džekčioriūtė

Even if not used personally, A. muscaria was recognised and named by the absolute majority of respondents. Inonotus obliquus was also well recognised and named in all regions (53% to 93% of respondents). Phallus impudicus was recognised as medicinal in all regions except Northern Aukštaitija, its use ranged from 53% of respondents (Žemaitija) to 12% (Dzūkija) (Fig. 6b).

Phallus impudicus was most accepted in Žemaitija (100% of respondents). In Dzūkija, however, only two people recognised it and did not have a name for it. Other species were only occasionally mentioned as medicinal mushrooms, except for Gyromitra esculenta in Dzūkija.

Among the other uses of mushrooms, the absolute majority of respondents mentioned Lycoperdon and Calvatia as children's play objects. Respondents over 70 years of age indicated that Fomes fomentarius had been used in the past to bring fire from the church at Easter and for the fire ignition. The mushroom was well recognised and named (between 87 and 100% of respondents in different regions), although the vast majority of respondents used the name which refers to any larger bracket. Two respondents in different regions mentioned the use of F. fomentarius as a fogging agent to calm the bees during honey collection. One respondent mentioned Sarcodon spp. as a fodder additive for cattle, another respondent mentioned Lycoperdon spp. as a fodder additive for pigs. A few respondents in Dzūkija, Northern and Eastern Aukštaitija mentioned that cows and pigs were fed with mushroom cleaning residues and old fruit bodies, unsuitable for consumption. Respondents over 70 years of age mentioned that they had previously used Amanita muscaria to get rid of flies at home.

The analysis of the similarity of the mushroom species collected for food and medicinal purposes showed that the ethno-regions were clustered into three distinct groups (Fig. 7). Two groups depended on the predominant forest types (and, consequently, on the sets of the most common mushroom species): Suvalkija together with Northern Aukštaitija (predominantly hardwood and mixed forests) and Dzūkija together with Eastern Aukštaitija (predominantly coniferous forests). Both groups covered ethnologically different regions. However, Žemaitija formed a distinct cluster that was clearly defined only by local tradition.

Dendrogram of the cluster grouping (similarity) of the studied ethno-regions based on the percentage of respondents collecting sets of mushroom species for food and/or medicine

Of the inedible mushrooms, Tylopilus felleus was the most recognised and named species in all regions (from 73 to 96% of respondents) (Fig. 8), presumably because of its similarity to the prized edible boletoid species and the need to be able to distinguish between them. Chalciporus piperatus was poorly distinguished and not named in Žemaitija and Eastern Aukštaitija, in other regions it was mostly confused with Suillus bovinus. Sarcoscypha spp. were best identified in Northern and Eastern Aukštaitija (78% and 41% of respondents, respectively), and only in these regions was it named, although at least some of the respondents recognised this fungus in other regions but did not name it. Coltricia spp. were best recognised in Dzūkija and Eastern Aukštaitija (88% and 70% of respondents, respectively). They were named in all regions, except in Suvalkija, though 31% of respondents recognised it in this region. The highly toxic Amanita phalloides was recognised by the majority of respondents (63–100%).

Percentage of respondents recognising inedible, poisonous or rare mushroom species in different ethno-regions. Colour scheme refers to individual ethno-regions. Note: Tricholoma joachimii was not included in the graph as it was not shown in one of ethno-regions (see Material and Methods)

Of the rare species, Tricholoma joachimii was best recognised in Dzūkija, where it was recently recorded [50], while in other regions its recognition was mostly questionable, as respondents did not distinguish it from T. equestre (the species was not shown in Žemaitija). Aureoboletus projectellus, a recent arrival in Lithuania and spreading in the Baltic region [51, 52], was doubtlessly identified in Dzūkija and Eastern Aukštaitija, where it is already present, although only one respondent in each of these two regions collected it for food. Notably, only in Dzūkija, where it has already spread, was A. projectellus named. In the other regions, the mushroom was mostly either not recognised or confused with red-capped Leccinum species. Of the three species in the Lithuanian Red Data Book [53] shown to respondents, the results were poor. The recognition of Neoboletus luridiformis was unclear, as most respondents who recognised or even collected this species did not distinguish it from Suillellus luridus. Lactifluus volemus was identified by very few respondents and was only named in Žemaitija and Eastern Aukštaitija. Sarcosoma globosum was best recognised in Eastern Aukštaitija, where it is most commonly found, whereas in Suvalkija it was neither recognised nor named.