A comparative ethnobotany of Khevsureti, Samtskhe-Javakheti, Tusheti, Svaneti, and Racha-Lechkhumi, Republic of Georgia (Sakartvelo), Caucasus

Georgia is situated between latitudes 41° and 44° N, and longitudes 40° and 47° E, with an area of ca. 70000 km². Georgia politically associates with European Union and takes part in all major programs of European development and cooperation. However, Georgia’s geographical location depends how the boundary between Southeastern Europe and West Asia is perceived. Most commonly, this boundary is defined as the Main Range of the Greater Caucasus. In this case, Georgia, however small, appears as a transcontinental country with its larger part located south to this divide (i.e., in Asia) and smaller but strategically important parts (Khevi, Piriketi Khevsureti, etc.) located north of the continent divide (i.e., in Europe). Therefore, Georgia is often described as Eurasian country located on the crossroads of Eastern Europe and West Asia. Georgia is bounded to the west by the Black Sea, to the north and northeast by Russian Federation, to the south by Turkey and Armenia, and to the southeast by Azerbaijan [1].

The Georgian part of the Caucasus started as the Alpine geosyncline in the late Oligocene Epoch, and the region thus reflects the same structural characteristics as the younger mountains of Europe. Therefore, the Greater Caucasus Mountains are mainly composed of Cretaceous and Jurassic rocks with the Paleozoic and Precambrian rocks in the higher regions. Structurally it represents a great anticline uplifted at the margin of the Alpine geosyncline about 25 million years ago and subsequently altered by fresh cycles of erosion and uplift. Hard, crystalline, metamorphosed rocks such as schist and gneisses, as well as pre-Jurassic granites are characteristic of the western part, while softer, Early and Middle Jurassic clayey schist and sandstones characterize the eastern part. The foots of the Greater Caucasus are built of younger limestone, sandstones, and marls. By contrast, the Lesser Caucasus Mountains are formed predominantly of the Paleogene rocks interspersed by the Jurassic and Cretaceous rocks. The youngest geological structures of Georgia are represented by the vast volcanic plateaus in the southern part of country [2‐4].

Two main plain areas – the plains of Colchis and Kura-Aras are also linked to the Alpine geosyncline; the former is related to the formation of the Black Sea, the latter to that of the Caspian. The Colchis plains is mainly represented by deposits broken here and there at the foots of the mountains by the protrusions of slightly older sedimentary rocks. Younger rock also underlies the Kura-Aras Lowland. Overall, three tectonic units can be distinguished by the degree of dislocation of the Earth’s crust: (1) Fold system of the Greater Caucasus; (2) The Transcaucasian intermountain area; (3) The fold system of the Lesser Caucasus. Each of these tectonic units can be further subdivided into finer units [2‐4].

Georgia’s terrain is extremely complex with steep climatic gradients. Four main units of terrain can be distinguished: (1) mountains of the greater Caucasus with peaks over 5000 m (Shkara, Babis Mta, Chanchakhi, etc.); (2) the inter-mountain plains between the Greater and Lesser Caucasus mountains; (3) the mountains of the Lesser Caucasus with peaks rarely exceed 3000 m (Mepistskaro, Kheva, Shavi Klde, Kanis Mta, Arsiani); (4) The Volcanic plateau of the Southern Georgia with elevations from 1300 to 2200 m. These primary units can be further subdivided into secondary ones [2‐4].

Georgia’s climate is determined by its location within a warm temperate zone between the Black and Caspian Seas, and the complexity of its terrain in which mountain ranges and their orientation play an important part. The coastline of Georgia is 330 km long and the climate of the coastal zone is warm: the mean temperature is 4–7 °C in January and 22–23 °C in July. Precipitation is abundant (1500–2000 mm annually), especially in the southern part. At the same time, The Greater Caucasus mountains bars cold air from the north, while warm and moist air from the Black Sea spreads easily into the coastal lowlands from the west till the range of Likhi, which partly impedes further westward movement of the warm and moist air waves. In central Georgia, precipitation in mountains can be twice of that in the plains. Likewise, in the west the warm oceanic-subtropical climate can be found only at lower elevations (less than 650 m); in more elevated terrains and also to the north and east the climate becomes moderately warm. In the mountains weather conditions change to cool and wet quite steeply with increasing elevation and above 2100 m the environment becomes sub-alpine and alpine; permanent snow and ice are found above 3600 m [2‐4].

In the present study we encountered 480 plant species belonging to 249 genera of 95 families being used in the research region (Additional file 1). In Samtshke-Javakheti We encountered 261 useful plant species, of which 160 species were exclusively wild-collected, 81 grown in homegardens, and 20 were both grown in gardens and collected wild. In Svaneti-Racha 203 plant species were used, of which 99 species were exclusively wild-collected, 73 were grown in home-gardens, and 35 were both grown in home-gardens and collected in the wild. The highest number of useful species (317, with 197 species exclusively wild-harvested, 73 were grown in homegardens, and 47 were both grown in gardens and sourced in the wild) was found in Tusheti-Khevsureti.

Plants and their uses showed mostly an overlap in the region, with a slightly wider divergence in uses. Many plant species reported were shared among all regions. However, the geographic locations of Svaneti-Racha and Tusheti-Khevsureti drove greater differences. The highest number of species and of unique species were reported from the remote Tusheti-Khevsureti region (Fig. 2a). A similar distribution was seen in plant uses, albeit with an even greater imbalance of Tusheti-Khevsureti (Fig. 2b).

Elevation of the informant communities significantly fit the ordinations in plant-space (Fig. 3a, r ²  = 0.399, p = 0.001) and in use-space (Fig. 3c, r ²  = 0.119, p = 0.001). Even with the significant overlaps among regions in plant and use inventories mentioned above, region also significantly fit the ordinations for both plant-space (Fig. 3b, r ²  = 0.398, p = 0.001) and use-space (Fig. 3d, r ²  = 0.233, p = 0.001). In contrast, informant gender was not significant in plant-space (Fig. 4a, p = 0.313, r ²  = 0.007) or use-space (Fig. 4b, p = 0.994, r ²  = 0).

Plant species, and uses, found in our study, both for Georgia in general, as well as for its regions, showed clear relations to the wider Mediterranean cultural complex, showing broad overlap with other studies, forming part of what Biscotti and Pieroni [59] described as “hidden Mediterranean diet”. The species number found both in all studied parts of Georgia combined, and in different sub regions, was higher than in most published studies from either the region or the wider Mediterranean and Eurasia region, where numbers of species used ranged from 44 to 330 [60‐82], with the highest figure being the result of a compilation of food plants of the whole of Italy [66]. The figures from Georgia are comparable, because there, although the extension of the study area was somewhat bigger than in some of the cited comparative studies, the number of participants in each village was always very low (sometimes only 1–2), because many villages are depopulated, and the overall number of participants was either similar, or lower in Georgia. Even in close-by Dagestan, just across the Caucasus from the Georgian region of Tusheti, with a very similar cultural background, the use of wild vegetables was much lower (24 species only), although all reported uses coincided [82]. However, the lower number of participants (20, in one village only) in Dagestan might partly explain this divergence, although the field time in Dagestan was much longer, and the number of participants in Tusheti as the closest comparable region in Georgia, was only about twice as high. The much larger incidence of plant use for food in Georgia might stem from the particularly long agricultural and gardening history in the Caucasus. Interestingly, the numbers and uses of medicinal plant species, much more than food plant species, tended to coincide to other studies in the region [62, 83‐91]. Again, given the comparable number of participants, these figures are comparable, although in some cases, e.g. in Turkey, only few villages in each region were surveyed. The one study that found a higher number of medicinal species in a small region in the Catalunya was published by [92]. The authors found 437 species being used.

High UV scores are found in garden rather than in wild-collected species, e.g. Malus domestica, Pyrus communis, Coriandrum sativum, Corylus avellana / C. pontica, Allium victorialis, Vitis vinifera; and garden species also differed much less across environmental gradients than wild-collected species. To some extent, this may reflect the wide geographic distribution of these cultivated species and their cultivated niche, in contrast to wild species with more niche divergence along geographical and topographical gradients. It also underlines the importance of Georgia as an ancient center of crop domestication and diversification and its role in the origin of many domesticated species that are globally spread today.

The use of Rhododendron sp. as agent to clear beer, and as medicinal tea, is rather unique, given the reports of toxicity of the species which extend from ancient Greek and Chinese sources [93, 94] to modern cases of poisoning [95]. In the main center of diversity of the genus, careful use of certain species has been reported for food and medicine [96, 97]. The protection of relatively common species like Rhododendron caucasicum, closely linked to its traditional use, has been shown as essential for alpine treelines often formed by Betula litwinowii [98].

Similaro Rhododendron use, a highly interesting aspect of plant use in Georgia is the use of leaves of many species generally regarded as toxic, e.g. the highly phototoxic Heracleum sp., toxic Conium maculatum Galanthus sp., Lilium sp. and even Solanum tuberosum leaves as food. This indicates a long standing experience with the local wild and cultivated flora, that allows the inhabitants of the region to make best use of all available resources, especially after long winters. Participants indicated that they were aware of the toxicity, and that such plants always needed careful preparation, e.g. long boiling with change of the water various times, and consumption only by mixing with larger quantities of other species, to avoid toxic side effects. In all cases such species were only used in early Spring, when, after a long winter, greens were very scarce. In addition, only young leaves were used. Alternatively, especially in case of Heracleum sp. the plant material was boiled, the water discarded, and the material then pickled with salt and vinegar, to avoid toxicity. The custom to use potentially toxic species seems a result of living conditions in isolated high altitude villages, where fresh food traditionally was scarce, and has, according to most participants, largely been abandoned, with fresh produce becoming more readily available due to better access roads, or simply by moving to the lower plains in winter.

The reported food use of use of acorns of Quercus iberica links Georgian customs to the wider regional food use history, as various species of Quercus have been reported as food from Turkey since prehistoric times [99], Very few data exist on phytochemistry and efficacy of Caucasus endemics. Research on Vaccinium arctostaphylos did however indicate that the species showed some efficacy as antidiabetic [100], while [101] reported on Allium sp. in Georgia.

The process of genetic erosion of ancient crop varieties was originally of little concern for the mountain areas of Georgia, which until the 1990s acted as a repository of ancient crops. Nowadays the main reason for genetic erosion of ancient crop varieties is the demographic decline in mountain regions due to harsh economic conditions and lack of modern infrastructure [1, 23, 102‐106]. The shift from ancient cultivars to modern high-yielding crops such as maize and potato, which took place in the lowland areas much earlier, began in mountain villages after the end of Soviet occupation, when local inhabitants who had been forced to the lowlands returned to their original villages. Similar changes have been reported from other former Soviet republics [106]. In addition, the rehabitation of high altitude villages has been only partial – while some families have returned at least for the summer, many villages remain in ruins. In occupied villages old household utensils like butter barrels are often to be found in storage, but not used anymore. Small bridges are still made from wood, but many other wooden household items like beautiful bed-headboards are simply discarded. Some implements, e.g. snowshoes or brooms are still maintained. Agricultural tools such as hay rakes are a common sight in abandoned barns, but more sought afar items like ox-drawn threshing sledges could only be found in museums [1]. While sheep were produced on a large scale during Soviet times, leading to widespread overgrazing, nowadays only a few scattered herds remain, and traditional wool items are getting more difficult to find, while tourist products abound along roadsides especially in the outskirts of Tbilisi and resort areas like Borjomi and Barisako. Sadly, we could only find some cultivation of Hordeum in Svaneti, although many participants mentioned that old landraces of wheat and barley were formerly preferred to prepare bread and beer for religious rituals. All over Georgia abandoned terraces indicate where grain was formerly grown. Many old barns still contain clay lined grain storage baskets made from Salix sp., which quite often contain old grains. However, essentially no grain has been grown in the surveyed high altitude regions of Georgia for decades, according to all participants recalling grain cultivation at all. One old storage chest in an abandoned barn was still half full of oats, probably harvested in the 1970s, and some wheat bran was still found in an abandoned house. Now villagers buy wheat to distil alcohol or to bake bread, or buy commercial beer making mixtures to brew their own beer [1].

The National Botanical Garden in Tbilisi runs a large seed bank and in-situ growing program for rare local species and varieties of Triticum, Panicum, and Sorghum, and some material is grown at the Ethnographic Museum in Tbilisi, where Sorghum is grown and dried and gruel with Prunus sauce is available to visitors, and conservation efforts to preserve endangered medicinal plant species have been started during the last decade [102].

The maintenance of home gardens in Georgia serves as socio-ecological memory, like in other regions [107, 108], and as such is an irreplaceable tool to maintain Georgian culture. In contrast to other regions, this represents not just a reflectance of growing popularity of gardening and gathering [109, 110], but cultural survival. While the great variety of plant species used in the Georgian Caucasus might provide a reservoir for food security, similar to the Balkans [110], climate change is starting to affect both natural floristic diversity and gardens both in the Caucasus as well as continent wide [111, 112].