Unity in diversity—food plants and fungi of Sakartvelo (Republic of Georgia), Caucasus

The Caucasus is regarded as global biodiversity hotspot [5‐8]. Botanical has a long history, and the vegetation composition as well as flora are well-known [2, 3].

The territory of modern-day Georgia (Fig. 1) has been inhabited since the early Stone Age, and agriculture was already well-developed during the early Neolithic [9], although human occupation started already in the Early Pleistocene, with the 1.7-Myr-old hominid fossils of Dmanisi in Southern Georgia being the earliest known hominid-site outside of Africa [10‐12]. The history of plant and animal use has been documented since the Upper Paleolithic through fossils found in Dzudzuana Cave, dated to ~ 36–34 Ka BP, including wool (Capra caucasica), and dyed fibers of wild flax (Linum usitatissimum) [13]. Archeological findings from the Neolithic and Early Bronze periods dating back to the 6th–2nd millennium BC are rich with plant fossils and seeds of both wild species and local landraces [14]. The earliest seeds of Vitis vinifera (grapevine) were excavated in southern Georgia and date to about 8000 years BP [15]. Medicinal species like Alchemilla millefolium, Artemisia annua, A. absinthium, Centaurea jacea and Urtica dioica found in the archeological record are still used in the modern pharmacopoeia [16].

Due to its ancient roots agriculture in Georgia is characterized by a great diversity of landraces, and endemic species of crops, already documented in Soviet times [17‐22]. However, starting with the implementation of Stalinist agricultural reforms in the 1950s, a rapid loss of local cultivars occurred [23‐26]. This process accelerated during post-independence, and knowledge loss has been shown to even extent to aggravate wolf-human conflicts [27]. However, a wide variety of local cultivars can still be found in case of Vitis vinifera (Vitaceae) shows its highest genetic diversity in Georgia, with over 600 varieties known, and several dozen used commercially [9, 15, 28‐31]. In contrast, essentially none of the 144 varieties, and 150 forms of wheat (Triticum) registered in Georgia in the 1940s [21, 22] are sown in modern Georgian commercial agriculture [25], although traditional varieties are still reported from nearby Turkey [32]. The situation is similar in case of Hordeum vulgare (Poaceae) which originally was important in beer production, for religious rituals and traditional medicine [9, 33] and Secale cereale (Poaceae) [34].

In contrast to the loss of cereals, legumes like peas (Pisum sativum), lentils (Lens cornicularis), chickpeas (Cicer arietinum), fava beans (Vicia faba), and vegetables like garden lettuce (Lactuca sativa), beans (Phaseolus vulgaris), basil (Ocimum basilicum), peppermint (Mentha x piperita), onions (Allium cepa), sugar beets (Beta vulgaris), spinach (Spinacia oleracea), carrots (Daucus carota), radishes (Raphanus sativus), turnips (Brassica rapa var. rapa), welsh onion (Allium fistulosum), amaranth (Amaranthus viridis), goosefoot (Chenopodium album), leeks (Allium ampeloprasum) and garlic (Allium sativum) are still common in home gardens. Herbs like parsley (Petroselinum crispum), coriander (Coriandrum sativum), tarragon (Artemisia dracunculus), savory (Satureja hortensis), garden cress (Lepidium sativum), dill (Anethum graveolens), fennel (Foeniculum vulgare), celery (Apium dulce), and Allium fistulosum (Chinese onion are widely cultivated and popular ingredients of local cuisine [1]. The maintenance of such diversity is of high importance as source material for global crop production [35, 36]. Many species are widely sold as medicines [37].

Over the last years, ethnobotanical research in Georgia has received a large boost, and a wide variety of studies on all aspects of plant use have been published [38‐52]. Few of these however focused entirely of food plants [38, 52], many of which are still cultivated in small home-gardens. Home-gardens are often cited as important reservoirs for crop germplasm [53‐58] and are mostly sources of food [59, 60]. In wider Eurasia, home gardens have been shown to be an important repository of plant diversity are often part of complex seed exchange networks [61‐64].

Given the trajectory of ethnobotanical studies in Georgia, a meta-analysis of the data food plant uses was long overdue. In this publication, we hypothesized that (1) given the long tradition of plant use, and the isolation under Soviet rule, plant use both based on home gardens and wild harvesting would be more pronounced in Georgia than in the wider region, (2) food plant use knowledge would be widely and equally spread in most of Georgia, (3) there would still be incidence of knowledge loss despite wide plant use, especially in climatically favored agricultural regions in Western and Eastern Georgia.

From 2013 to 2019, we interviewed over 380 participants in all regions of Georgia not occupied by Russian forces on their general plant use, recording over 32,000 individual uses. The analyses of all uses have been published in a variety of papers [41‐50]. However, of all uses over 19,800 mentions were of food plants, which is why we regarded it as prudent to present a separate analysis of these. Interviews using semi-structured questionnaires were conducted after obtaining the oral prior informed consent of the participants, which were selected by snowball sampling, trying to reach gender balance and representing different age groups. Most participants were however over 50 years old, as interviews targeted remote villages where only very few younger people remain. All interviews were carried out in the participants’ homes and gardens by native speakers of Georgian and its dialects (Imeretian, Rachian, Lechkhumian, Tush, Khevsurian, Psavian, Kakhetian), other Kartvelian languages (Megrelian, Svan) and minority languages (Ossetian, Ude, Azeri, Armenian, Greek). The languages in which a plant was mentioned are indicated in Table 1. Interviews were subsequently translated into English. Plants grown in home gardens were used as prompts, while wild-collected species were free listed. We classified species as "garden" when they were grown/collected in cultivated areas, and as "forest/wild-collected" when growing and harvested in the wild. We maintained the distinction of "forest" and "garden" because it was used in our previous publications from the region [50], to maintain consistency. In contrast to many other countries Georgia benefits from a complete flora [65‐69] and a broad inventory of vernacular names in all languages [68]. Species were identified directly in the field, using this literature, and vouchers collected and deposited in the National Herbarium of Georgia (TBI). The nomenclature of all species follows www.​tropicos.​org, under APGIII [70]. Collection permits were provided through the Institute of Botany, Ilia State University, Tbilisi.

Data were tabulated using excel sheets and a combined matrix was constructed with plant entries in rows and plant data in columns including date, place, participant’s age and gender, interviewer, plant identity (Latin, Georgian vernacular, local names), the use category, which parts were used, and the source (garden or forest). We compared species diversity among groups of species (forest versus garden, various provinces) using sample-based rarefaction as well as widely used diversity indices: Dominance (D), Shannon (H), Evenness (e^H/S), Simpson index, (1 − D), Equitability (J), Fisher alpha, Berger–Parker (BP), given that no single index may sufficiently show the importance of certain species. Similarity of species composition among groups of plants were analyzed using non-metric multidimensional scaling (nMDS). All these analyses were performed using software PAST4.02 [71].

Test if the usage of plants based on family and genus, plant system used, and general and specific plant parts differ between regions and different altitudinal ranges. I predict that these components will be different, since there will be a different plant composition among regions and along an altitudinal gradient, and that different human communities have their own ethnobotany knowledge, even though they are from the same country.

We compared the usage of plants based on their (i) family and (ii) genus, (iii) system (root, shoot, or both), and (iv) general (vegetative, reproductive, or both) and (v) more specific (bark, branches, buds, bulb, cones, flowers, fruit, latex, leaves, resin, roots, seeds, shoots, silk, stem, timber, tuber, whole plant) parts used between regions and altitudinal ranges. We also compared (vi) for what purpose plants are used between regions and altitudinal ranges. We removed from our analyses any data that was not possible to make any further identification, such as plants identification above family, and uncertain plant parts. We also removed fungi from our analyses, and samples in which we had no more details about the purpose of usage of plants, i.e., in cases where plants were used as human food, but we did not know exactly for which kind of food. We considered regions and five altitudinal ranges (0–500 m, 501–1000 m, 1001–1500 m, 1501–2000 m, 2001–2500 m) as factors within our ordinations. We conducted non-metric multidimensional scaling (NMDS) followed by a permutational multivariate analysis of variance (PERMANOVA) with Euclidean distance and 999 permutations using the “RVAideMemoire” package [72].

Of all food preparations the use of plants as ingredient of boiled herb preparations (mostly as —gazapkhuli pkhali = Spring Pkhkali, as the first vitamin source after winter), and as lacto-fermented or vinegar-based pickles are probably the most emblematic ones in the Caucasus, given that almost 50% of all food mentions were for phkhali, and almost 12% for pickled plants, and 8% for teas.

While the overall distribution of families, genera and their uses were similar between regions, overall most species were used in Guria. However, the knowledge distribution was most uneven for these food categories (Fig. 7). The altitudinal range between 1001 and 1500 m, followed by 1501–2000 m were clearly predominant when it came to diversity of plants used as well as uses (Fig. 8). This very unequal distribution of the most important families/genera, as well as their respective uses is reflected in Fig. 9. The altitudinal differences do not necessarily indicate however that the respective species did not grow also at lower altitudes. They simply indicate that at lower altitudes the participants rather preferred other food plants, and due to a lack of necessity were not interested in wild harvesting greens.

Only 60% of participants reported making pickles / lactofermented preparations. Of these, over 16% each came from Zemo Imereti and Khevsureti, and 12% each from Zvemo Svaneti, the Javakheti-Plateau, and Guria. The first regions represent all high altitude—short growing season areas, where the population does need to preserve food for winter. Guria is relatively warm—but very wet and snow-rich, which also might explain the prevalence of pickles. No participants whatsoever from Adjara, Samegrelo (the most subtropical regions) and Mtianeti (close to the capital Tbilisi) reported making pickles. Unsurprising, Kakhetians were also not enthusiastic about this form of preparation, because Kahketi is also a region famous for its large agricultural production. In contrast, in Tori and Tusheti there are simply less products that can be pickled. Preferred species (of a total of 79) for pickles were mostly Amaranthaceae (Amaranthus, Chenopdium), Apiaceae (especially the stems of Anthriscus, Chaerophyllum and Heracleum were pickled, but also, stems of Conium maculatum), Amaryllidaceae (all Allium species), and Polygonaceae (Polygonum and Rumex). In addition, Aruncus vulgaris (Rosaceae), Stapyllea colchica (Staphyleaceae). All of these were more important as pickles than "traditional European style species (Cucumis sativus, Capsicum etc.). The fermentation of the ferns Mattheucia struthiopteris (Onocleaceae) and Dryopteris filix-mas (Dryopteridaceae) was similar to what we observed, e.g., in the Himalayas.

The participants clearly indicated that some plants (e.g., Conium maculatum, Dryopteris filix-mas, Galanthus sp., Narcissus sp.) needed careful preparations, due to possible toxicity. However, given that these species might have even higher toxicity in other regions, e.g., Central Europe, the authors decided to not elaborate any further on preparation methods, given that these might not be sufficient to remediate toxicity of the same species outside the Caucasus.

In case of Pkhali, over 93% of all participants—from all regions—reported to use such boiled herbs, normally in Spring. This was surprising, as we had expected much more limited use in the climatically favorable regions. Nevertheless, Zemo Imereti (19% of all Phkhali preparations), Tori and Kvemo Racha (16% each), Tusheti (15%) and Khevsureti (14%)—all mountain regions with long winters, stood out as the real "herb eater" areas. In contrast to the pickled species, essentially only young leaves were used for pkhali, with great emphasis on the same families indicated in pickles. (All pickled plant species were also used for phkhali.) The overall number of species fused or pkhali was however much higher (197). The elaboration of phkhali often involves many steps to reduce the toxicity of species used, and in most cases a wide variety of herbs are included in each preparation. Interesting examples for the use of toxic species included the leaves of Solanum tuberosum, Veratrum lobelianum and Viola sp. Solanum tuberosum leaves for example are regarded as toxic worldwide, but are being eaten in the Caucasus and Albania [48]. Veratrum album (closely related to Veratrum lobelianum, and growing especially in Europe, is highly toxic), and Viola sp. (although especially the flowers are widely used in gastronomy) contains toxic Saponins. In all cases careful preparation was mentioned to make these species palatable. The authors explicitly decided to not give any recipes, given that many of the species are widespread, and compound composition—and with it possible toxic effects—might vary across the distribution range, so that a preparation method that sufficiently reduces toxicity in the Caucasus might not necessary be applicable in other areas.