Medicinal plants in the cultural landscape of a Mapuche-Tehuelche community in arid Argentine Patagonia: an eco-sensorial approach

Nahuelpan is situated in the north west of Chubut province, Patagonia, Argentina (43° S, 71° W) (Figure 1). The general climatic characteristics are strong winds and frosts all year round, snow in winter and a dry season in summer. The average annual temperature is 8°C, with precipitation of approximately 400mm annually. Phytogeographically, this area is included in the occidental Patagonian district, Patagonia province [22]. The dominant vegetation is typical grass-bush steppe, with an abundance of graminaceous Poa spp., Pappostipa spp. and Festuca spp., subshrubs of Mulinum spinosum Cav. (Pers.), bushes of Nassauvia glomerulosa (Lag. ex Lindl.) D. Don, N. axillaris (Lag. ex Lindl.) D. Don, Berberis microphylla G. Forst., Adesmia volckmannii Phil., Nardophyllum bryoides (Lam.) Cabrera, Azorella monantha Clos, Senecio filaginoides DC., and in some sectors Corynabutilon bicolor (Phil. ex K. Schum.) and Schinus roigii Ruiz Leal & Cabrera. Among the herbaceous plants the most notable are Cerastium arvense L., Oenothera odorata Jack., Arjona tuberosa Cav., Euphorbia collina Phil., Plantago lanceolada L., Acaena pinnatifida Ruiz & Pav., Calceolaria sp., Rumex acetosella L., among other plants. In areas close to “mallines” (wetlands of glacial origin) the woody plants Discaria spp., Schinus patagonicus (Phil.) I.M. Johnst. ex Cabrera and Baccharis obovata Hook. & Arn. grow, as well as the herbaceous Mutisia retrorsa Cav. and Taraxacum officinale G. Weber ex F.H. Wigg., among others. In the highest areas with southern exposure, or in the wet gullies, stunted Nothofagus pumilio (Poepp. & Endl.) Krasser forests grow [22].

The Nahuelpan community is composed of 60 people, living in 21 homes. Land ownership is communal, under the category ‘indigenous reserve’, with the exception of two families who have a title deed to their properties. The area of indigenous reserve is 7500 hectares [23]. This population comes under the jurisdiction of the municipal government of Esquel (43900 inhabitants, town center 15km distant), department Futaleufú. Most inhabitants are Mapuches, and some are Tehuelches. The Mapuche native language is Mapuzungun (‘language of the land’), of the Nahuelpan linguistic tribe, but at present only 6% of the population are active speakers, and they are elderly and bilingual [23]. There are no speakers of the native Tehuelche language.

The principal economic activity is livestock raising, on a large scale, with sheep and goats bred for wool and meat production. The products originating from this activity satisfy only basic subsistence requirements.

The main public institution is the primary school, where cultural events take place such as workshops teaching the Mapuche language, veterinary medicine, vegetable gardening, spinning, wool dyeing and knitting, generally organized by extension organizations such as the National Institute of Farming Technology (INTA: Instituto Nacional de Tecnología Agropecuaria) or the Social Farming Program (PSA: Programa Social Agropecuario). Funeral wakes are also held in the school buildings, which function as a community center.

Most of the population dwells close to the school and train station, where the craft shop and a small museum dedicated to the history and indigenous culture of Patagonia are also situated. The remaining dwellings are located between one and fifteen kilometers from this center.

Inhabitants usually move around between houses, or go to the school or Esquel on horseback, on foot or by hitching a lift, since few own a vehicle. There is no public transport in the area. Nevertheless, very frequent visits are made to Esquel since most families have relatives living in this city.

The local medical system can be identified as Creole [24], since therapeutic criteria pertaining to the Mapuche culture [25], coexist with European elements, Christian symbolism, magic practices and the official medicine. The community has no health clinic, but a health worker who resides in the community visits the homes periodically and constitutes a link with the regional hospital in Esquel.

The absence of alternative work, the scarcity of land, which limits the size of the herds, and the lack of water, which restricts the development of agriculture, among other socio economic factors, converge and lead to an accelerated process of migration of the youngest community members, who move mainly to the cities of Esquel, Trelew (607 km) and Comodoro Rivadavia (595 km). Consequently, there are an elevated proportion of adults and elderly in the population.

Fieldwork was carried out within the framework of the principles established by the United Nations 1992 Rio de Janeiro Convention on Biological Diversity for the regulation of access to genetic resources and associated knowledge, protection of traditional knowledge and recognition of rights to intellectual property [26]. Authorization for this study was requested from local officials (tribal chief, health worker and headmistress of local school). In addition, informed consent was requested from each interviewee.

Information relating to the cultural landscape experienced by each informant in terms of medicinal plants, knowledge of species and their organoleptic perception was obtained through participant observation, free listing and semi-structured and in-depth interviews, considering that the concept of perception is equivalent to representation, as the externalization of what an individual perceives through all physiological pathways (biological, psychological and cultural senses) [27].

Sampling method consisted of a census of all households in the community. A family of each house was invited to participate in the study. Eighteen families agreed to participate, and one member of each family offered to be interviewed voluntarily. In total, 14 permanent inhabitants and 4 semi-permanent (individuals who live part of the week in Esquel) were interviewed, all representing 85% of the families.

We use a free listed technique for studied the richness of known and used medicinal species, and its Creole and Mapuzungun names. Through interviews we inquire the methods of preparation and administration of each species, procurement strategies (collection, cultivation, purchase and/or barter), and gathering environments. In the depth analysis of the discourses we approach to the importance of the general chemo-sensorial (aroma and taste) perception involved in the recognition, selection and use of medicinal plants, as well as other items of general interest.

In addition, walks with and without informants were carried out, during which reference material was collected which was placed in the BCR herbarium of the Universidad Nacional del Comahue. The botanical nomenclature used follows Zuloaga et al. [28]. The Mapuzungun nomenclature used follows Díaz Fernández [23].

Analysis was quali-quantitative, following different methods used in the study of environmental perception to assess worldviews, sensations, values and opinions [27].

The nomenclature and biogeographical origin (native or exotic to Patagonia) of the medicinal species was checked by consulting Zuloaga et al. [28]. Total species richness and richness of botanical families was estimated using the total sum of species and families respectively. Use consensus for each species was calculated with the formula: number of informants who cited each species/total number of informants (N = 18) x 100 [8].

Using qualitative discourse analysis [27], opinions given by the informants regarding the intensity, characteristics and quality of the plant organoleptic sensations recognized were analyzed, and in particular, the significance of the plants and of their sensorial attributes as expressed in Mapuzungun. Following this, the perceptions of aroma and taste were classified according to the informants’ (emic) criteria.

The consensus on organoleptic characteristics (OC) was also estimated using their relative frequencies (total number of mentions of the organoleptic characteristic under consideration for the species i x 100/total number of informants who cite the species i) [29].

Following this, the medicinal uses were grouped in etic categories in order to enable quantitative comparisons to be made [25]: gastro-intestinal (GI), respiratory (RE), analgesic-anti-inflammatory (AAI), dermatological-cosmetic (DC), cultural syndromes (CUS), fever (F), cardio-vascular (CV), obstetric-gynaecological (OG), genito-urinary (GU), and other uses (endocrine, ophthalmic, etc.) (O). The numbers registered were compared between categories with the Chi squared test (p <0.05).

The plant landscape units which provide medicinal plants were characterized according to informants’ precepts [27]. Aromatic and sapid species richness was compared with the richness of non aromatic and non sapid species for each unit, using the binomial test (p <0.05).

In order to compare the cultural importance of the different plant landscape units, the relative importance (RI) of each species was calculated per unit [30], using the following formula: RI = NBS + NP, where NBS is the number of body systems treated by a particular species (NBSS) divided by the number of body systems treated by the most versatile species (NBSVS); NP is the relation between the number of medicinal properties attributed to a given species (NPS) divided by the total number of properties attributed to the most versatile species (NPVS). Following this, in order to obtain weighted frequencies, the RI values were multiplied by the consensus of each species. The maximum value of this index is 200. The values thus obtained were compared between different landscape units with the Kruskal-Wallis test [8].

The Nahuelpan herb landscape is heterogeneous and includes areas which have been transformed to some extent, presenting different levels and types of relationship between inhabitants and the physical and natural components. In this landscape most medicinal plants are acquired by collection (78% of cites), and to a lesser extent by cultivation and harvesting (9%), and purchase or barter (13%) (p <0.05) (Table 1).

Gathering in particular is carried out in areas where the successional management of fodder plants and shrubs is considered a priority. This practice increases the frequency of visits to the different herbal landscape units, enabling verification of the presence of resources and changes in their availability, as well as the perception of their colors, flavors and aromas. Plants resources are collected in quantities suitable for family use alone, principally in zones close to water bodies, which include rivers and waterholes known as “menucos” or “aguadas”, and flood meadows or “mallines” of glacial origin (23%). On some family lands, other management practices have been observed, such as the diversion and/or isolation of these water bodies for the protection of medicinal, edible or fodder species of high cultural value. The importance of these peri-aquatic environments as sources of medicinal resources is likely to be a result of their high levels of biodiversity [31], a characteristic valued by local populations [32].

To a lesser extent, gathering is also carried out on the meseta and plains, known as “pampas” and “lomas secas” (21.5%) where the stock animals are grazed for most of the year; and on the stony slopes “pedreros de la cordillera” and “nevados” (a high Andean phytogeographic environment) (18%). This last mentioned region is visited by inhabitants who still maintain the practice of summer sheep and goat pasturing (around 50% of family heads). Various studies have reported that this summer pasturing constitutes a form of management that allows pastures to rest, and implies successional herb management, which favors more efficient use of weeds spread by the animals [18].

Another environment worthy of note is the area surrounding the dwellings, described in the interviews as “just around here”, and other anthropized sites such as the verges of main roads and country roads, paddocks and corrals (16%). Taking advantage of these readily available and easily accessible ruderal species [19, 33] implies a kind of management, due to the link between their dispersion and human activities. Particularly, in this environment, an interesting case is the use of Schinopsis lorentzii (Griseb.) Engl. (red quebracho). This species is native to the Chaco region of NE Argentina, and is sold in health food shops and pharmacies in Argentina due to its well-known anti-diarrhoea, emollient, antiseptic and tissue healing powers [34]. Nevertheless, in Nahuelpan this species is obtained mainly by gathering, in this case by the scraping of fence posts or railway track sleepers made of this wood. Thus, the inhabitants take advantage of the cultural landscape in multiple, original ways, according to local availability.

With regard to the eco-sensoriality of these herbal landscape units, it was found that apart from in the “pampas” and “lomas secas”, most medicinal plants belonging to remaining environments are basically defined, characterized and valued according to their taste (binomial test, p <0.05). In contrast, with respect to their aromaticity, only in the “pedreros” and “nevados de la cordillera” did aroma figure as a differential trait in most of the plants (binomial test, p <0.05).

However, these units are not isolated and present a certain amount of spatial continuity, not only with respect to ecological gradient but also to the many interconnections generated from the network of roads and tracks established and used by the inhabitants themselves and their domestic animals. Because of this, their limits are not clear-cut, but rather diffuse and porous [7]. According to ethnobotanical approach the physical spaces of cultural landscape are scenarios that reflect an intricate network of people, places and resources over time, so that their boundaries are necessarily dynamic in response to different needs, ideas and cultural practices [2]. In particular, these paths often guide the movements of the shepherds and their flocks, having been tread and re-tread in response to the differential availability of pastures in different years, and the establishment or abandonment of dwellings. These interconnectors themselves favor the exchange of medicinal plants among neighbors, as well as activities associated with other products such as sheep’s fleece, tools, food, etc.

The social and economic activity of bartering fulfills an important role in the recreation of the Nahuelpan plant landscape. This practice favors the periodic interaction of families within the community and with others from neighboring communities, or rather, with workers who return from the sheep shearing operations on other Patagonian ranches.

By means of barter, other species from distant environments, which are mostly aromatic and sapid, are added to the repertory of plants used (binomial test, p <0.05; Table 1). Among these, worthy of special mention are Larrea sp. (“jarilla”) native to the Patagonian Monte, Solanum crispum Ruiz et Pav.(“natre”) native to sub Antarctic forests, and Eucalyptus sp. (“eucalito”), an exotic species native to Australia, planted widely along the Atlantic coast that is commonly gather by rural workers in the ranches.

Bartering is complemented with purchasing, an additional strategy which allows the acquisition of fragmented, packaged or loose medicinal resources in grocer’s, health food shops and pharmacies in the town of Esquel, or from travelling salespeople. Some authors suppose that this practice could indicate disuse of gathering, or even processes of erosion of traditional knowledge [35]. However, in this case study, purchase as a supply strategy indicates processes leading to the expansion and/or diversification of the therapeutic cultural landscape [6]. In this sense, the incorporation of resources exogenous to Nahuelpan could be associated with an adaptive strategy to deal with a serious environmental circumstance, such as the growing regional process of desertification which limits the availability of some of the repertory of plants the people need (e.g. Matricaria recutita L. and Gunnera tinctorea (Molina) Mirb.).

The herbal landscape also includes the homegardens constructed by inhabitants, modifying the appearance of the location, and constituting food and medicinal plant supply sites. These plant sources are frequently situated in peridomestic areas. Using this strategy, fourteen species of exotic medicinal species (e.g. Melissa officinalis L., Mentha spp., Beta vulgaris L., Salvia officinalis L. and Tanacetum balsamita L.) are harvested, which is a low number for the inhabitants, and a consequence of a lack of irrigation water, although the progressive loss of ancestral domestic horticultural practices could also be a cause [20]. The majority of these plants are for alimentary use, and originated from packet seed provided by INTA.

In these cultivation sites preexisting native species in the homegardens are tolerated and/or protected, coexisting with the cultivated ones, as is the case of the shrubs Corynabutilon bicolor (Phil. ex K. Schum.) Kearney and Fabiana imbricata Ruiz et Pav., which are also valued as hedges, for protection and shelter from the wind and sun, and refuge for farm animals. Following [5, 36], tolerance is a common management practice here so which these plants are left deliberately standing when vegetation is disturbed; in addition, people make actions of protection favoring permanence of these plants through special care (pruning, elimination of weeds, etc). However, no evidence was found in homegardens of other management practices with this native medicinal plants, such as transplanting or planting seed or propagules from wild areas.

Other species such as Populus spp., Sambucus nigra L., Tanacetum vulgare L. and Iris spp., are cultivated principally for their ornamental value and as shelter from the wind, and occasionally used for medicinal purposes (Table 1). The fact that these are multifunctional species seems to be a very important selection criterion in rural communities. It has been found that in hedge species, their additional alimentary and/or medicinal value constitutes a notable trait in rural populations of Patagonia [37, 38]. However, there are also other medicinal species used which are important due to their uniqueness and effectiveness, such as Salvia officinalis L. for obstetric-gynaecological diseases and Mentha aquatica L. for gastro-intestinal pains.

Three exotic species are cultivated in pots: Sedum telephium L., Ruta chalepensis L. (both outdoors) and Aloe sp. (indoors), which are, in general, plants valued for their therapeutic and symbolic prestige, whose use extends to other Mapuche communities in the region [25]. These are plants which also adorn dwellings, but their principal symbolic function is to act as protectors or defensive elements and purifiers of the domestic environment. The cultivated species are mostly cited with reference to their sapid qualities (binomial test, p <0.05), while aromaticity is not a feature that characterizes them significantly (binomial test, p >0.05).

The highest average values for cultural importance were obtained for the species found in high environments, on the stony slopes or “pedreros de la cordillera” (average consensus value * RI = 29) followed by the water bodies: “arroyos”, “menucos” and “mallines” (25), while the lowest values were obtained for the units close to dwellings and other anthropized zones (20), for the dry plates: “pampas” and “lomas secas” (11), for “purchase” and “barter” (10) and for the cultivated areas (9). However, the comparative analysis of these values indicates no significant differences (Kruskal-Wallis test, p = 0.65). One relevant characteristic of the principal species, in terms of the indices considered, whether gathered, purchased, bartered or cultivated, is that they are aromatic and/or sapid (Table 1).

The higher cultural importance of species coming from high Andean environments coincides with reports on other Andean populations in the southern cone [33, 39]. This speaks of the great therapeutic versatility of these environments, which could explain their high cultural value. Molares and Ladio [25] have highlighted the sacred character and the higher medicinal potential of the highest altitude levels for other Mapuche communities of Argentina.

Nahuelpan inhabitants mentioned 121 ethnospecies belonging to 55 botanical families, of which 108 were identified taxonomically (Table 1). The most frequently cited species were: Baccharis sagittalis (Less.) DC (“carqueja”) (83.3%), Gunnera tinctorea (Molina) Mirb. (“nalca”) (83%), Artemisia absinthium L. (“ajenco”) (72%), Fabiana imbricata Ruiz. & Pav. (“palo piche”) (72.2%), Adesmia boronioides Hook. f. (“paramela”) (66.7%), Marrubium vulgare L. (“malva rubia”) (55%) and Valeriana carnosa Sm. (“ñamkulawen”) (66.7%); all these species are strongly aromatic and/or sapid.

Considering only the data on the taxonomically identified species, it was found that native species richness (59) was higher than that of exotic species (49) (binomial test, p <0.05). In recent years the use of exotic species has begun to be interpreted as possibly reflecting a certain amount of flexibility on the part of individuals in order to take advantage of the changes taking place in their cultural landscape, as they incorporate new resources that contribute to their survival and wellbeing. This would indicate exploratory processes with unknown or recently discovered plants, demonstrating a certain capacity for adaptation on the part of local inhabitants [40].

Of the inhabitants interviewed, 80% mentioned that all the medicinal plants had an aroma, and that if an aromatic plant was not recognized as medicinal it was very likely that it hadn’t been tested to identify its properties.

Of a total of 456 positive recordings of the presence of organoleptic characteristics of the mentioned species, it was found that 60% corresponded to flavor and 40% to aroma. There are no organoleptic data for 34% of the species registered. This could be due to the taboo associated with communicating certain symbolic aspects of traditional botanical knowledge to people from outside the community, in particular because certain strong aromas serve as vehicles or intermediaries between the natural and supernatural worlds [29].

Of the plants cited, 78 species are described by their flavor and 52 by their aroma (Table 1). In general terms informants classified the flavor as “acid”/“sour” (e.g., the whole plant of Oxalis spp.), “bitter” (e.g., the stalks of Baccharis sagittalis (Less.) DC), “spicy” (e.g., the roots of Lycium chilense Miers ex Bertero), “sweet” (e.g., the branches of Ribes cucullatum Hook. & Arn.), and “dry”/“like alum”/“like tea” (referring to Camellia sinensis, e.g., the roots of Acaena splendens Hook. & Arn.) (Table 1). The last mentioned character refers to the perception of astringency, which, according to Amat and Vincent [41] is a property perceived more by the sense of touch than of taste.

Aroma is perceived as “scented” (e.g. branches of Acantholippia seriphioides (A. Gray) Moldenke), “minty” (referring to Mentha spp., e.g. branches of Clinopodium darwinii (Benth.) Kuntze), “like boldo” (referring to Peumus boldus Molina, e.g. branches of Dysphania ambrosioides (L.) Mosyakin & Clemants), “like tobacco” (referring to Nicotiana tabacum L., e.g. leaves of Verbascum thapsus L.), “like the smell of dirty feet” (e.g. roots and rhizomes of Valeriana carnosa Sm.), “heavy, dense” (e.g. branches of Ruta chalepensis L.), “like caramel”, because of the aroma and resinous texture (e.g.: stalks of Adesmia boronioides Hook. f.).

In addition, in many cases aroma and flavor were interpreted together, and subclassified into two contrasting categories: “füre” (strong/unpleasant/disgusting, in Mapuzungun) (e.g. branches of Artemisia absinthium L.) and “mild/nice” (e.g. roots of Armeria maritima (Mill.) Willd.). In the interviews, informants were not able to distinguish between unpleasant and strong, or between mild and nice. This indistiction between the quality and the intensity of aromas and flavors may indicate the absence of linguistic labels for these perceptions [42], or possibly a fundamentally practical perceptual-functional connection.

It is noteworthy that certain species with mild aromas and/or flavors, recognized as “kochü lawen”, are used for strongly culturally based syndromes. For example, Erodium cicutarium (L.) L’Hér. ex Aiton, a plant which has become established in the wild and is widespread in anthropized areas throughout the region, is used to treat the “pasmo”, a condition that includes symptoms such as stomach pains, cramps and abnormal pigmentation of the skin, which is caused by an imbalance between the states of hot and cold; the cultivated, aromatic Melissa officinalis L. is used for “afligimiento del corazón (heart troubles)” which involves feeling sadness and a general decline in spirits; the purchased seeds of Linum usitatissimum L.are used after childbirth (for “domo kütran” or “mollfüñ kütran”) which is “cuando la sangre queda coajada adentro (when coagulated blood remains inside)”, a problem which presents symptoms of headaches, backaches and bleeding after the birth, and can be fatal. There are also certain problems related to the supernatural world, such as the “susto” (fright), the result of a meeting with spirits such as the “anchimallen” (who takes the form of a child), with the “cherrufes” (lights in the countryside), with the “meulen” (dangerous whirlwinds), or with the “cuero” or “wayllepen” (an animal with extended limbs which appears in isolated places close to water bodies), among others, which often require highly aromatic species in their treatment. These belong to the group of the “alwe lawen” (medicines for the souls of the dead), and include species such as Rosmarinus officinalis L., Ruta spp., Laurus nobilis L. and Artemisia absinthium L., which are considered “füre lawen” (strong, bitter, potent medicines). These species are generally used in the form of aromatic smoke, thrown on the embers of the fire; hung on the body as amulets beneath the clothing, on the walls of dwellings, or on the door thresholds as protectors or ‘defensive’ elements. They also tend to be grown in pots or in homegardens so as to favor the wellbeing of the family and their animals.

In order to deal with these and many other problematic situations, the informants have restructured the significance of resources which have appeared relatively recently in the region. These processes show, in part, the adaptive capacity of these indigenous communities, which comes into action when socio-cultural and ecological changes must be faced [18].

Similar to that detected in the studies carried out in communities of the sub Antarctic forest [8, 25], it was found that the plants with highest use consensus, in this case used for digestive, respiratory, cardio-vascular, analgesic-anti-inflammatory, obstetric-gynaecological and genito-unrinary complaints, have the highest frequencies of cites reporting flavor (Spearman test, p <0.05), and those with the highest frequencies relating to digestive, analgesic-anti-inflammatory and cultural syndromes present the highest frequencies of cites reporting aroma (Spearman test, p <0.05; Table 1).