Introduction

Ethnomedicine is defined as the cultural interpretation of health, disease and illness; it is a complex and multidisciplinary system constituting the use of natural resources for healing. Many people still depend on plants as alternative remedies in addition to biomedicine. The extent of traditional medicine usage differs with the geographical location and availability of the resources. India has rich biological diversity and possesses almost 7% of the World's flowering plants. The Western Ghats of India are blessed with high biological diversity and various ethnic groups. The ethnobotany of the Western Ghats in Tamil Nadu has been explored previously by some researchers; there are still some places to be covered. According to 2011 census, the tribal population of Tamil Nadu state in India was estimated as 0.72 million; it constituted 1.1% of the total Tamil Nadu population. There are about 36 tribal groups in Tamil Nadu, mostly dwelling in the fringes of the Western and Eastern Ghats. Virudhunagar district had 2,294 tribal people, which was 0.12% of the total population of the district. Paliyars are relatively the smallest tribal group living near the Western Ghats from Palni to Kanyakumari in Tamil Nadu as well as in some parts of Kerala. They were nomadic and had hunter-gatherer type of life style; due to the efforts by the Government and Non-Government organizations, they are now living in settlements; they have changed their occupation to sericulture, dairy farming, social forestry etc. Still some of them are involved in collecting non-timber forest products from the nearest forests.

Sathuragiri hills are one of the holy places in the Western Ghats in Virudhunagar district of Tamil Nadu. In Sathuragiri hills, there are about 36 paliyar hamlets; in Shenpagathoppu and Ayyanarkoil there are about 24 and 18 hamlets. We previously documented the local knowledge of non-institutionally trained Siddha practitioners of Virudhunagar district of Tamil Nadu, India (Esakkimuthu et al. 2019; Mutheeswaran et al. 2016, 2014, 2011) and few authors documented the folk medicinal knowledge of this district (Rajendran et al. 2002). Further there were few previous reports on the ethnobotany of paliyars (Aadhan and Anand, 2019, 2017a, 2017b, 2017c; Bose et al. 2014; Kamatchi and Parvathi 2020); they were qualitative in nature. This study was undertaken to quantitatively document the local knowledge of paliyars, a dominant tribe in the Sathuragiri Hills of the Western Ghats.

Methodology

The study area was in the Wattrap, Srivilliputhur taluk of Virudhunagar district between 11°00′ and 12°00′ N and 77°28′ and 78°50′ (Fig. 1). This communication is based on the data collected between April to November 2019 by series of interviews conducted among tribal healers. The tribal healers were identified by interviewing the elders in the society and by approaching tribal association named ‘vaṉakkuḻu’ in Virudhunagar district. The healers included in this survey were randomly selected. Their knowledge on medicinal plants was gathered after getting permission from the informants. The interviews were conducted in the local language ‘Tamil’. The protocols were in accordance with the guidelines of ISE code of ethics for ethnobiological research (International Society for Ethnobiology 2006). Successive free-listing method was used to gather the data (Heinrich et al. 2009). The questionnaire consisted of the following details: the local name of the plants, parts used, method of preparation, mode of usage and the symptoms treated. All the species cited as medicinal were collected from the field at reproductive stage in duplicate, with the help of informants. A field sheet was recorded with collector’s name, vernacular name, local abundance and ecological parameters. The herbarium samples were dried processed, identified taxonomically and the names were confirmed with the help of regional floras (Gamble and Fischer 1915; Henry et al. 1987; Matthew 1999, 1981; Nair and Henry 1983).

Fig. 1
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Map showing the location of the study area

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The data were converted into use-reports in accordance with previously published methods and they were grouped into illness categories. The consensus over a claim was assessed using consensus factor (Fic) (Heinrich et al. 1998; Trotter and Logan 1986). This factor can be given as: Fic = (Nur − Nt)/(Nur–1) where Nur is the number of use reports of informants for particular illness category, and Nt is the number of species used for particular illness by all informants. The consensus over the use of a species for an illness category was determined using Index on Agreement of Remedies (IAR). This factor can be given as: (nur − na)/(nr − 1) where nur is the total number of use reports for a species and nr is the number of illness categories which are treated by that species. These factors range from 0 to 1, where increasing values of this factor indicate high rate of informant consensus.

Results

The proportion of male healers was high than female. Regarding educational status of the healers only a few had school education and most of them were uneducated. This study recorded the ethno-medicinal usage of 139 species belonging to 124 genera under 52 families, which were used to prepare formulations (Table 1). Among them, 21 were shrubs, 12 were herbs, 96 were trees and 10 were climbers. Trees (69%) were found to be the dominant life form used by the tribals for medicinal purposes in Sathuragiri hills (Fig. 1). With regard to the plant families, Fabaceae had high number of species followed by Euphorbiaceae (Table 2, 3).

Table 1 Ethnomedicinal plants used by Paliyar tribe of Sathuragiri hills, Virudhunagar district, Tamil Nadu, India
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Table 2 Fic values for different illness categories reported by the Paliyar tribe of Sathuragiri hills, Virudhunagar district of Tamil Nadu, India
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Table 3 List of important plant species prescribed by the Paliyar tribe of Sathuragiri hills, Virudhunagar district of Tamil Nadu, India
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Gastrointestinal and pulmonary ailments were the major illness categories; out of 878 UR, 167 were for gastrointestinal ailments and 158 were on dermatological ailments. The illness categories viz., dermatological ailments and bites had high consensus over the other illness categories (Fic ≥ Average Fic + SD). In the case of dermatological ailments, 38 species had minimum two UR; among them Wrightia tinctoria, Pinus wallichiana and Curcuma neilgherrensis had high number of UR. The species like Gmelina asiatica and Boswellia serrata had high IAR values. In the case of bites, the species viz., Aristolochia bracteolata, Aristolochia indica and Anogeissus latifolia were the highly cited species; Macaranga indica also had high IAR value.

Twelve illness categories had average consensus (Fic < Average Fic + SD, but > Average Fic—SD); among them the gastrointestinal, musculo-skeletal and pulmonary ailments had high number of UR. In the case of wounds and fractures, the species such as Holoptelea integrifolia, Lawsonia inermis and Commiphora berryi had high number of UR; Bambusa bambos and Buddleja asiatica had high IAR. In the case of musculo-skeletal ailments, the species like Dodonaea viscosa subsp. angustifolia, Vitex negundo and Diospyros melanoxylon had high UR; Aristolochia bracteolata had high IAR. In the case of fever, Hugonia mystax had high number of UR; Gmelina arborea and Syzygium gardneri had high IAR value. Gastrointestinal ailments had high UR and in this illness category, 39 species had minimum two UR. The species such as Achyranthus aspera, Holoptelea integrifolia, Hardwickia binata and Ficus racemosa had high number of UR, under this illness category. In the case of oral ailments, Terminalia chebula had high UR; Wrightia tinctoria had high IAR. For treating gynecological ailments, Vachellia leucophloea, Momordica charantia and Melia azedarach had high number of UR; Calamus rotang and Dichrostachys cinerea had high IAR. In the case of male reproductive ailments, Moringa oleifera had high number of UR, while Momordica charantia had high IAR. In the case of neurological ailments, Vitex negundo had high UR; Neolitsea umbrosa had high IAR. For treating eye ailments, Spermacoce hispida had high UR and IAR. For the treatment of urinary ailments, Aerva lanata had high UR and IAR. In the case of pulmonary and respiratory ailments, Calotropis gigantea had high UR and Andrographis paniculata had high IAR. Four illness categories viz., blood ailments, general health, heart ailments and obesity had low consensus (Fic < Average Fic–SD).

This study recorded the medicinal uses of three endemic plants viz., Knema attenuata, Nothopegia colebrookiana and Miliusa eriocarpa and five threatened plants viz., Aglaia bourdillonii, Syzygium mundagam, Agrostistachys borneensis, Santalum album and Dalbergia latifolia.

Discussion

Collections of non-timber forest products like raw drugs, animal products and honey are the major sources of income for the informants and they had more than 15 years of experience with medicinal plants. This study highlights the local knowledge of paliyars in Sathuragiri hills and the need to conserve their knowledge. Fabaceae is the third largest family of the angiosperms with around 19,400 species; it is one amongst the five pharmacologically important families (Molares and Ladio 2012). Euphorbiaceae is also another major family with about 7,500 species; these species are mainly distributed in the tropics of Indo-Malayan region and America. In many cultures, Euphorbiaceae members were used extensively for their medicinal needs (Rahman and Akter 2013). In this study also, the members of Fabaceae and Euphorbiaceae occupied an important place.

There are wide array of dermatological ailments; due to their recurrence they seriously affect the quality of life. Further they have been reported as one of the common illnesses of rural people (Malik et al. 2019). Wrightia tinctoria is one of the widely used medicinal plants for dermatological ailments like psoriasis and non-specific dermatitis in India (Srivastava 2014). The antimicrobial efficacy of Pinus wallichiana and Boswellia serrata against various microbes including dermato-pathogens were reported (Shaik et al. 2014; Sinha 2019). Curcuma neilgherrensis is endemic to India and Indo-China and has been used to treat dermatological ailments also in other cultures (Yasodamma et al. 2013). In many cultures, the use of Aristolochia species is predominant; though it shows serious adverse effects, lack of modern diagnosis and latency in documenting the adverse events are worrisome (Grollman and Marcus 2016). Calotropis gigantea is a toxic plant, being used to treat venomous bites in India (Gaikwad et al. 2015). A preliminary study showed reduction in hemolysis, coagulation and edema by the treatment with the hydroalcoholic extract of C. gigantea (Pandey et al. 2011); robust experiments are needed to evaluate this effect.

Herbs are the primary source for the tribal people for treating wounds, cuts and fractures which happen during their field works in the forests; it might be the reason for high consensus. The species such as Holoptelea integrifolia (Reddy et al. 2008), Lawsonia inermis (Rekik et al. 2019) and Bambusa bambos (Davane and Nagoba 2016) had some preclinical evidences for their traditional usage to treat wounds. Musculo-skeletal ailments are the second cause of disability and where the usage of self-medications are high (Esakkimuthu et al. 2019). Our previous survey in Virudhunagar district also documented the use of Dodonaea viscosa and Vitex negundo for treating musculo-skeletal ailments (Mutheeswaran et al. 2011). Hugonia mystax was reported for the treatment of fever and showed antibacterial effect against many pathogenic bacteria (Rajeswari et al. 2012; Vimalavady and Kadavul 2012).

Gastrointestinal ailments are one of the highly cited illness categories in many ethnobiological explorations, since they represent a wide array of illnesses which are common in rural areas (Tangjitman et al. 2015; Tariq et al. 2015); our study is also in line with the previous surveys. The use of Achyranthes aspera for treating hemorrhoids was also recorded in our previous surveys (Pandikumar et al. 2011) and it has been in clinical use in ayurveda for treating hemorrhoids (Mahapatra et al. 2012). Likewise, the use of Ficus racemosa for treating various gastrointestinal ailments including hemorrhoids as also reported (Ahmed and Urooj 2010). The tannin rich bark decoction of Hardwickia binata was reported to treat diarrhea (Deshmukh and Ghanawat 2019). The aqueous extract of Terminalia chebula showed anticariogenic effect (Rekha et al. 2014). Treating the salivary samples of human subjects with 10% aqueous extract of T. chebula significantly reduced the microbial load (Carounanidy et al. 2007). Preliminary in vitro experiments indicated the antibacterial effect of Wrightia tinctoria against common dental pathogens (Khyade et al. 2014).

Use of astringents for treating various gynecological ailments like leucorrhea was reported in many ethnobotanical explorations and it might be reason for the use of species such as Vachellia leucophloea and Dichrostachys cinerea by the informants in our survey (Andel et al. 2015). The use of Melia azedarach for treating gynecological ailments was also reported previously (Mutheeswaran et al. 2014). For treating male reproductive ailments, the non-institutionally trained siddha practitioners of Virudhunagar district had high consensus (Mutheeswaran et al. 2011). The tribal healers of this study had average consensus and both surveys documented the use of Moringa oleifera. The use of Spermacoce hispida for treating inflammation of the eyes as reported (Conserva and Ferreira 2012). The use of Aerva lanata and its constituents like quercetin and betulin for treating urolithiasis was supported with preclinical studies (Dinnimath et al. 2017; Soundararajan et al. 2006). Our previous survey in Virudhunagar district also recorded the use of Calotropis gigantea for wheezing (Mutheeswaran et al. 2014); an arabinogalactan was reported from Andrographis paniculata with antitussive effect (Nosáľová et al. 2014). The uses of Syzygium cumini and Swietenia mahagoni for treating diabetes had considerable preclinical evidences (Helmstädter 2008; Sukardiman and Ervina 2020).

Conclusion

This is a first report from Sathuragiri hills, Western Ghats in Virudhunagar district which quantifies the medicinal plants used by Paliyars. The results of our exploration revealod the traditional uses of plants to treat nineteen illness categories; among them, dermatological ailments and bites had high importance. Twelve illness categories like gastrointestinal, musculo-skeletal and pulmonary ailments had average consensus; four illness categories had low consensus. Many of the claims had some scientific support; the use of potentially toxic species like Aristolochia bracteolata, Aristolochia indica, etc. warrants deeper investigations on their traditional medicinal practices and the local health. This study also documented the endemic and threatened plants used for medicinal purposes by the tribal healers in the study area. This study demonstrates that the traditional remedies need further attention to conserve this knowledge for future generation.