Ethnobotanical survey of medicinal plants used by Malayali tribes in Jawadhu hills of Eastern Ghats, Tamilnadu, India

An ethnobotanical survey was carried out to collect information from the Malayali tribes of Jawadhu hills, Thiruvannamalai district, Tamilnadu, India from August 2016 to July 2017. A total of 63 plant species belonging to 32 families were distributed into 55 genera, which were commonly used by the local Malayali tribes for the treatment of various diseases such as headaches, fevers, asthma, coughs, colds, wounds, snake bites, piles, stomach disorders, skin diseases, gastric ulcers, kidney stones, urinary infection, diabetes, jaundice, inflammation etc. In the present study, Acanthaceae, Euphorbiaceae, Amaranthaceae, and Asclepiadaceae are the most dominant families used in the treatment of various ailments. Generally, leaves are used to prepare herbal medicine. The ethnomedicinal plants used by the Malayali tribes were arranged alphabetically followed by botanical name, family, local name, medicinal uses and mode of administration.


INTRODUCTION
Ethnobotany deals with the study of relationships between humans and indigenous plants. Plants are an important source in the preparation of herbal drugs and play a significant role in the survival of tribal and indigenous people throughout the world. According to the World Health Organization (WHO), it is estimated that more than 80% of the world population relies on traditional medicines, mostly plant drugs, for their healthcare needs (Kala et al., 2006). In developed countries, 25% of herbal medicines are used to treat chronic as well as infectious diseases. The indigenous people in rural areas have a vast knowledge of how to use plants for the treatment of various diseases. In India, about 1.5 million indigenous people use plant drugs as a traditional medicine for preventive and curative purposes. The tribes and indigenous peoples in India use more than 6,000 of 15,000 herbal plant species as herbal medicine (Dhamija et al., 2011).
The tribal and indigenous people have a strong faith in herbal native traditional medicine to cure diseases. Generally, every tribal group has a wide range of ethno-medicinal knowledge for the identification of medicinal plants and also has a unique and different technique for using these herbs for the treatment of various diseases. In India, some tribal groups have started to use allopathic medicine along with ethnomedicine. But still, there is a lack of documentation of indigenous knowledge of herbal medicine. So awareness should be created among the tribal and indigenous people to explore their ethnomedicinal knowledge for the treatment of diseases. The current study aimed to document indigenous knowledge on medicinal plant species used by local Malayali Tribes in the Jawadhu Hills, Thiruvannamalai district, Tamilnadu, India.

Study Area
Jawadhu Hills are located in the Southern Eastern Ghats, spread over Vellore and Tiruvannamalai districts of Tamil Nadu. The Jawadhu Hills cover an area of 80 km wide and 32 km long. It is bisected into western and eastern parts by three major rivers, viz., Cheyyar, Agaram, and Palar. The altitude of the Jawadhu Hills ranges from 1100 m to 1150 m above mean sea level. It is located between 12.5833° N latitude and 78.8333° E longitude. Jawadhu Hills is a humid subtropical climate area mainly occupied by Malayali tribes (98%) and others (2%). The vegetation of the study area falls under the moist and dry deciduous forest types (Figure 1).

Data Collection
An extensive field survey was carried out to get information on the medicinal plants from the Malayali tribes in the study area. In order to document the existing information on the medicinal plants from tribal practitioners, several field trips were carried out from August, 2016 to July, 2017 in the Jawadhu Hills. During the study, the ethnomedicinal information was collected from middle-aged and older tribal practitioners in their local language, Tamil, through direct interviews, questionnaires and discussions.
The information on the local name of the plant, parts of the plant used, method of preparation and mode of administration (i.e., paste, powder, juice and decoction) of all collected ethnomedicinal plants was recorded during the survey period. The collected ethnomedicinal plants were identified by using The Flora of the Presidency of Madras (Gamble, 1935) and The Flora of Tamil Nadu Carnatic (Matthew, 1983). Further, the identification was confirmed by referring to authentic specimens deposited at the Botanical Survey of India, Southern Circle, Coimbatore.

RESULTS AND DISCUSSION
The present study revealed that a total of 63 plant species belonging to 32 families were distributed into 55 genera, which were commonly used by the local Malayali Tribes for the treatment of various diseases. The most commonly represented families were Acanthaceae (8 species), followed by Euphorbiaceae (5 species), Amaranthaceae and Asclepiadaceae (4 species each), and the remaining 28 families were represented by less than 4 species in the study forest, Jawadhu Hills. The most represented genera are Cassia (3), Achyranthes, Barleria, Euphorbia, Phyllanthus, and Sida (2) in the studied plants (Table 1).
Tribes are using these plants to cure diseases like headaches, earaches, sore throats, fevers, viral fevers, asthma, cough, cold, blockage of nose, wounds, snake bites, insect bites, scorpion stings, antidotes, piles, gonorrhea, stomach aches, stomach disorders, psoriasis, skin diseases, ringworm, gastric ulcer, kidney stone, urinary infection, antiseptic, gallstones, arthritis, diabetes, wheezing, ulcers, joint pains, inflammation, rheumatism, infection fingers, traumatic, folkloric, hair growth, diabetes, leucoderma, jaundice, leprosy, anti-fertility, bronchitis, tooth diseases, antidepressant, dyspepsia, and eye inflammation. The different parts of plants were used to prepare medicines in the form of paste, powder, juice, decoction, and oil. Further, it was observed that some of the plants were used in more than one form of mode of preparation (Table 1).

CONCLUSION
The present investigation was aimed to record the ethnomedicinal knowledge of plants used for the treatment of various diseases by the Malayali tribes of Jawadhu hills. Medicinal plants still play a major role in the primary health care of the tribes. The Malayali tribes of the Jawadhu hills have been using several medicinal plants for therapeutic purposes. The tribes depend on these plants for the treatment of various diseases such as headaches, fevers, asthma, coughs, colds, wounds, snake bites, piles, stomach disorders, skin diseases, gastric ulcers, kidney stones, urinary infections, diabetes, jaundice, inflammation etc. Furthermore, it is also observed that some medicinal plants in that area are destroyed. So there is a need to create awareness among tribes for documentation, sustainable utilization and conservation of such medicinal plants.