Ethnomedicinal uses of plants by Santal Tribal peoples at Nawabganj upazila of Dinajpur district, Bangladesh

Ethnobotanical investigation on traditional medicinal plants used by Santal tribal people of Nawabganj upazila of Dinajpur district, Bangladesh was documented. Frequent field trips were made during January to December 2018 to record ethnobotanical data by interviewing Santals of various age group, mostly ranging between 20-76 years, including the traditional healers. A total of 105 plant species under 97 genera belonging to 57 families were recorded which are used by the Santals for the treatment of 67 ailments. Out of these plant species 44% belonged to herbs, 28% trees, 18% shrubs, 10% climbers. In herbal formulations, leaves were found to be mostly used (29%) followed by roots (12%), fruits (12%), whole plant (10%), seeds (9%), barks (9%), stems (5%), flowers (4%), latex (2%), rhizomes (2%), petioles (2%), gums (2%), bulbs (1%), tubers (1%), pods (1%) and buds (1%). The Santal medicinal wealth have been presented with scientific name, family, Bangla name, Santal name, part(s) used, ailments to be treated and formulations. This study also provides data on diversity, distribution and habitats for conservation and prioritization of the medicinal plants.


Introduction
The use of plants and animals as source of medicine and food is as old as humanity. Health and diseases are coeval with life. By necessity man has undoubtedly always been concerned with the question of health and survival and has sought within the framework of his knowledge, solution to problem of illness (Rubin, 1960). The herbal occupied a distinct place in the life right from the primitive period to today and the primitive or ethnic populations have their own medical lore, and some of their therapeutic practices have found place in today's medical knowledge (Jain, 1995). This traditional knowledge is useful to develop new food sources. Exploration of natural resources and documentation of traditional knowledge is necessary.
Even today, traditional medicine is still the predominant means of health care in developing countries where about 80% of their total population depends on it for their well being. Plants are the basis for the development of modern drugs and medicinal plants have been used for many years in daily life to treat disease all over the world. However, the knowledge of medicinal plant is rapidly dwindling due to the influence of Western lifestyle, reducing in number of generations to carry on the use of plant species in traditional medicine which has increased the interest throughout the world. World Health Organization estimates that 80% of populations from many countries are using traditional of folk medicine to cure various ailments (WHO, 1991).
Over the past two decades several medicinal and ethno-botanical studies in Bangladesh have been carried out by Alam (1992); Alam et al. (1996); Anisuzzaman et al. (2007); Choudhury and Rahmatullah (2012); Faruque and Uddin (2014); Khan (1998); Khisha (1996) and Yusuf et al. (2006Yusuf et al. ( , 2009. However, the studies on traditional knowledge of medicinal plants of this country is very incomplete. The tribal people of Nawabganj, Dinajpur mostly rely on traditional medicines directly based on plant materials (Ali, 1980). The present work is an attempt to explore the traditional knowledge of medicinal plants in Nawabganj upazila of Dinajpur district, Bangladesh. In this study the local uses of plants recorded from the traditional practitioners to cure different diseases in Nawabganj upazila of Dinajpur district, Bangladesh are described.

Study area:
Nawabganj is an upazila of Dinajpur district which is one of the northern districts of Bangladesh. Total area of this upazila is 314.68 sq km, located in between 25°14' and 25°34' north latitudes and in between 88°58' and 89°13' east longitudes. It is bounded by Parbatipur upazila on the north, Ghoraghat and Hakimpur upazilas on the south, Pirganj (Rangpur), Mithapukur and Badarganj upazilas on the east, Birampur and Phulbari upazilas on the west. Here annual average highest temperature 33.5 o C and lowest 10.5 o C and annual rain fall 2,536 mm. (BPC, 2001).

Data collection:
A total of twenty nine field trips were completed for the documentation of medico-botanical knowledge during January to December 2018. During the field interview, the information was noted in the documentation data sheet. All the information regarding plant species, biological forms, habitat, local names and uses were documented. Medicinal information was obtained through semi-structured interviews with knowledgeable Santals, such as Kabiraj and elderly persons. A total of 134 informants having age range of 20-76 years were interviewed using semistructured interview method. Professionally they were peasant, day labor, farmer, betel leaf cultivators, house wives, medicine men, small shop keepers etc. Among them 58 were female and rest 76 were male. Plant specimens were collected with flowers and fruits and processed using standard herbarium techniques (Alexiades, 1996).
During the survey, the discussion, interviews and field visits with traditional healers, kabiraj, herbalists, medicine men, indicated that they have enough knowledge of medicinal uses of plant species. Traditional knowledge of tribal and local people on human disease is very important to find out new drugs for human health, also the doses and their administration needs to standardization with scientific way. Deforestation, civilization, development projects, modernizations and industrialization etc. are largely depleting the biodiversity and natural habitat of these species as well as the traditional knowledge. Conservation initiatives with in situ or ex situ conservation activities before these medicinal plant resources lost forever and training of the young generation on use and conservation of these medicinal plants are very necessary. The results of this study will play a role in primary health care of human and be helpful in further ethnobotanical studies.