DETERMINATION OF LOCAL PEOPLE CONSENSUS IN THE USE OF MEDICINAL PLANTS OF THAKURGAON DISTRICT

Consensus in the use of medicinal plants is one of the criteria to find the potential medicinal plants for further in-depth investigation. The present study was conducted with the aim to determine the people consensus in the use of medicinal plants in Thakurgaon district. Data of medicinal plants were recorded using key informant interviews, semi structured interviews and group discussion. A total of 102 medicinal plant species under 49 families with 185 formularies to treat 54 ailments were recorded from the study area. The most frequently utilized plant species are trees (38%) followed by herbs (34%), shrubs (18%) and climbers (10%). The major part used for medicines was leaf. Oral consumption was the main mode of treatment in the study area followed by external application. The top Fic value was obtained in case of heart diseases (0.92). The most cited species used to treat this ailment was Allium sativum , Phyllanthus emblica , Spondias pinnata and Terminalia arjuna . The second highest Fic value was found in respiratory disorders (0.89) followed by cuts and wounds (0.85), skin diseases (0.84) and gastrointestinal disorders (0.81). In case of Fl value, Allium sativum , Spondias pinnata , Cynodon dactylon, Lawsonia inermis, Zingiber officinale, Saccharum officinarum, Tagetes erecta and Baccaurea ramiflora were showed 100%. The species of higher citation frequency were Allium sativum, Phyllanthus emblica, Spondias pinnata, Terminalia arjuna, Cynodon dactylon and Ocimum sanctum . This study recommends that the species which showed high Fic, Fl, Cf values could be used for further phytochemical analysis to investigate active compounds for the discovery of new drugs from medicinal plants.


Introduction
Ethnobotanical investigation is the gateway in identifying new plant products of potential commercial values . Documented medicinal plants with high degree of consensus can serve as a basis for future investigation of modern drug (khan et al., 2014). The world market for herbal medicines based on traditional knowledge is now estimated at US$ 60 billion (Breevot, 1998). In 1992, the world leaders met in Rio de Janeiro to formulate biodiversity conservation policy including agenda 21 which also gave emphasis on the documentation and sustainable utilization of traditional knowledge of medicinal plants. Indigenous knowledge of using medicinal plants for healing human ailments is however in danger of gradually become extinct, because this knowledge is passed on orally from generation to generation without the aid of a writing system (Kaido et al., 1997). Most culture possess a huge store of undocumented traditional knowledge of applying herbal remedies in the treatment of diseases (Offiah et al., 2011). In addition, documenting the results of scientific research into traditional medicine may also help to conserve an important part of an indigenous people's cultural heritage for the future generations (Mahwasane et al., 2013). Ethnobotanical studies have got attention in all over the world. Unless the plants are conserved and the ethnobotanical knowledge is documented, there is a danger that both the valuable medicinal plants and the associated indigenous knowledge of the ethnic groups could vanish forever due to lack of documentation.
The documentation of indigenous knowledge of herbal medicine is an important aspect of conservation approach (Umair et al., 2017). Many studies have been done on indigenous knowledge of medicinal plants in different parts of Bangladesh. Today a substantial number of drugs are developed from plants which are active against number of diseases (Principe, 2005). In spite of tremendous advances in synthetic drugs and medicine, a large number of people still believe on herbal drugs with hope of safety and efficacy (Verma et al., 2008). Plants may serve as the alternative sources for the development of new anticoagulant agents due to their biological activities.
Currently medicinal plants and traditional knowledge have been eroding because of anthropogenic pressure, deforestation, pollution, modern agriculture practices, lack of awareness, unwilling to practice forefather tradition, climate change, modern culture, migrating towards urbans and no written documents. Some of such knowledge is going to be eliminated before documentation which is alarming to sustain cultural heritage (Uddin et al., 2017). So, it is essential to document all traditional knowledge about herbal medicine and all medicinal plants. In order to protect such knowledge, documentation of ethnobotanical plants is already started in Bangladesh. A number of articles have been published in this field, for example, Mia and Huq (1988), Khan (1986, 1996), Alam (1992), Alam et al. (1996), Uddin (2006), Uddin et al. (2001), Khan et al. (2002), Yusuf et al. (2002), , Uddin et al. (2006), Yusuf et al. (2006), Uddin and Roy (2007), Uddin et al. (2008), Uddin et al. (2012), Haque et al. (2014) and Uddin and Hassan (2014), Kona and Rahman 2016, Nahar et al. 2016, Faruque et al. (2018,2014 and Uddin et al. (2019). These articles listed a good number of medicinal plants of particular community or particular diseases or particular areas of Bangladesh. But there are still more medicinal plants which are being used as the sources of herbal drugs by the ethnic and local people of Bangladesh but yet to be identified scientifically. Unfortunately, no such work has covered the documentation of ethnomedicinal plants of rural people of Thakurgaon district.
The houses homesteads of rach village of Thakurgaon are rich with natural plant diversity in its unique original ecosystems. The indigenous livelihood is mainly based on cultivation system. They mainly cultivate rice as a principal food and also cultivated other diversity of minor crops in and around their homes. Many indigenous species are disappearing from the area as well as many new invasive, alien species are occupying its habitats. Such loss of indigenous species might have an adverse effect on the food security and livelihoods of the area. So, there is a great necessity for recording the existing medicinal plant species through adequate ethnobotanical studies in the area before their disappearance from the natural habitats. Traditional practitioners of the area also use the medicinal plants in the treatment of various diseases. Currently medicinal plants, healthcare knowledge of medicinal plants and their habitats are vulnerable because of many threats such as lack of awareness, deforestation, urbanization, agricultural expansion, illegal logging and poaching etc. If the situation continues, important medicinal plants will be eliminated before their documentation. In the present study an attempt was made to record ethnomedicinal use of plants and to determine the consensus of local people in the use of medicinal plants for the treatment of ailments.

Materials and Methods
Thakurgaon is a district in the northwest of Bangladesh under Rangpur division. It is located between 25°40' and 26°12' N latitudes and 88°05' and 88°39' N longitudes. The district is bounded by Panchagarh district on the north, Panchagarh and Dinajpur districts on the east, and the West Bengal state of India on the south and west. This district consists of six thanas named as Thakurgaon Sadar, Ruhia, Baliadangi, Pirganj, Ranishankail, and Haripur. The climate of the district is mainly tropical dry with late monsoon. The monsoon usually begins in June and ends in October, with an average rainfall of 1700 mm. The summer average temperature is 31 °C, and the winter average temperature is 19 °C (Banglapedia, 2014). There are five forest beats present in the Thankurgaon forest range. The most dominant species in such forest beats is Sal (Shorea robusta). A good number of herbs, shrubs, and climbers are grown with dominant Sal trees those may have medicinal values (personal communication and observations).
The study area was visited five times in different seasons of 2018 and 2019. Each field trip lasted for five to eight days. The data on medicinal uses were collected through semi-structured interviews, key informant discussions, and informal conversations with local people and also herbal practitioners. Participant observation, plant interview, field interview, and group interview were also followed to collect data (Alexiades, 1996). A total of 250 local informants, including 58% males and 42% females, were interviewed during the ethnobotanical survey. The education levels of the informants ranged from illiterate up to B.S. degrees. The informants were mainly farmers, housewives, herbal practitioners, shopkeepers, businessmen, teachers, and students. The age of the informants ranged from 21 to 80 years. Information on the uses of plants to treat humans, parts used, modes of treatment, and administration were collected during the field survey. The vernacular names were collected with the help of the local people. The recorded medicinal plants were collected from fields and gardens with notes on field characters. Voucher specimens for each medicinal plant were processed using standard herbarium techniques (Hyland, 1972 andAlexiades, 1996). Identification of plant species was done by experts in both the field and laboratory and consulting standard literature (Siddiqui et al., 2007;Ahmed et al., 2008Ahmed et al., -2009. In case of confusion in identity, standard literature was consulted, and relevant voucher specimens available at the Dhaka University Salar Khan Herbarium (DUSH) were also compared. All voucher specimens were deposited at DUSH. To determine people's consensus in the use of medicinal plants, factor informant's consensus (Fic), fidelity level (Fl), and citation frequency (Cf) values were calculated using standard mathematical models according to Heinrich et al. (1998) andFriedman et al. (1986).

Results and Discussion
Present study was recorded a total of 102 medicinal plant species under 49 families. These medicinal plants were used for the management of 54 aliments through 185 formularies in the study area. Maximum medicinal plant species (67%) were found under 17 families and rest medicinal plants species (37%) were found in 32 families (Fig. 1). Among the families, Araceae, Rutaceae, Cucurbitaceae, Poaceae, Fabaceae, Liliaceae, Solanaceae, Verbenaceae, Asteraceae, and Caesalpiniaceae were the dominant families with the common medicinal plant species in the study area. For each species, the scientific name, local name, family, habit, parts-use, ailments, and modes of treatment have been presented in the Table 1. It is evident from a preliminary investigation that the study area still has a huge variation of knowledge about the uses of medicinal plants. Such knowledge has been passed down orally from generation to generation and no written document found on this knowledge. Plant species recorded as medicinal plants were classified into trees (38%), herbs (34%), shrubs (18%), and climbers (10%) (Fig. 2). It was observed that local people use trees more than herbs, shrubs, and climbers to cure different kinds of diseases. They took these medicinal plants because of their easy availability in collection, lack of side effects, and abundance in the area. In the present study, different plant parts are used in the treatment of different ailments, which were also documented. Leaves were the leading parts used (Fig. 3). From the present study, it was observed that 79% of treatments were taken internally and 21% were applied externally (Fig. 4). These data indicated that Thakurgaon district still supports rich medicinal plants with diverse applications. The reported ailments in the study area were classified into 8 different major disease categories to calculate the Fic values including heart diseases, gastrointestinal disorders, diabetes, skin diseases, respiratory disorders, cuts and wounds, jaundice and kidney diseases, and others. The results could be useful in prioritizing medicinal plants for further scientific validation of plant products as pharmacologically effective remedies with higher Fic values. The product of this factor ranges from 0 to 1. A high value (close to 1.0) indicates that relatively few taxa are used by a large proportion of the informants. A low value indicates that the informants disagree on the taxa to be used in the treatment within a category of illness. Higher Fic values can thus be used to pinpoint particularly interesting species for the search of bioactive compounds. Maximum values of Factor of Informant Consensus (Fic) were obtained in the cases of heart diseases (0.92) followed by respiratory disorders (0.89), cuts and wounds (0.85), skin diseases (0.84), gastrointestinal disorders (0.81), and others (0.58) ( Table 2).

Category
No. of use report ( Nur) In order to identify medicinally important plant species in the study area, the fidelity level (Fl) was calculated. The medicinal plants that are widely used by the local people for particular ailment have a higher value than those that are less used. The fidelity level (Fl) of the 15 most important plant species ranged from 60.98% to 100% (Table 3). Allium sativum L., Spondias pinnata (L. f.) Kurz, Cynodon dactylon (L.) pers., Lawsonia inermis L., Zingiber officinale Rosc., Saccharum officinarum L., Tagetes erecta L., and Baccaurea ramiflora Lour. species showed 100% fidelity level (Fl). Medicinal plant species obtained maximum Fl value is the valid indication to investigate further for new drugs.
Citation frequency was calculated to determine the most popular medicinal plants in study area. A total of 11 medicinal plant species of different citation values are presented in the Table  4. Allium sativum L. is the most cited species in study area. Second cited medicinal species is Phyllanthus emblica L. These two medicinal plant species are very popular in the study area to treat heart disease.
Ethnobotanical information is today recognized as the most effective method of identifying new medicinal plants or refocusing on those plants reported in earlier studies for the possible extraction of beneficial bioactive compounds. At the global level, about 80% of local people depend on old-style herbal systems to cure their health disorders. In the past, due to a shortage of doctors and hakims, people used medicinal plant species for various diseases because they were considered to have fewer side effects and could be easily obtainable. Ethnobotanical knowledge is transferred from generation to generation, but without proper documentation, such knowledge may disappear. In the present study, carried out in Thakurgaon district, 102 plant species have been used for the treatment of different ailments. The present ethnobotanical survey showed that there is variation in the uses of medicinal plants by the local people. Among the plant parts, leaves were the most commonly utilized plant parts for the preparation of plant-based medicine, which was similar to (Uddin et al., 2017;Sajib and Uddin, 2013). It has been reported that the use of leaves is better for the survival of medicinal plants compared to the whole plant, roots, and stem, which may pose a severe threat to the local flora (Zheng, 2009).
From the present study, the maximum number of species under 49 families were identified for the treatment of several diseases. Among them, Araceae and Rutaceae were the most commonly used families for medicinal purposes, followed by Cucurbitaceae, Poaceae, Fabaceae, Liliaceae, Solanaceae, Verbenaceae, Asteraceae, and Caesalpiniaceae in the study area. The most commonly cited mode of preparation is juice, which is made by the local people of the study area. There are many other modes of preparation of medicine, such as paste, decoction, crushing, and cooking. Maximum local people are administered orally or internally. The results are supported by Uddin et al. (2017) and Uddin et al. (2015), who observed the same in different regions of Bangladesh.
Highest Fic values were found in cases of heart dieases. The most commonly cited species used to treat this ailment are Allium sativum L., Phyllanthus emblica L., Spondias pinnata (L.f.) Kurz, and Terminalia arjuna (Roxb. ex DC.) Wight & Arn. Another report showed that the bulb of Allium sativum L. is used to reduce chest pain, relieve pressure, and treat ringworm . Terminalia aurjuna (Roxb. ex DC.) Wight & Arn. is used for the treatment of heartache, which is also used for the same purpose reported from different areas of Bangladesh (Uddin et al., 2012;Uddin and Hassan, 2014). This plant is also used for stomachache, cough, diabetes, menstruation, gastric pain, and dysentery (Uddin et al., , 2012(Uddin et al., , 2017Islam et al., 2014;Uddin et al., 2015a, b). Terminalia arjuna (Roxb. ex DC) Wight & Arn. is a popular Indian medicinal plant, and its bark has been used for over centuries as a cardiotonic. The cardioprotective effects, particularly of the bark of Terminalia arjuna (Roxb. ex DC.) Wight & Arn., are well known. Such species can be used for further phytochemical analysis to find active compounds for heart disease (Uddin et al., 2019). Respiratory disorders scored the second-highest Fic values. Ocimum sanctum L., Zingiber officinale Rosc., and Adhatoda vasica Nees are the most cited species used to treat respiratory disorders. Ocimum sanctum L. showed the highest Fic value among them. Another study from Bangladesh found that the plant species Ocimum sanctum L. was also used for the treatment of cough disorders (Uddin et al., 2017;Sajib and Uddin 2015;. The third highest Fic value was found for cuts and wounds. The most cited plant species was Cynodon dactylon (L.) Pers., used for the treatment of cut injury (similar to Khan et al., 2002, Uddin et al., 2017Khatun and Rahman, 2018;Yasmin and Rahman, 2017). In the present study, Allium sativum L., Spondias pinnata (L. f.) Kurz, Cynodon dactylon (L.) Pers., Lawsonia inermis L., Zingiber officinale Rosc., Saccharum officinarum L., Tagetes erecta L., and Baccaurea ramiflora Lour. showed 100% fidelity level (Fl). Allium sativum L. obtained the highest Cf value, meaning that such species are very important plant species in the study area. Phyllanthus embelica L., Spondias pinnata (L. f.) Kurz, Terminalia arjuna (Roxb. ex DC.), Cynodon dactylon (L.) Pers., and Ocimum sanctum L. were also the most cited plant species in the study area.
Phytopharmacological investigation has led to the discovery of plant-derived drugs that are effective in the treatment of certain diseases and has renewed interest in plant-based medicines. Therefore, these species should be increased and protected in the area. The present analysis has confirmed their popularity among the local people of the Thakurgaon district. The present survey revealed that 103 medicinal plant species were used for 54 ailments with 185 formulas by the local people of the study area. The record of 103 medicinal plant species is an indication of rich ethnobotanical knowledge among the local people of Thakurgaon district.
Consensus of people in the use of medicinal plants has resulted in the recording of 102 medicinal plant species under 49 families with 185 formularies to treat 54 ailments. The present results are the indication of rich medicinal plant species with variation of health care knowledge in Thakurgaon. The results of this study will be useful in selecting potential medicinal plants for further study to find new sources of drugs. The top Fic (Factor informant consensus) value was obtained in case of heart diseases (0.92). The most cited species used to treat this ailment are Allium sativum L., Phyllanthus emblica L., Spondias pinnata (L.f.) Kurz, and Terminalia arjuna (Roxb. ex DC.) Wight & Arn. The second highest Fic value was found in respiratory disorders (0.89) followed by cuts and wounds (0.85), skin diseases (0.84) and gastrointestinal disorders (0.81). In case of Fl (Fidelity level) value, Allium sativum L., Spondias pinnata (L.f.) Kurz, Cynodon dactylon (L.) Pers, Lawsonia inermis L., Zingiber officinale Rosc., Saccharum officinarum L., Tagetes erecta L. and Baccaurea ramiflora Lour. showed 100%. According to the Cf (Citation frequency) the most cited species are Allium sativum L., Phyllanthus emblica L., Spondias pinnata (L.f.) Kurz, Terminalia arjuna (Roxb. ex DC.) Wight & Arn., Cynodon dactylon (L.) Pers. and Ocimum sanctum L. From the study of people consensus, it is recommended that species which showed high Fic, Fl, Cf values could be used for further ethnolead phytochemical analysis to investigate active compounds for the discovery of drugs from medicinal plants. The present study also revealed that the medicinal plants and traditional knowledge of such plants in the Thakurgaon district are in a threatened condition due to different disturbances, and some suggestions have been made for sustainable conservation. The findings of the present study are very preliminary. Further long-term studies are needed.