A total of 98 informants (54 males and 44 females) aged between 25 and 84 years were interviewed, in which 55.10% were males and 44.90% were females. The most number of informants was in the age group 45–64 years (Fig. 2). The illiteracy rate was 38.8%. Among the literate people, 29.6%, 19.4%, 10.2% and 2.0% had completed education up to primary, middle, secondary and university level, respectively (Table 1).
Phytodiversity, utilisation and its application
In the present ethnomedicinal survey, 75 species under 71 genera of 47 families were documented (Table 2), which are used for treating 41 types of disease. The most frequently used families as per the number of species are Asteraceae, Moraceae, Araceae, Euphorbiaceae, and Rutaceae. Analysis of the data based on habits showed that among the highly used plants, 41% were herbs, and 14.67%, 36% and 8% were shrubs, trees, and climbers, respectively (Fig. 3). Among the ethnomedicinal plants, 57.33% of the species were naturally growing, whereas 42.67% species were cultivated or planted. For each species, botanical name, local name (Bangla name), family, biological forms and treatment mode are presented in Table 3.
Among the recorded species, analysis of parts used revealed that leaves were the most used plant parts (50%), followed by stem (8.75%), root (7.5%), fruit (6.25%), bark (6.25%), latex (5%), rhizome (5%), whole plant (5%), seed (3.75%) and flower (2.5%) (Fig. 4). Herbal preparations can be made from roots, rhizomes, barks, stems or whole plant, which affect mother plants when they are collected . However, in the present study area, this threat was minimal because leaves were the most frequently used plant parts for medicinal purposes. It was observed that the collection of bark and whole plant as the medicinal part from the wild were not sustainable. According to local people, this type of activity is conducted by the collectors related to illegal trade of medicinal plants. Oroxylum indicum, Ricinus communis, Centella asiatica, Commelina benghalensis, Eclipta prostrata, and Scoparia dulcis are vulnerable to such activity in the study area.
Forms of medication
The most frequently used form of medication was juice (50.65%), followed by paste (20.78%), raw form (10.38%), infusion (3.90%), powder (3.90%), cooked form (3.90%), tablet (2.60%), ointment (2.60%), and syrup (1.30%) (Fig. 5). A plant preparation was turned into a herbal medicine in the form of juice, paste, tablet or ointment by mixing it in various food items, spices, or oil. Both external and internal modes of application of herbal medicine have been prescribed. Consequently, oral administration was predominant. Mostly, local herbalists prescribed fresh plant material as a source of herbal medicine. Usually, they do not store the herbal preparation.
Plant species used against diseases
Plants species are mostly used for treating dysentery (10 cases), rheumatism (10), skin disease (7), fever (5), hot flash (4), acidity (3), various types of pain (3), cough (3), diabetes (3), diarrhoea (3), heart disease (3), ascariasis (2), digestive (2), asthma (2), hair tonic (2), burn wound (2), constipation (2), excessive fat (2), faint disease (2), jaundice (2), haemorrhages (2), ulcer (2), ring worm (2), toothache (2), vomiting (2) and other diseases (16) (Table 3).
The most commonly used plant species in the study area were Aphanamixis polystachya, Azadirachta indica, Blumea lacera, Calotropis gigantea, Centella asiatica, Coccinia grandis, Eclipta prostrata, Kalanchoe pinnata, Lawsonia inermis, Litsea monopetala, Mikania micrantha, Ocimum basilicum, Oroxylum indicum, Scoparia dulcis, Psidium guajava, Stephania japonica, Streblus asper, Terminalia arjuna, Vitex negundo and Zingiber officinale. The recorded species in this study were previously recorded from various areas of Bangladesh as ethnomedicinal species [22, 26, 30]. However, the present study recorded seven new ethnomedicinal observations in Bangladesh. They are Pithecellobium dulce to treat dysentery, Stephania japonica to treat heart disease, Smilax ovalifolia to treat vertigo, leaves of Nymphoides indica and latex of Phoenix sylvestris to treat burns, leaves of Leea indica to treat skin diseases and Lasia spinosa to treat jaundice. Establishment of modern healthcare centres is in progress in many rural areas; this may gradually change the existing pattern of indigenous knowledge systems of healthcare . Field observations and discussion with local people demonstrated that the diversity of ethnomedicinal plant species and traditional knowledge of the area is at great risk because of threats including habitat destruction; exotic monoculture plantations; agricultural development; degradation of village groves and construction of buildings for housing, commercial farms and industry.
The ethnomedicinal plants of the study area exhibited diverse habitats, such as homestead area, cultivated land, scrub jungles, fallow lands, and wetland. The present generation is losing interest to continue their parental profession because it does not provide them proper financial support for their livelihood [5, 7]. Hence, the documentation of these traditional uses of plant species as herbal medicine is essential before they disappear permanently.
Use reports and FIC
In the ethnomedicinal studies, informant’s consensus analysis provides a measure of consistency for the given claim of evidence . The studied upazila had a significant variety of plants with traditional uses against diseases. A total of 41 diseases were grouped into 13 therapeutic categories based on the information gathered from the interviews (Table 4).
The FIC was calculated for each ailment category, and the range was from 0.71 to 0.91. Given results of the FIC showed that the category of hormonal disorder had the highest value with 0.91%, wherein the root of Bombax ceiba and whole plant of Eclipta prostrata were reported by the informants to be used for treating sexual diseases and leucorrhoea, respectively. The root of Bombax ceiba is used for treating impotency, gonorrhoea and improving the functionality of the sexual organ [32, 33]. The second highest FIC value (0.87%) was calculated for endocrine disorder category, which included the reported use of Coccinia grandis, Ficus racemosa, and Syzygium cumini. These three plant species have anti-diabetic property [34–39]. The similar FIC value (0.85%) was exhibited by cardiovascular and respiratory system disorders. Gastrointestinal disorders, dental care and liver or hepatobiliary disorders exhibited the value as 0.83%. The category of external injury or bleeding and burn wound exhibited the lowest FIC value. This study implied that the medicinal plants for treating several ailments is still in practice by different indigenous people and it can attract future generations towards traditional healing practice.
For each of the 14 most commonly used plant species as ranked by the informants, the FL (Table 5) was calculated to quantify their importance in treating a major ailment [40, 41]. The remedies for frequently reported ailments have the highest FL values, and those with a low number of reports have the lowest FL values . This study showed a high FL of >60% for 9 plant species, which highlighted the importance of these species in the treatment of the frequently mentioned diseases in the study area. The highest FL value (93.3%) was exhibited by Cynodon dactylon, followed by Aegle marmelos (88.9%), and Paederia foetida (81.8%), (Table 5). The high FL levels for these species indicated their outstanding preference for treating most of the gastrointestinal disorders and haemorrhages. Additionally, Nyctanthes arbor-tristis (77.8%), Coccinia grandis (75.0%), and Lawsonia inermis (75.0%) had high FL values (Table 5).