Study area The study was conducted in Batiaghata Upazila under Khulna district. It is located between 22°46´07´´ N to 22°37´50´´ N and 89°24´14´´ E to 89°31´47´´ E (Figure 1). Batiaghata experiences a subtropical climatic condition with a mild winter from October to March, hot and humid summer in March to June and moist, warm rainy monsoon in June to October. In December-January, the temperature fell to the lowest at 12-15°C, and it reached highest in April-June at 41 -45°C. Most of the rainfall during June to October. July is the month of maximum precipitations with 20-25 days of rain. Average wind speed is over 8 km/h during April-August, which is the highest value for this area (BBS, 2014).
Demography Like other Upazilas of Bangladesh, Batiaghata is densely populated with a total population of 140,574 in which 72,717 are males and 67,857 females with 40,779 units of households. Among the total population, Muslims dominate with 79,301 along with 60,894 Hindu, 285 Buddhist, 6 Christian, and 85 others. Administratively, Batiaghata Upazila has seven unions named Amirpur, Baliadanga, Batiaghata, Bhandarkote, Gangarampur, Jalma, and Surkhali. Almost 91% of people are engaged in agriculture, followed by service (7%) and industry (2%) (BBS, 2011, 2013).
Sampling design A reconnaissance survey was conducted in the study area before questionnaire preparation to obtain general information about the villages and the villagers. Depending on this survey, a semistructured questionnaire was prepared for ethnobotanical information collection. Five unions (Batiaghata, Baliadanga, Gangarampur, Amirpur and Surkhali) have been selected and one village from each union was chosen to survey by random selection. In total, 150 households were studied in this study, where 30 houses were chosen randomly from every village for data collection. Interviewees were divided into five age groups (20-34, 35- 49, 50- 64, 65-79, 80 and above) as age plays a distinctive role in ethnobotanical knowledge (Nawash et al., 2014). Cited plant species were checked physically, photographed, and voucher specimens were collected for further identification and conservation. Collected specimens were analyzed and identified based on the key provided by Hooker (1872-1890), Prain (1903- 04), Kanjilal et al. (1934-1940), Deb (1983), Matthew (1999) and Ahmed et al. (2007-09).