ANGIOSPERM FLORA OF SADAR UPAZILA OF MUNSHIGANJ DISTRICT , BANGLADESH

Investigation to make inventory of the angiosperm species diversity in the local flora of Sadar Upazila of Munshiganj district has been made. A total of 240 taxa in 186 genera under 68 families are recognized, and enumerated citing each species with updated nomenclature, Bangla names, habit, habitat, phenology, potential value, status of occurrence in the area and voucher specimens. Of these 240 taxa, Magnoliopsida is represented by 195 taxa in 146 genera and 55 families, whereas Liliopsida by 45 taxa under 40 genera and 13 families. The local people of the area use over 50 medicinal plants as sources of medicine for their primary health care. Some species are assessed as rare to this local flora which need to be brought under conservation management for environmental sustainability of the area. Introduction Munshiganj Sadar, an administrative Upazila of Munshiganj district comprises an area of 160.79 sq. km., and is consisted of 9 administrative unions, namely Adhara, Bajra Jogini, Char Kewar, Char Siloi, Mahakali, Mollakandi, Panchasar, Rampal and Rekabi Bazar. The Upazila witnesses the same climatic condition as other parts of the district. The hot summer, the long rainy season and the pleasant spring-cum-winter are the main noticeable seasons prevailing in the locality. The temperature of the area fluctuates between 12.7 ̊C and 33.7 ̊C throughout the year. Monthly average relative humidity varies from 62 to 83%, and monthly rainfall ranges from 7.7 to 373.1 mm throughout the year (BBS, 2011). There are three types of soil in the adjoining areas of Munshiganj Sadar Upazila, viz., heavy clayey soil that prevails over the major part of the study area, light clayey soil which occupies the second position in the area, and heavy loamy soil prevails over small area. The Upazila presents diverse habitats including scrub jungles, homesteads, char lands, riparian, roadsides and wetlands. Over the last few decades several attempts have been made on the floristic studies in Bangladesh, particularly in the forest and protected areas (Khan and Afza, 1968; Khan and Banu, 1972; Khan and Hassan, 1984; Rahman and Hassan, 1995; Rahman and Uddin, 1997; Uddin and Rahman, 1999; Khan and Huq, 2001; Uddin and Hassan, 2004; Tutul et al., 2009, 2010; Arefin et al., 2011; Uddin and Hassan, 2012). Studies on angiosperm flora in different Upazilas of Bangladesh are limited (Islam et al., 2009; Rahman et al., 2012; Moniruzzaman et al., 2012; Rahman and Alam, 2013), however, there has been no floristic study on Munshigonj Sadar Upazila. The main objectives of the present study are to explore, identify and document the angiosperms of Munshiganj Sadar Upazila. Corresponding author. Email: dr_oliur@yahoo.com


Introduction
Munshiganj Sadar, an administrative Upazila of Munshiganj district comprises an area of 160.79 sq.km., and is consisted of 9 administrative unions, namely Adhara, Bajra Jogini, Char Kewar, Char Siloi, Mahakali, Mollakandi, Panchasar, Rampal and Rekabi Bazar.The Upazila witnesses the same climatic condition as other parts of the district.The hot summer, the long rainy season and the pleasant spring-cum-winter are the main noticeable seasons prevailing in the locality.The temperature of the area fluctuates between 12.7˚C and 33.7˚C throughout the year.Monthly average relative humidity varies from 62 to 83%, and monthly rainfall ranges from 7.7 to 373.1 mm throughout the year (BBS, 2011).There are three types of soil in the adjoining areas of Munshiganj Sadar Upazila, viz., heavy clayey soil that prevails over the major part of the study area, light clayey soil which occupies the second position in the area, and heavy loamy soil prevails over small area.The Upazila presents diverse habitats including scrub jungles, homesteads, char lands, riparian, roadsides and wetlands.
Over the last few decades several attempts have been made on the floristic studies in Bangladesh, particularly in the forest and protected areas (Khan and Afza, 1968;Khan and Banu, 1972;Khan and Hassan, 1984;Rahman and Hassan, 1995;Rahman and Uddin, 1997;Uddin and Rahman, 1999;Khan and Huq, 2001;Uddin and Hassan, 2004;Tutul et al., 2009Tutul et al., , 2010;;Arefin et al., 2011;Uddin and Hassan, 2012).Studies on angiosperm flora in different Upazilas of Bangladesh are limited (Islam et al., 2009;Rahman et al., 2012;Moniruzzaman et al., 2012;Rahman and Alam, 2013), however, there has been no floristic study on Munshigonj Sadar Upazila.The main objectives of the present study are to explore, identify and document the angiosperms of Munshiganj Sadar Upazila.

Materials and Methods
The work is based on fresh materials collected from Sadar Upazila of Munshiganj district from May 2012 to April 2013 (Fig. 1).Plant specimens were collected from different areas within nine unions of the Upazila and processed using standard herbarium techniques (Hyland, 1972).Collected plant specimens were critically studied, examined and identified at the department of Botany, University of Dhaka.Identification was confirmed by experts, by comparing with herbarium specimens deposited both at Dhaka University Salar Khan Herbarium (DUSH) and Bangladesh National Herbarium (DACB), and by consulting standard floras and literature, viz., Hooker (1872Hooker ( -1897)), Prain (1903), Khan (1972Khan ( -1987)), Dassanayake andFosberg (1980-1985), Khan andRahman (1989-2002), Siddiqui et al. (2007), Ahmed et al. (2008aAhmed et al. ( ,b, 2009a,b,c,d) ,b,c,d) and Rashid andRahman (2011, 2012).The identified families are arranged according to Cronquist's system of plant classification (Cronquist, 1981), and the genera and species under each family are arranged in an alphabetical order.Each species is furnished with updated nomenclature, Bangla names (wherever available), habit, habitat, phenology, potential value, status of occurrence in the area and voucher specimens.Voucher specimens are deposited in DUSH.

Results and Discussion
Taxonomic study of angiosperm flora of Munshiganj Sadar Upazila has revealed a total of 240 angiosperm taxa under 186 genera and 68 families (Table 1).Among them Magnoliopsida (dicotyledons) is represented by 195 taxa belonging to 146 genera and 55 families, whereas Liliopsida (monocotyledons) having comparatively less representation, only 45 species under 40 genera and 13 families.The study has revealed that Magnoliopsida constitutes about 81% of the total, while Liliopsida constitutes 19% of the total angiosperm flora.In Magnoliopsida, Asteraceae appears as the largest family comprising 13 species under 13 genera followed by Euphorbiaceae, Moraceae, Fabaceae and Mimosaceae.In Liliopsida, Poaceae is the largest family with 23 species under 19 genera followed by Araceae, Arecaceae, Commelinaceae and Cyperaceae.In the study area the number of species in the families varies from 1 to 23.Out of 68 families recorded, each of 27 families is represented by a single species.Five largest genera of dicotyledons are Ficus (7 species), Amaranthus (4 species), Persicaria (4 species), Syzygium (4 species) and Ipomoea (3 species); while that of monocotyledons are Commelina, Echinochloa, Leptochloa and Brachiaria, each with 2 species.
Among the total flora herbs are represented by 141 taxa, shrubs by 26 and trees by 73.Out of 68 families recorded, 10 dominant families are Poaceae, Asteraceae, Euphorbiaceae, Moraceae, Fabaceae, Mimosaceae, Solanaceae, Myrtaceae, Malvaceae and Rubiaceae.The dominant families along with the number of species and genera are shown in Figure 2.These ten families comprise 105 species that represent about 44% of the total species identified.The remaining 58 families with a total 135 species represent 56% of the total.
Though the study area has a moderately rich resource of angiospermic flora, it witnesses some threats which might cause this resource to extinct.Observations and group discussion with local people during field works resulted in identifying some major threats which include urbanization, modern agriculture, lack of awareness, exotic plantation and river erosion.Therefore, efforts should be undertaken to safeguard the plants through ex situ and in situ approaches, public awareness should be built up, and protection of habitats of the species should be ensured.

Fig. 1 .
Fig. 1.Map of Munshiganj Sadar Upazila showing the sampling sites of different unions.