Angiospermic flora of Gazipur district, Bangladesh

Abstract

1. A total of 833 taxa under 489 genera and 126 families have been recorded from the area of Gazipur district. Among the taxa recorded, the number of taxa under Magnoliopsida and Liliopsida are 605 and 228 respectively. Magnoliopsida consists of 98 families and 369 genera, while Liliopsida consists of 28 families and 120 genera. This is the outcome of 40 trips in 95 localities of the district covering forest areas, plain land, village thickets and wet lands, as well as herbarium specimens and relevant literature survey. 2. The families have been arranged according to Cronquist’s system of classification (1981). 3. Dichotomous bracketed keys to the families, genera and species have been provided. The genera and species have been arranged alphabetically under each family. 4. Original citation of each taxon with valid name and important synonyms, local name and English name (when available), brief description, chromosome number, flowering and fruiting time, ecological notes, distribution, uses and specimen examined have been provided. 5. Habitat, duration of life-span, phenology, status of occurrence, economical importance of the species and also locations are provided. Exotic taxa are specified as well. 6. Of the total number of taxa, herbs are represented by the highest number (463= 55.58%), followed by trees (174= 20.89%), shrubs (116= 13.93%), climbers (75= 9.0%), epiphytes and parasites taxa constitutes less than 1% of the total angiospermic flora. 7. The phenology of the species shows much seasonal overlapping. In the rainy season 380 species produce flowers/ fruits, in winter 367 species produce flowers/ fruits, while 86 species produce flowers/ fruits throughout the year. 8. Out of 833 angiospermic taxa recorded, 160 species (19.23%) appear to be exotic, of which 48 are trees, 30 shrubs and 82 herbs including climbers. 9. Of the recorded taxa, 766 appear to be important from ecological and/ or economic point of view. 10. In the study area the following species have been recorded only once and hence considered as rare in the area: Ecbolium ligustrinum (Vahl) Vollesen (Acanthaceae), Entada rheedii Spreng. (Mimosaceae), Hygrophila schulli (Buch.- Ham.) M. R. & S. N. Almeida (Acanthaceae), Leea alata Edge. (Leeaceae), Pterospermum semisagittatum Buch.-Ham. ex Roxb. (Sterculiaceae) and Strobilanthes scaber Nees (Acanthaceae). On the other hand the following species have been recorded from most of the localities visited and hence considered common in the study area, such as Amaranthus viridis L. (Amaranthaceae), Calotropis procera (L.) R. Br. (Asclepiadaceae), Centella asiatica (L.) Urban (Apiaceae), Chenopodium album L. (Chenopodiaceae), Cleome rutidosperma DC. (Capparaceae), Eclipta alba (L.) Hassk. (Asteraceae), Nelsonia canescens (Lamk.) Spreng. (Acanthaceae), Ricinus communis L. (Euphorbiaceae), Shorea robusta Roxb. ex Gaertn. f. (Dipterocarpaceae) and Synedrella nodiflora (L.) Gaertn. (Asteraceae). 11. Ethnobotanical information collected from local people, specially from people belonging to Koch, Garo and Santal communities, are also provided. 12. The study has identified threats to the plant diversity of the district and has proposed some measures for their conservation.