Synopsis Nepal with an area of 1,47,181 sq. km. and population of over 18.4 million has about 6,500 species of flowering plants of which more than 700 species are medicinal and 315 species of endemic plants. The country is reasonably rich in plant diversity which constitutes one of the most valuable renevable natural resources. Earlier floras were most remarkable botanical work of reference but were mainly devoted to the plants of high altitudes. The plains of eastern Nepal is floristically coast explored in the past. Further the area is facing threats to its natural vegetation due to rapid unplanned industrialization and urbanization. The present flora is based on four yield of intensive and extensive study of the plants of plains of eastern Nepal in the field, laboratory and herbarium. The flora deals with sytematic analysis of 743 species under 493 genera & 128 families of flowering plants both wild and naturalised.