Phanerograms section is one of the important sections of NHPL which conduct research activities manly on flowering plants viz. Angiosperms and Gymnosperms from different parts of the country. Herbarium specimens are collected plant specimens pressed, dried, mounted, identified and arranged according to accepted system of nomenclature. Herbariums are national treasure and reference material for plant research. About 1,60,000 herbarium specimens and 83 type specimens are arranged according to Bentham & Hooker's system of classification for family, genus and species are arranged alphabetically. There are more than 20,000 indentified plant specimens ready for mounting and housing and more previously collected plant specimens are in the process of identification, mounting and housing.
In 1976, Catalogue of Nepalese Vascular Plants had been published and then three Volumes (Catalogue of Nepalese Flowering Plants Vol-1,2,3) in 2010, 2011 and 2012 respectively; have been published which includes the brief information about distribution of plant species preserved in the Herbarium.In 2015, Catalogue of Nepalese Flowering Plants Supplement 1 has been published. It is estimated that about 6,500 species of flowering plants are found in Nepal. Among them, about 82% (4,543) of flowering plants are preserved in this section.