Brazilian naturalist João Barbosa Rodrigues became director of JBRJ in 1890, and his wide experience, knowledge and passion were fundamental to increase the research activities of the institution. Within the same year he founded the library and the botanical museum, as well as the Rio de Janeiro Botanical Gardens Herbarium (RB), with an initial collection of 25 thousand specimens gifted by the Brazilian Emperor, D. Pedro II. Barbosa Rodrigues' tenure was to last nearly 20 years, and during this time he created the post of "travelling naturalist", for which he employed qualified professionals in charge of collecting plants throughout the country, augmenting JBRJ's scientific collections.
The RB Herbarium collection continued to grow through the XX century, with the oustanding contributions of several eminent botanists, such as Adolpho Ducke, Johan Löfgren, João Geraldo Kuhlmann, Paulo Campos Porto and Alexander Curt Brade. Scientific expeditions to diverse areas of Brazil and exchange programmes with national and foreign institutes were intensified, enhancing the collections and increasing the scientific significance of JBRJ for the study of the Brazilian Flora.
A center-piece of the research carried out at JBRJ, the Herbarium RB is one of the largest botanical collections in Brazil, being constantly under study by both Brazilian and foreign researchers interested in Neotropical Botany as well as other related subjects. School and university students also visit RB to learn about the importance of biological collections in such a biodiverse country.
RB is organized by taxonomic groups and houses collections of Algae, Fungi, Bryophytes, Ferns and Lycophytes, Gymnosperms and Angiosperms. As well as pressed and dried specimens there are ancillary collections including wood, carpological, photographs, DNA bank, etnobotanical and spirit collection, adding up to nearly 600 thousand items. Amongst these, the most important specimens are the nomenclatural types, nearing 12 thousand images already available online in the JSTOR site. Collection digitisation started in 2005 and the general public can consult it through the JBRJ site . From March 2012, the JBRJ, as part of the REFLORA/CNPq Programme, started the complete image capture of its collections. The next challenge will be to include microscope slides from the wood collection, and also the Bryophyte, Fungi and Lichen collections.