The herbarium of the Department of Botany and Zology of the Masaryk University, Brno, is registered in the Index Herbariorum under the acronym BRNU. It was established in 1921 when private herbaria of Prof. Josef Podpěra and Prof. Heinrich Laus (Olomouc) were fused. Using his long-time experience with the exchange of herbarium specimens and contacts with numerous botanists, Podpěra acquired numerous herbarium specimens from abroad. At the end of 1921, the herbarium already contained 31 986 specimens.
The herbarium grew most rapidly before World War II, and above all during the first decade of its existence. Since the late 1940's, the annual increase in specimen number has been 3500–4000. Apart from the collecting activities of the staff, herbarium specimens were acquired in different ways. Initially, Prof. Podpěra was able to get financial support from the governmental sources, and for this money collections were purchased from private persons and botanical institutions. These acquisitions include for example Dörfler's Herbarium normale and Kneucker's Cyperaceae (excl. Carices) et Juncaceae exsiccatae, as well as the personal herbaria of František Maloch and Franz Petrak. In 1925, the herbarium of the German Brno Natural History Society (Naturforschender Verein in Brünn) was purchased. The institute further acquired, partly as inheritance or gift, lifelong collections of amateur botanists Karel Rothe, František Polášek, Václav Spitzner, Josef Vitoušek and Johann Wiesbauer.
Essential for the growth of the Herbarium by exchange was the exsiccate series Flora exsiccata Reipublicae Bohemicae Slovenicae. Centuriae I–XIII were issued before World War II almost every year in 1925, 1926, 1928, 1929, 1930, 1931, 1932, 1933, 1934, 1935, 1936, 1937, and 1938. After 1945, the financial support for this purpose was substantially reduced. However, due to the personal efforts of Prof. Miroslav Smejkal, curator of the herbarium, another four centuriae (XIV–XVII) were issued in 1957, 1965, 1972, and 1978, preceded by a separate centuria of mosses in 1947. Due to the exchange of this exsiccate series, the Herbarium obtained many specimens from various European and World botanical institutions.
After World War II, some other large inheritances were incorporated into the herbarium, including personal herbaria of František Čouka and Anton Fröhlich. At the same time, staff members of the department, among them namely Miroslav Smejkal, Jiří Vicherek, Anežka Hrabětová, and František Dvořák, collected many herbarium specimens in numerous field trips to sites in the former Czechoslovakia and abroad. Since 1965, many specimens have been gathered by students as part of master theses on local floras.
In December 2008, the herbarium contains more than 597,000 specimens, among them 507,000 sheets of vascular plants, 58,000 specimens of bryophytes, 15,000 specimens fungi, 15,000 specimens of lichens, and 2,000 specimens of algae. It is the fourth largest herbarium in the Czech Republic (after the herbaria of the Department of Botany, Charles University in Prague [PRC], of the Department of Botany of the National Museum in Prague [PR], and of the Moravian Museum in Brno [BRNM]). However, the number of specimens of the Czech and Moravian flora is approximately equal in all the four herbaria.
The collection of type specimens includes mainly taxa published by the former and present members of the department, i.e. A. Hrabětová-Uhrová (Crataegus and Cotoneaster), M. Smejkal (Epilobium), and M. Dvořáková (Minuartia). Further, there are numerous type specimens of taxa described by J. Podpěra (many infraspecific taxa published in three volumes of the Flora of Moravia) and F. Dvořák, together with isotypes of taxa published, e.g., on the labels of the Gerbarij Flory SSSR exsiccate series, inserted in the main collection.
The arrangements of the flowerings plants follows the Engler system, based on the genus numbers after K. W. Dalla Torre's & H. Harms' Genera Siphonogamarum, ad systema Englerianum conscripta (1900–1907). Genera Siphonogamarum, ad systema Englerianum conscripta; species within genera are arranged alphabetically. Pteridophytes and mosses are arranged alphabetically, as well.