The origin of the Herbarium's collections dates back to 1872 under the direction of Giuseppe De Notaris (1805-1877), one of the leading authorities in the field of cryptogamy (*), who hold the Chair of Botany at the University.
At that time, the Institute of Botany had few rooms inside the ancient convent of San Lorenzo in Panisperna. In these rooms De Notaris set up his very rich library and his important cryptogamic collection, actively dedicating himself to the acquisition of pre-existing collections, such as the Herbarium Ettore Rolli (1818-1876), and contributing with his personal collections. Precisely to enrich the Herbarium that was being established, De Notaris returned to the study of phanerogams (*), which had been abandoned for a long time.
When De Notaris died, five years after his arrival in Rome, he was succeeded by Nicola Antonio Pedicino (1839-1883). Under his direction several collections were acquired, such as those of Pietro Sanguinetti (1802-1868), Elisabetta Fiorini Mazzanti (1799-1879) and the prestigious cryptogamic herbarium of De Notaris.
On occasion of the premature passing away of Pedicino in 1883, Pietro Romualdo Pirotta (1853-1936), Professor of Botany at the University of Modena, was called to succeed him. We owe the construction of the first Institute of Botany, in the garden of Panisperna, to the letter. The Institute was already active in the academic year 1889-90. The Herbarium was finally able to have adequate rooms and become regularly functioning thanks to the efforts of the first conservators: Achille Terracciano from 1887, Emilio Chiovenda from 1896 and Fabrizio Cortesi from 1904. The number of specimens of the Herbarium was considerably increased with the collections of Pirotta himself, his students and the staff of the Institute. An intense exchange activity with Italian and foreign botanical institutes and with numerous scholars dates from this period. Various herbaria were also purchased, the most important of which is that of Vincenzo Cesati. Pirotta was responsible for the foundation, in 1904, of the Colonial Herbarium Collection, destined to house the abundant materials coming from the Italian colonies of Eritrea and Somalia. But when in 1913 the National Herbarium in Florence was planned at the Botanical Institute, to include the flora of all the Italian colonies, Pirotta, convinced of the usefulness of this initiative, spontaneously gave up the entire Colonial Herbarium (1914).
The current arrangement of the Herbarium dates back to 1938, the year in which the final move of the collections to the rooms of the Botanical Institute of the University Campus took place.
In the years 2006-2007, with the funds granted for the celebration of the VII centenary of "La Sapienza" University, it was possible to implement a conservative air conditioning system for the two rooms intended to house the collections. The furnishings of all three rooms of the Museum have also been completed and modernized.
Currently the Herbarium Museum consists of numerous historical and contemporary collections, whose overall consistency is estimated at more than one million specimens, which places it among the main herbariums in Italy and Europe.
It is included in the Index Herbariorum, an international network of herbaria, where it is indicated by the acronym RO.
(*) The traditional term "phanerogams" indicates the groups of seed plants, i.e. gymnosperms and angiosperms; the term "cryptogams" indicates all seedless groups, i.e. algae, lichens, bryophytes, pteridophytes and fungi.