Herbarium of bryophytes (KRAM-B) at the Institute of Botany PAS is the largest collection of these plants in Poland. In 2018 these collections exceeded the number of 243 575 incorporated and numbered specimens (60 thousand of specimens are waiting for the development and incorporation into the main collection). The size of the herbarium collection ranks in the top twenty largest herbarium collections of bryophytes in the world. In addition, herbarium has the world's largest collection of mosses and liverworts from the polar regions of southern hemisphere, including a unique collection from Crozet Islands, Kerguelen Islands, Prince Edward Island, South Georgia, Macquarie Island, Gough, Amsterdam, Tristan da Cunha, as well as significant collections of mosses from tropical Africa and southern part of South America and Australia. They were largely collected by employees of the Laboratory of Bryology during various expeditions. Herbarium also has over 2,000 of nomenclatural types, i.e., specimens that were used to describe the new species, varieties and forms of bryophytes. These are the most valuable collections, determining the status of the herbarium as unique compared to other similar collections. Herbarium has almost all historical collections of bryophytes from the Polish territory since the beginning of the nineteenth century (the oldest Polish collections of bryophytes from Łobarzewski and Rehmann from years 1840 to 1860 and later all major Polish collections from the nineteenth and twentieth centuries, such as collections of J. Krupa, I. Szyszyłowicz, T. Chałubiński, M. Raciborski, A. Żmuda, B. Szafran, M. Kuc), which means that any studies on these plants in our country cannot be implemented without comparison with the collection. Herbarium has an active exchange of collection with all the most important bryophytes herbaria in the world. Hence, there are complete collections of bryophytes from all continents. In total there are about 80% of all known species of mosses and liverworts representing approximately 95% of all types of plants in the world.

At the Herbarium of Bryophytes 4 series of herbarium publications are issued, including domestic and exotic bryophytes:

Musci Poloniae Exsiccati (R. Ochyra, H. Bednarek-Ochyra)
Bryophyta Antarctica Exsiccata (R. Ochyra)
Bryophyta Svalbardensia Exsiccata (H. Bednarek-Ochyra, B. Godzik, K. Grodzińska)
Bryophyta Africana Selecta (R. Ochyra, T. Pócs)