Six rare mosses and one hepatic were grown in in vitro culture at the Conservatoire et Jardin Botaniques, Geneva. All seven rare Swiss bryophytes figure on the Swiss Red List of bryophytes under the categories VU, CR and EN. This was the first time that any of these species was cultured under in vitro conditions. They were grown to establish the protocols necessary to create and maintain live collections of each species in vitro as a method of ex situ conservation, in an attempt to understand their species biology and to try to ascertain the reasons for their rarity in the wild. The specimens were sent by Nationale Inventar der Schweizer Moosflora (NISM) for culturing. The majority of the specimens received were of Tayloria rudolphiana and therefore the study focused on this species particular biology. Axenic cultures were obtained of Bryum versicolor, T. rudolphiana and Tetraplodon urceolatus on Parker's medium and Parker's and MS medium respectively. A non-axenic culture was obtained of Riccia breidleri. Fissidens grandifrons, Pottia heimii and Ulota rehamnii did not establish on Parker's medium. In vitro culturing proved to be a good method which allowed the close study of all the specimens which regenerated in culture and for those that did not regenerate, which culture conditions are unsuitable for those species. It specifically allowed the observation of brood cells for the first time in T. rudolphiana. It was also established that growth is not a factor of T. rudolphiana's rarity as it grew abundantly on a variety of media and that it is therefore not an obligate nitrophile; that it is not wind-dispersed as stated in literature, but most likely dispersed by insects or epizoicly due to the characteristics of its spore capsules and the presence of ‘sticky spores'; and that its rarity is as a result of its specific habitat requirements and poor dispersal capability.