AbstractChawley Brick Pit, Oxford fell into disuse in 1935 and provided a variety of habitats which Were exceptional for the district, especially on wet sand and clay, in which many locally rare species of bryophyte appeared. By 1948 it had a rich bryophyte flora which was still being added to by new immigrants, many of which must have come from at least 30–60 km distance. Between 1966 and 1985 the development of woodland and the natural evolution of the soil had eliminated most of these early immigrants but some other equally remarkable shade-tolerant species had arrived. About half of the hepatic species must have come as spores, and the other half either as, spores or gemmae. Many of the immigrant mosses are dioecious and fruit rarely but spores, nevertheless, seem the most likely means of introduction for most of them.