Introduction

In the eight years since M. C. F. Proctor's paper, ‘A Bryophyte Flora of Cambridgeshire’ (Proctor, 1956) went to press, knowledge of the bryophytes of the county has been considerably extended. About 30 additions have been made to the county list, and the frequency and distribution within the county of many species is now better known. For several species, the first record for the county has been put back over 50 years, by the finding of Cambridgeshire specimens in F. Y. Brocas's collection at Saffron Walden Museum, and through the correction of faulty identifications of specimens in the Cambridge University Herbarium. A few published records have been omitted when there is doubt about the identity of the plants. A start has been made with the recording of bryophytes within 10 km. squares of the National Grid, and this has led to collecting in new areas, with some unexpected finds. Details of the habitat, locality, collector and date for these records have been deposited in the library of the Botany School. I am particularly indebted to Mr P. J. Bourne, who has made numerous excursions to all parts of the county in search of bryophytes. His collecting has led to over 600 additions to the 10 km. square lists. Others who have helped are acknowledged on p. xiii.