For political and geographical reasons, Bhutan has until very recently remained inaccessible to most botanists from the outside world, and no comprehensive Flora of the country has ever been written. From 1914 onwards, however, a small number of privileged botanists and horticulturists, mostly British, were able to travel extensively in Bhutan and bring back to Britain large plant collections. The greatest of these collectors were undoubtedly Frank Ludlow and George Sherriff who made seven visits to Bhutan between 1933 and 1950 and amassed over 6000 herbarium specimens as well as large numbers of living plants and seeds. In spite of the considerable collecting activity, almost none of the resulting information has been available to those in Bhutan, such as the forestry department for whom the Flora of British India remains the only reference work. In response to this, the Royal Government of Bhutan commissioned production of this flora which by was completed in 2002.