Farthing Downs is a long strip of grassland with pockets of ancient woodland, which narrows to a point at the northern end. It is the most extensive area of semi-natural downland left in Greater London. Its chalk and natural grasslands have a large variety of rare herbs, including some which are nationally scarce, such as the wildflower greater yellow-rattle. This is specially protected by legislation and Farthing Downs and Happy Valley have the major part of the British population.