downland England english Great Britain green hill landscape natural nature summer Surrey view cloud field meadow plants sky South Downs spring Sussex chalk flower flowers papaver plant poppies poppy red wild countryside crops farm fields hills national park road rolling autumn crop cumulus down Downs shadow uk junction village wood footpath hike path rural track trail Trek walk Buckinghamshire Chiltern Hills escarpment grassland Natural landscape plain bedstraw carpet ecology flora Galium lady's bedstraw native summer flowers umbellifer wild flowers