bank brassicaceae coastal Crambe maritima Cruciferae Cuckmere Haven ecology England english gravel Great Britain habitat halophyte halophytic natural nature plant sea kale shingle stones summer Sussex cliff coastline landscape plants altitude buds cold flowers green hardy harsh high lichens low growing norway norwegian odd pink red resilient small strange unusual white biotype boulder bush canada color colour conifers environment foliage leaf leaves montane mountain rock Rockies Rocky Mountains shrub snow trees blue clouds field footpath grass hill hilltop meadow quality sky slope South Downs top wild algae barnacle beach biology chlorophyll coast creation kelp life marine ocean photosynthesis sand science sea seaweed shell shore shoreline slimy slippery tidal tide appearance broadleaved damp herbaceous large leafy marsh marshland moist muddy murky rain raindrops reeds stalks stems swamp swampland swampy vegetation water watery wet wetland abundance abundant clover diverse diversity flora hills profusion rich umbellifer verdant