bank brassicaceae cliff coastline Crambe maritima Cruciferae Cuckmere Haven ecology England english gravel Great Britain habitat halophyte halophytic landscape natural nature plants sea kale shingle summer 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 plant rock Rockies Rocky Mountains shrub snow trees blue clouds field footpath grass hill hilltop meadow quality sky slope South Downs Sussex top wild algae barnacle beach biology chlorophyll coast coastal creation kelp life marine ocean photosynthesis sand science sea seaweed shell shore shoreline slimy slippery tidal tide stones 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