Betula Nigra - Summer Cascade AKA River Birch Feathered Tree XL 300/350cm 45 Litre: A relatively new cultivar of River Birch a graceful quick growing tree renowned for its amazing constantly peeling bark ( pictures 2, 3 and 4 ). Foliage is dark-green with subtle catkins throughout spring and summer but takes on a striking yellow colour in autumn. Betula Nigra can be planted in most locations and does particularly well in wet sites preferably in acidic soil, although this is not a necessity.