Black poplar  (Populus nigra)

Black poplar, thought to be Britain's most endangered native timber tree (2), has a wide, rounded crown and dark grey fissured bark, with many swellings ('bosses') on the trunk (1). The deep green leaves are roughly triangular or oval in shape and become yellow in autumn (3). The flowers occur on 3-5cm long catkins (1), and male and female flowers are produced on separate trees; male flowers have red anthers and female flowers have green stigmas (1). Old specimens often develop an obvious lean (8), and older branches are frequently pendulous (9).