 The black poplar is also a different species from the more widespread black Italian poplar ("Populus" x "euramericana" or "Populus" x "canadensi"s) which is a hybrid between the black poplar and the North American eastern cottonwood ("Populus deltoides").Poplars are unusual in that there are separate male and female trees.Male black poplars are far more numerous than female trees in Britain and seedlings are, therefore, very rare.