This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
It is an easy step from the Willows to the Poplars, for the Genus Salix and the Genus Populus together form the Order Salicineae. We have only two indigenous species in Britain - the White Poplar or Abele (P. alba), and the Aspen (P. tremula). In spite of the fact that it was not introduced until 1758 it may safely be said that the Lombardy Poplar is now a better known tree than either of our native species. It is the tree that is so frequently planted as a live screen, to break the force of the wind or to hide some undesirable prospect. Its growth is most rapid, and the story is told of a man who planted this tree in his garden at Great Tew, in Oxfordshire, and was living fifty years after, by which time his tree had beaten him considerably in the matter of growth, being then a hundred and twenty-five feet high! But like most other trees of rapid growth it attains no great age - for a tree, that is - and it is doubtful if it exceeds a century of life. The whole of its branches and shoots take an upward direction, which gives the tree the fastigiate or sharp-pointed outline which has suggested its specific name.
In our native Poplars the shoots are downy;in fastigiata they are smooth. The leaves are borne on long compressed stalks, which give them the ever-tremulous movement so well known in connection with the Aspen. As in the Willows, the sexes are on separate trees, and the flowers all in catkins. There is no perianth, a single bract-like scale serving instead, though there is a cup-shaped organ, within which is found, in one plant, a one-celled ovary, and in the other sex from twelve to twenty stamens with red anthers are attached to the under-side of the cup.
Lombardy Poplar. Populus fastigiata. - Salicineae.
The name of the genus Populus is the old Latin for Poplar and Aspen.