The abele is more common in Scotland than in England, and many large trees might be mentioned in the North. It would be difficult, however, to find any to surpass two growing at Mauldslie Castle, in Clydesdale, one of which in 1911 measured 100 feet high and 21 feet 3 inches in girth, the other 117 feet by 16 feet 5 inches. It should be noted that the girth of both was taken at between 2 and 3 feet from the ground, instead of 5 feet, which is the proper height for measurement.
Next in economic importance to the grey poplar stands what is popularly known in this country as the black Italian poplar (P. serotina), which is not Italian in any sense, but a hybrid originating in France (where it is called peuplier suisse) between an American species and the true black poplar (P. nigra). This confusion of names is all the more perplexing because the upright variety of the true black poplar goes by the name of Lombardy poplar. However, one must use the names most generally recognised among woodmen, and the black Italian poplar is well worthy of more attention than it has hitherto received in this country, for it produces valuable timber in greater bulk in a short term of years than any other British-grown tree. Mr. Elwes has recorded how thirty poplars of this variety, planted on cold clay in Gloucestershire, not worth 5s. an acre, were sold for £3 apiece at forty-eight years of age. He lays stress on the importance of giving this tree plenty of room at all stages of growth, planting them at 15 to 20 feet apart, for the timber is little worth unless the tree gets enough light to enable it to produce wood rapidly. This precept applies to every species of poplar.
The tallest black Italian poplar in Great Britain is probably one growing on the banks of the Tillingbourne, in Albury Park, Surrey, which in 1912 measured 150 feet high, with a girth of 15 feet 3 inches. There are many fine specimens in Scotland, notably one at Scone Palace, which in 1904 was 132 feet high, with a girth of 15 feet 4 inches. Another at Monzie, in Perthshire, measured at the same time, stood 125 feet high.
Turning now to the true black poplar (Populus nigra), we find that this species, a native of Midland England, but probably not of Scotland, has become established in the eastern United States, having been introduced there by British colonists. It has often been confused with the black Italian variety, but may easily be distinguished in this country by the large burrs on the trunk, by its earlier leafing, and by the young foliage being green, instead of reddish, as in the black Italian. The true black poplar also sheds its leaves much earlier in autumn than does the other. It is not a tree commonly planted in Scotland, but there are specimens ranging from 90 to 100 feet high at Dalzell, Ross, and Cambusnethan, in Lanarkshire; at Auchentorlie, on the Clyde; and at Smeaton-Hepburn, in East Lothian.
The variety of this tree so well known as the Lombardy poplar forms a notable feature in the landscapes of Southern England, Central and Southern Europe, and a great part of Asia. As it can only be propagated by cuttings, it is believed that all the millions of Lombardy poplars spread over the continents of Europe and Asia originated with a single "sport" growing on the bank of the river Po early in the eighteenth century. Probably the first of its race was brought to England about 1750 by the third Duke of Argyll, and planted by him at Whitton, near Hounslow. This tree, which has now disappeared, was measured by Loudon before 1838 as 115 feet high.
WHITE POPLAR (Populus alba) In July
WHITE POPLAR (Populus alba) In December
One peculiarity of the Lombardy poplar I do not remember to have seen noticed by any writer on forestry. Other poplars of all sorts, including the black poplar whereof this is only a variety, mingle branches freely with their neighbours; but the Lombardy poplar is a regular Sainte-Nitouche, and will not suffer contact with any other tree, even one of its own race. A curious example of this may be seen in London. When the Buckingham Palace Hotel was built, somewhere about 1860, Queen Victoria desired that a screen of trees should be planted within the Palace enclosure to shut the hotel out of view. The Office of Works chose the Lombardy poplar, calculating that it would form a lofty, thick hedge. Not a bit of it! The trees died rather than touch each other; they have been replaced times without number; but the Office of Works has never discerned the secret of their temperament, and continue their task of Sisyphus year after year, filling the gaps caused by death with trees of the same kind. Had a row of true planes been set there at first, the privacy of the Palace would have been secured long before this.