POPLAR, a genus (Populus) of trees of the family Salicacece which includes only one other genus, Solix, the willows. The species, which probably do not exceed 25, are widely distributed in the Northern hemisphere from sub-tropical regions to the limits of vegetation both in latitude and altitude. Half of them are American. They are mostly of small or medium size, quick growth and short duration; bear deciduous, broad, heart-shaped or lozenge shaped leaves on long slender petioles; dicecious, naked flowers usually in pendulous catkins which appear before the leaves; and small two to four-celled fruits (capsules) filled with cot tony seeds. Their wood is generally soft, light and white. It is little used for timber or lum ber; but it is an important fuel wood in regions such as the Western States, where fuel is scarce and costly. The trees are often planted for this purpose and for windbreaks, their rapid growth being in their favor. They are also favorites for copses and for pollarding (q.v.). The lumber called poplar is generally that of another tree,— the whitewood or tulip tree Poplars are used in enormous quan tities for making wood-pulp paper, carboard, etc., especially in Ontario, Quebec and the New England States, where hundreds of acres of forest are cut for this purpose annually. As ornamental trees they are frequently planted to excess at summer resorts because they quickly make an effect. In such cases they give an air of cheapness to the place not observable where maples, oaks, etc., are prevalent. The latter should always be planted with poplars, in order to replace them.
Poplars are as easily propagated from cut tings as currants or willows; in some cases the switches need only be stuck in moist ground. The choice horticultural varieties, especially the weeping kinds, are grafted. Suckers may be used, but since their removal generally induces the growth of many more suckers, this method must be practised with caution except where the ground is not valuable. The species will succeed in a great variety of soils from sand to clay, and in almost any situation, even in crev ices on rocky mountain slopes. Some of them, however, especially the cottonwood, seem to thrive best in low alluvial land upon the mar gins of streams.
The best-known species are probably the. following: The Lombardy poplar (P. nigra, var. italica, also called P. pyramidalis, P. italics, P. fustigiata, etc.) is probably a native of Asia, whence it has spread to the Mediterranean re gion and thence to temperate countries through out the world. It is noted for its erect instead of spreading habit, which makes it a striking specimen in ornamental plantings. It grows very rapidly, attains a height of 100 to 150 feet, but is not long-lived in the coldest States and most of Canada. It is one of the worst species to produce suckers; hence it should not be planted where the soil will be disturbed by cul tivation.
The black poplar (P. nigra) is a native of northern Asia and Europe, and is occasionally seen as an escape in America east of the Mis sissippi River. It is of rather pyramidal habit,
less erect, however, than its variety the Lom bardy, and of darker colored foliage and slower growth than the cottonwood. It seldom ex ceeds 100 feet in height. The down from its seeds has been used for paper, hat and cloth making in France, but the industry has been abandoned as unremunerative. The wood, which is not prone to shrink and swell, is used for turning, cabinet-making, toys, flooring, doors, etc.
The Carolina poplar (P. deltoides) is an American species well known from New Brunswick to the Rocky Mountains and south ward to the Gulf States. It is the largest of the genus, specimens sometimes attaining 150 feet in height and more than six feet in diam eter. It is also one of the most valuable, its timber being considered useful for nearly all the purposes mentioned. It is also more highly prized for ornamental planting than any other species, since it not only succeeds well in all soils, but possesses qualities of stability and strength lacking in other species. Its bright, glossy foliage, constantly in motion, adds cheeriness and life to plantations as few other trees can. It is one of the most popularly planted species in the Western States, not only for shelter and for fuel but for timber and lum ber. In Europe it is often called the Canadian or Italian poplar. It has several horticultural varieties, among which a striking form .s the golden-leaved P. vangeertii, which is one of the choicest of yellow-leaved trees.
The balsam-poplar or tacamahac (P. balsam ifera) is indigenous from Newfoundland to British Columbia and extends well into Siberia, its southern limits, except in the mountains, being about Pennsylvania. Its erect growth re sembles the Lombardy poplar, but it is slower in growth, more rugged and hardy. The type species and its three well-marked botanical vari eties exceed the cottonwood in variability. A closely related species is the balm of Gilead (P. candicans), a well-known tree, frequently planted, with large buds noted for their spring fragrance. It is indigenous from Nova Scotia to New Jersey and westward to Minnesota, and is less pyramidal than the type species, usually making a rather broad top. It seems to be dis appearing from the woods, though formerly it was a large tree sought for its timber. For the dark tone of its foliage it is often planted as a background tree, but not in smoky localities.
The white poplar or abele (P. alba), a European and Asiatic species, which grows about 75 feet tall, has been introduced into America, where it has become naturalized, from Nova Scotia to New Jersey. In Europe it is used for many of the purposes mentioned above. The European aspen (P. tremula), common in both Asia and Europe, is known in America mainly by its weeping variety (P. tremula, var. pendula). The American aspen (P. tremuloides) is one of the first trees to ap pear in clearings, thus acting as an important agent in reforestation, holding the soil until slower-growing trees can obtain a start. (See