ASPEN, or TREMULOUS POPLAR, Populus tremula (see PoprAR). A tree which grows plen tifully in Europe and in Siberia. It is a native of Great Britain, and is frequent in Scotland, where it is found even at an elevation of 1500 feet above the sea. It has received the specific name trcmula, from the readiness with which its leaves are thrown into a tremulous motion by the slightest breath of wind—a property for which, indeed, the aspen leaf has become proverbial. The leaves are nearly orbicular, but are broadly toothed, so as almost to exhibit angles. The footstalks are compressed, and in part to this compression is due the sensitiveness of the leaves to the breeze. The aspen grows quickly, with a straight stein, reaching to a height of from 50 to 80, or even 100 teet. In unfavor able situations it becomes dwarfish. The wood is snft, porous, light. white, and smooth; it tbtes not make good fuel, but is very fit for the turn ing lathe, and especially for manufacture of troughs, trays, pails, etc. It is deemed excellent for arrows. If the stein is peeled and allowed to dry before it has been cut down, the wood be comes harder, and it may then be used as timber for the interior of houses. On this account the
tree is of great importance in many districts, the more so as it succeeds in any soil, although it prefers one that is moist and gravelly. The hark contains considerable quantities of the glu coside called salicin. The charcoal made from the tree is sometimes used in the manufacture of gunpowder. I'opvins tremuloides, a similar species (according to some, a mere variety of the ordinary aspen), is a native of North America, and is called the American aspen. This is one of the •idest-distributed trees of North Amer ica. It is found in Labrador and Alaska, and again as far south as Pennsylvania, Missouri, and even New Mexico. It lives in California also. Very similar also is another North American species, Pointlus gramlidentata, which has a more restricted range. The wood of both these. species is extensively used in the United States for the manufacture of wood pulp. Popu lus grandidentata has given rise to a number of forms with pendulous branches that are exten sively grown as ornamentals. See also POI'LARS.