Poplar. - In ancient times, the public places of Rome were decorated with rows of this tree, whence it came to be called Arbor populi, as being a tree peculiarly appropriated to the people. But Bullet asserts that the Poplar has obtained its name from the constant motion of the leaves, which "are in a perpetual state of agitation, like the populace." Populus alba, the Silver-leafed Abele, is a tree well adapted for shade, in barren soils, where other trees will not succeed. The tree is very objectionable on rich and valuable land, as it is very exhausting to the soil, throwing up numerous suckers, and making itself quite too common. For a protective belt of trees, on the barren shores of Cape Cod, and other similar locations, it is highly valuable. On an avenue like the Mill Dam leading from Boston Brookline, no tree could be substituted that would flourish so well. This road is built with marsh mud and gravel, and raised so high above the marsh that the suckers will not interfere with the adjoining land. These long lines of Abeles are very beautiful, when the leaves are agitated by the wind, and the silvery white of the under side is more fully contrasted with the green of the upper side. Populus tremuliformis. - American Aspen, or Trembling Poplar. - This is a well-known, small, graceful tree of our forests, remarkable for the continual agitation of its leaves by the slightest breath of wind. It resembles the P. tremula, or Aspen Poplar, of Great Britain, in this respect, as well as in its general appearance • and to which Walter Scott alludes in his lines:

"O, woman ! in our hours of ease Uncertain, coy, and hard to please, And variable as the shade By the light quivering Aspen made; When pain or sickness rends the brow, A ministering angel thou."

The Weeping Poplar has been introduced from Europe, - probably a variety of P. tremula, - and is a desirable ornamental tree.

The Balm of Gilead and Lombardy Poplar were in great repute fifty years ago, but have had their day, and are generally rejected at the present time.*