FOREST TREES. 189 



FOREIGN SPECIES A]*D VARIETIES. 



I do not know of any species or varieties of the exotic Pop- 

 lars, that are of any economic value, although there are a few 

 worthy of cultivation as ornamental trees. The two foreign 

 species best known in this country, are : 



Pop ul us alba. Abele Tree, or Silver Poplar. A large, rapid- 

 growing tree, native of Europe, with large-lobed leaves, green 

 above and silvery white beneath. A rather handsome tree, but 

 p. decided nuisance, owing to the great abundance of suckers, 

 which come up almost constantly from the roots. There are 

 several varieties of this species, but all have the same habit, 

 and for this reason are not to be recommended, except for 

 planting in locations where the suckers will not interfere with 

 the growth of other kinds of plants. If grafted on stocks of 

 species that do not throw up suckers, the Silver-leaved Poplars 

 might be admitted into grounds of limited extent. 



P. ilila t atii . or fasti .riata. Lombardy Poplar. A century ago this 

 was a favorite tree for planting near churches, cemeteries, and 

 dwellings, but of late it is seldom employed, except to give 

 variety of form in arranging the trees planted in large parka 

 and pleasure grounds. 



P. nlgra. European Black Poplar. Has wide, spreading 

 branches, with very large leaves, and very sticky or glutinous 

 buds. 



P. snaveolens. This species is from Central Asia, and was in- 

 troduced by Dr. Regel, director of the Imperial Gardens at St. 

 Petersburg, Russia. It possesses a very agreeable aromatic 

 odor ; hence the specific name. This is very evident when the 

 buds are rubbed between one's fingers. 



There is a handsome weeping variety of this (P. nigra pendu- 

 Id), that is propagated by grafting high upon strong stocks of 

 some erect young species. In addition I may name the Weep- 

 ing Grecian Poplar (P. grceca pendula). The Curled-leaved 

 Poplar (P. crispa). Several additional species and varieties 

 have been introduced from Europe and Asia, and may be 

 found described in nurserymen's catalogues. 



PROSOPIS, Linn. Mesquit, Screw Sean. 



A genus of nearly twenty species of tropical-evergreen, 

 spiny trees, closely allied to the acacias, having pinnate leaves, 

 pea-shaped flowers, and fruit a bean-like pod, containing sev- 



