xvi INTRODUCTION 



so desirable for street use and makes a fine uniform showing when many are planted 

 in a line. Fortunately the species is not yet largely used in America for clipping 

 into formal outlines as it is in Europe, although there are places here where it might 

 well be used as it is along the canal banks in Holland the sides next the water 

 being allowed to grow naturally and the half next the houses being sheared off. 

 The other two species from Europe now offered by American nurseries the Silver- 

 leaved Linden and the Large-leaved Linden are more desirable for use as indi- 

 vidual specimens for parks and lawns than for street planting. 



The Bolleana Poplar is another tree that should be more generally known. 

 It is a fastigiate variety of the Silver Poplar just as the Lombardy is of the Italian 

 Poplar. The habit of growth of Bolleana is a bit more spreading than the Lombardy 

 and the foliage is more striking because of the white under surfaces of the leaves. 

 While this variety has the faults of its family rapid growth and quick decline, 

 with some tendency to dying branches it is worth planting to a limited extent 

 in narrow streets and small home grounds where there is not room for spreading 

 trees. It also can be combined to great advantage with the Lombardy Poplar in 

 group plantings, and should be used occasionally to relieve the monotony of the 

 endless stretches of Carolina Poplars which are so generally overplanted. The 

 Bolleana Poplar is now offered by many nurseries, and it is an easy tree to grow 

 from cuttings. 



The Norway Maple has been planted so often and for so many years that 

 it has sprung up naturally in many regions. It is treated of at some length upon a 

 later page but should be mentioned in this connection as almost an ideal street tree 

 for residence sections. It tends to form heads too low and as a result should be care- 

 fully pruned up when young. Its dense foliage, symmetrical outline and moderate 

 size, as well as its freedom from enemies, help to make it a favorite in most cities. 

 The tendency now is to overplant it, for a city should always have some variety, 

 even in the shade trees along its streets. 



