154 LANDSCAPE GARDENING. 



caused by the annual scaling off of the outer bark. A 

 blight, however, attacks the leaves in the early summer, 

 which causes many of them to wither and fall off, but are 

 followed by perfect foliage again later in the season. As a 

 result of this disease the branches become weakened and are 

 easily broken off by wind and storm. It requires a moist 

 rich soil and some very beautiful specimens are found grow- 

 ing in river-bottom lands in many sections of the country. 



POPLARS. Very few, if any, of the poplars are of any 

 value for permanent growth. They are very rapid in 

 growth, easily transplanted, possessing many varying forms 

 and colors, and useful where immediate effect is desired. 



SILVER POPLAR OR ABELE (Populus alba). This very 

 rapid growing tree is especially conspicuous when the silvery 

 under-surface of the leaves are turned up by the wind. It 

 has the fault, however, of throwing up suckers from the 

 roots and is sometimes attacked by insects. To prevent the 

 suckers from gaining strength and becoming troublesome, 

 they should be pulled up, when the shoots separate from 

 the root, and not be cut off at the surface. If cut off at 

 the surface of the ground, the whole root system remains 

 perfect and the buds are ready to start again with renewed 

 vigor. 



BOLLEY'S SILVER POPLAR (P. alba, var. Bolleana). 

 This tree is of a more close and spiry growth than the last, 

 with leaves of a darker color above and equally silvery 

 beneath, and though not fully tested under all conditions 

 promises to be more valuable than the common Abele. 



BLACK POPLAR (P. nigra). A most rapid growing tree 

 of a pyramidal growth and dark green leaves. Trees started 

 from cuttings in 1874 are now more than 2J- feet in 

 diameter and 60 feet high. It has, however, developed a 



