SPECIES FOR STREET-PLANTING 35 



young it is of pyramidal form and eventually becomes a 

 large, round-headed tree. Its foliage is of light green color, 

 very large and abundant, and produces a dense shade. The 

 leaves are heart-shaped and always one sided. They open 

 late in the spring, and in the latter part of June are followed 

 by clusters of fragrant flowers. They are yellowish-white 

 and are suspended from curious ribbonlike appendages 

 called bracts. 



The flowers mature into pealike seeds which drop from 

 the tree in the fall of the year. The bracts to which the 

 seed clusters are attached act as parachutes, which launch 

 the fruit some distance beyond the tree. The bark of the 

 linden is rather smooth, with shallow, close furrows. The 

 main trunk of this tree frequently extends upward undi- 

 vided to the top, with small branches growing from the 

 limbs all the way up. This characteristic of the linden is 

 especially marked in young trees. Large ones generally 

 have two or three main trunks, like the elm or white maple. 

 After the leaves have fallen the linden displays a graceful 

 outline, making it attractive in winter. 



The American linden is at its best before midsummer. 

 After that time the tree grows coarse and the leaves begin 

 to show the effects of the attacks of the numerous insects to 

 which it is a prey. It is the susceptibility to insect attack 

 that forms the objectionable feature of the tree. In early 

 summer plant lice cover the leaves with patches of honey 

 dew, and the sticky surfaces catch dust and smoke. The 

 leaves are also subject to the attack of a fungus which gives 

 them the appearance of being covered with soot. American 

 lindens are sometimes completely defoliated by the cater- 

 pillars of the tussock moth, and are seriously injured by 

 borers. As a result of the insect attacks the leaves turn 



