SPECIES FOR STREET-PLANTING 51 



brownish purple and yellow. Like most trees with large 

 compound leaves, the ash sheds its spray with the foliage in 

 the fall, leaving the erect rigid twigs that somewhat detract 

 from the beauty of the tree in winter. When stripped of 

 foliage the characteristic open head of the tree is marked. 

 The bark is closely furrowed with irregular ridges and the 

 twigs form a network of crosses against the sky. 



The staminate, or male flowers, and the pistillate, or 

 female flowers, are borne on separate trees. They open in 

 May before the leaves and are borne in small, compact clus- 

 ters. The staminate, or male trees, ordinarily shed their 

 flowers about the time the leaves unfold, when the bursting 

 pollen shells are mature. Sometimes the undeveloped male 

 flower clusters are attacked by tiny mites that cause them 

 to change into berrylike growths, which hang on in dry 

 clusters on the ends of the branches. Frequently these 

 abnormal formations, which resemble the familiar oak-galls, 

 are mistaken for the fruit of the ash. 



The pistillate, or female flowers, mature into seeds. The 

 fruit of the white ash comes in crowded, drooping panicles 

 which hang upon the branches until after the leaves have 

 fallen, almost until midwinter. On examination it will be 

 found that each seed of the ash is provided with a thin 

 membranous appendage, or wing, which keeps the seed bal- 

 anced in the air when it drops from the tree and allows the 

 wind to carry it far from the parent tree. 



Hackberry {Celtis occidentalis Linn. ) . The hackberry is 

 a medium-sized tree, which, in its general appearance, 

 resembles the elm. Its straight trunk does not divide until 

 it has attained considerable height, a peculiarity which is 

 an advantage in a street-tree. It is tolerant of many con- 

 ditions of soil and climate, prefers rich, moist soil, but can 



