46 SHADE-TREES IN TOWNS AND CITIES 



Philadelphia in greater numbers, in fact, than any other 

 single species of tree. Of the 86,000 trees in the city of 

 Paris, over 26,000 are oriental planes. 



The oriental plane is of the same genus as the Western 

 plane or sycamore, or button-ball {Platanus occidentalis 

 Linn. ) , which also makes a splendid street-tree. It resem- 

 bles our native species in leaf, fruit, and bark, but it grows 

 more compactly and symmetrically than the Western plane. 

 The most striking feature of both species of trees is that 

 they shed their bark as well as their leaves. All trees shed 

 their bark to some degree, as the outer layers yield to the 

 pressure of the growing stem. 



The dropping of the bark is noticeable in the silver 

 maple and the shagbark hickory ; and it is especially marked 

 in the planes. The bark of the trunk and larger limbs flakes 

 off in great irregular masses, leaving the surface a mottled 

 greenish-white and gray and brown. The characteristic 

 bark is especially noticeable in winter, although the thickest 

 foliage of summer never quite conceals it. 



The male and the female flowers of the planes are borne 

 in heads on separate buds of the same twigs. The pistillate 

 flowers ripen into the familiar globular fruits of the planes 

 which remain suspended from the slender stems almost the 

 entire winter. The oriental plane can be readily distin- 

 guished from the sycamore after the leaves have fallen. 

 The fruit of the sycamore is generally borne in solitary 

 heads, and in extremely rare cases two heads are found on 

 a single stem. The oriental plane bears from two to four 

 of these globular fruits on a single stem. 



The heads of fruit of the planes are composed of thin 

 seeds, about half an inch long, packed tightly around a cen- 

 tral spherical core. Each seed is surrounded by hairs that 



