carry it on the breeze. Sycamore fruits once were favorite foods of the 
now-extinct Carolina parakeet. 
To make certain that trees appearing to be sycamores are the real 
thing, see if there is just one fruit ball dangling on each stalk. The syca- 
more has been crossed with the oriental planetree (Platanus orientalis), 
which has multiple balls per stalk, to yield the commonly planted London 
planetree (Platanus Xacerifolia). Not surprisingly, this hybrid has the 
intermediate number of two balls per stalk. A London planetree and an 
American sycamore can be viewed together near the southwest corner of 
the Lehmann Rose Garden, and an oriental planetree lives on the eastern 
side of the Japanese Garden. Check to see how the leaves of the two 
parental species and the hybrid compare. 
Platanus is an ancient name for the genus. Occidentalis means “west- 
ern”, orientalis means “eastern”, and acerifolia means “maple-leaved”. The 
times sign in Xacerifolia indicates that the tree is a hybrid. 
See Map: X 
TREE-OF-HEAVEN : 
Ailanthus altissima 
A Tree-of-heaven was introduced in 1820 
from China into New York City as a 
street tree and as a potential food for silk- 
worms. In terms of tolerance for poor 
soil and urban pollution, it was a suc- 
cess—too much of a success perhaps. It 
became an urban weed springing up in 
pavement cracks, vacant lots, and 
gutters. The species is short-lived; its 
limbs decay and fall off; the pollen can be 
irritating; the roots clog drains and break 
pavement; the suckers are difficult to 
pinto 1 eradicate; the male flowers stink; and the 
tree houses undesirable caterpillars. 
At its best, however, the tree-of-heaven can be attractive and is valued 
for its beauty in China. The enormous, arching compound leaves suggest 
a coarse tropical atmosphere, looking just a little like palm leaves on 
young trees. The fruits on female trees look like twisted sticks of chewing 
gum and redden in clusters late in the growing season. The “twigs” can 
be the size of walking canes. 
Tree-of-heaven is the only frequently encountered representative of 
the odd Quassia Family (Simaroubaceae). This family, containing about 
36 
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