44 
TREES AS GOOD CITIZENS 
lina Poplar is one of the worst offenders. Its brittle 
quality causes limbs to break, while its bulging roots and 
trunk mar the evenness of curb and sidewalk and cause 
cracking of concrete or flagstones; and the dropping of 
spring blossoms is so extensive as to become a nuisance. 
Silver Maples break sidewalks through the action of 
their roots, and have disadvantages similar to those of the 
Carolina Poplar. The staminate (male) Ailanthus is 
objectionable to many because of the unpleasant odor of 
its flowers, and care should be taken to use only pistillate 
(female) trees, the flowers of which lack this odor. Only 
the staminate or non-fruit-bearing form of the Ginkgo 
should be used as the falling fleshy fruits not only make 
the pavement slippery, but are somewhat poisonous 
to the skin of some people. The Cottonwood spreads 
its seeds in the form of a fine cotton or down which 
is quite objectionable because it is often irritating to the 
respiratory organs and is most untidy. It can be avoided 
by using staminate trees only. As Poplars are grown 
from cuttings, trees of the desired sex may be obtained by 
making cuttings from trees of that sex. Root cuttings 
from an ungrafted tree of the proper sex could be used for 
propagating the Ailanthus, but the Ginkgoes would have 
to be grafted. 
A final consideration, but by no means the least 
important, is the element of beauty. This involves form, 
vigor and suitability to location and environment. 
Factors of beauty also include the coloring of the leaves 
and the nature and appearance of flowers or fruit. Fine 
examples of coloring are to be found in the brilliant 
autumn foliage of the Red Oak, following its summer 
dress of heavy dark-green leaves. The gorgeousness of the 
Maples in autumn coloring makes these trees general 
favorites for street planting. Of the Horse Chestnut, the 
