SHRUBS AND TREES. 
127 
the kind above described, as it naturally assumes a parasol-like 
top, grows rapidly, and dispenses with its bottom limbs quickly. 
Being disposed to form crooked stems, some care must be 
used in choosing straight-bodied thrifty nursery trees, and pro- 
tecting the trunks until they are large enough not to need it. 
Six thrifty trees will grow into a perfect canopy, of the size sug- 
gested, within five years, if their central stems are cut back, and 
kept to a height of about eight feet. For the next five years all 
the upright growth at their tops should be annually cut back, so 
that the trees will not exceed twelve feet in height. Afterwards 
they may be allowed to grow naturally ; but their greatest beauty 
will not be attained in less than fifteen or twenty years. 
Fig. 38 shows the ap- 
pearance they should make 
in ten or twelve years after 
planting. 
Next to the sassafras, 
probably the judas or red- 
bud trees, Cerds canadensis 
and C. siliquastrum, form most 
naturally into this kind of flat- 
roofed bower. The White- 
flowered dogwood, Cornus flori- 
da, is also adapted to the same use. Both spread lower than 
the sassafras, but do not grow so rapidly when young. The 
moose-wood or striped-barked maple, on the other hand, attains 
the height required in a single season, and its green and yellow- 
striped bark is ornamental. The branches, after the trunk has 
attained the height of ten or fifteen feet, radiate naturally to form 
a flat-arched head, and grow much slower than the first vigorous 
growth of the stem would lead one to suppose. The foliage is large 
and coarse, but the form of the tree is suited to the purpose under 
consideration. Its large racemes of winged seeds, of a pinkish 
color, are very showy in August. The paper mulberry is also a 
valuable tree for such uses, and attains the required size and 
density of head in less time than any of the others. The foliage is 
unusually abundant and of a dark green color. 
