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exposed position. The Silver Poplar of northern China (P. tomentosa) is 
one of the handsomest of all Poplar-trees. It has grown fairly well 
in the Arboretum but it is too soon to form an opinion of its value in 
this country. 
Two European tree Willows, Salix alba and S. fragilis, and some of 
their hybrids have become naturalized in the northeastern states where 
they grow as large or even larger than in Europe and are important 
additions to the North American silva. The so-called Wisconsin Wil- 
low, a natural hybrid between <S. babylonica and S. alba, and other 
hybrids of the same parentage, are useful ornamental trees in the 
northern states. 
Cercidiphyllum is the largest deciduous-leaved tree of Japan, and 
although it was introduced into the United States only forty years ago 
it promises to become a permanent addition to the trees of large 
size which can be successfully grown here. The Chinese White Mul- 
berry {Morns alba) is a larger and hardier tree in New England than 
the Mulberry-tree of the eastern states, and is perfectly at home here. 
Probably the most generally useful, however, of the large deciduous- 
leaved trees which have been brought into the northern states is the 
Ailanthus of northern China. It is perfectly hardy and grows rapidly 
and it can resist the heat, drought and dryness which trees have suf- 
fered in our -cities better than any other tree with the exception per- 
haps of some of the Poplars. The Ailanthus, too, produces wood which 
is valuable in cabinet-making. 
Of all the Elm-trees of the world not one equals in grace and beauty 
the White Elm of eastern North America, Ulmus americana. It is a 
true lover of the country, however, and only shows its greatest beauty 
in the deep moist soil of a New England intervale; moved to the city 
it soon languishes, for It resents city conditions of overdrained soil, 
smoke and bad weather. One of the so-called English Elms, known 
usually as U. campestris, is better able to thrive in cities where the 
American Elm fails, and in Boston and its suburbs this tree has been 
growing for more than a century and has proved itself valuable. It is 
now known that this name must be abandoned as there are four Brit- 
ish Elms and a species of northern and eastern Europe which were in- 
cluded in Linnaeus’ description of the European Elm. The tree which 
has usually been called the English Elm in Boston under the name of 
Ulmus campestris has been growing certainly for more than a century 
in Massachusetts where it has attained a large size. More than a cen- 
tury ago Major Paddock had a nursery at Milton for the propagation 
and sale of this tree. Probably no tree, native or foreign, which has 
been planted in the neighborhood of Boston has grown to such a size. 
The Paddock Elms which stood on Tremont Street in front of the 
Granary Burying Ground were of this species, as were the great Elms 
on the Tremont Street Mall of the Common which were killed by the 
Subway. The Elm-trees on each side of the Shaw Monument opposite 
the State House are of this species, and there are still large specimens 
in the suburbs of the city. 
None of the exotic Ash-trees are really valuable in New England. 
For general planting in the eastern United States no Ash is as good as 
