Complimentary 
NEW SERIES VOL. IV 
NO. n 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN, MASS. JULY 5, 1918 
Summer-flowering Trees. Several interesting trees will flower in 
the Arboretum at different times during the next two months. Among 
these summer-flowering trees are the Chinese Sophora japonica, the 
Maackia of eastern Siberia, Acanthopanax ricinifolius from northern 
Japan, the arborescent Aralias from the southern United States and 
eastern Asia, the Korean and Chinese Evodias, the Sour Wood or Oxy- 
dendrum from our Southern States, the Chinese Koelreuteria and one 
of the American Catalpas (C. hignonoides). It is interesting that only 
three of these trees, one of the Aralias, the Sour Wood and the Cat- 
alpa are American, and that the others have been brought to this coun- 
try from eastern Asia. The most important group, however, of sum- 
mer-flowering trees is 
The Lindens. The flowers of a few of the early flowering species of 
these trees, like the European Tilia platyphyllos and its varieties, and 
T. vulgaris, and the American T. neglecta, are already open; and dur- 
ing the next two or three weeks the flowers of different species of Lin- 
den-trees will open in the Arboretum and attract the bees to their rich- 
est harvest. Linden-trees are very generally distributed in all the 
temperate regions of the northern hemisphere with the exception of 
western North America and, in addition to numerous species, several 
hybrids are cultivated. All the species are very similar in flower and 
fruit, and chiefly vary in the size and shape of the leaves, in the pres- 
ence or absence of hairs on the leaves and branchlets, and in the nature 
of their hairy covering when it occurs. A fact which is not easy to 
explain is the presence in the flowers of all the American species of 
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