43 
to open its flower-buds. The leaves are often broader than long, with 
a heart-shaped base, very dark green above and pale below, and rarely 
more than two and a half inches in length. This tree has grown slowly 
here and is still a broad-based, densely branched pyramid. It is not 
common in American plantations, and the Arboretum has not heard of 
any large trees in the United States. In central and northern Europe 
trees a hundred feet tall, however, are not uncommon. The third of 
the Lindens of western Europe, Tilia vulgaris, is believed to be a nat- 
ural hybrid between Tilia platphyllos and T. cordata. It is a large 
tree with leaves dull green on the upper surface, lighter on the lower 
surface and destitute of hairs except in the axils of the veins below; 
in the Arboretum it flowers a week or ten days later than Tilia platy- 
phyllos. There are fine old specimens of this tree in the neighborhood 
of Boston, and it is the best of all Lindens in this climate to shade 
city streets. It is this tree which has been successfully used in Bos- 
ton on Louis Pasteur Avenue which connects the Harvard Medical 
School with Audubon Road. 
The two silver-leaved Lindens of eastern Europe, Tilia tomentosa 
(sometimes called T. argentea) and T. petiolaris, are handsome trees of 
unusual appearance which might well be more often seen in American 
plantations. Tilia tomentosa, which is a common tree in the forests of 
Hungary, is a large tree with erect branches which in this country form 
a broad, compact, round-topped head, and large, erect leaves, dark green 
above and snowy white below. This tree has been a good deal planted 
in the parks of New York City where large and handsome specimens 
can now be seen. It appears to be less well known in New England. 
Tilia petiolaris is a handsomer tree and one of the most beautiful of 
the exotic trees which can be successfully grown in this climate, as can 
be seen in Newport, Rhode Island, where there are many noble speci- 
mens. It is a tall tree with drooping branches which form a narrow 
head, and leaves which are silvery white on the lower surface and, 
drooping on long slender stalks, flutter gracefully in the slightest 
breeze. This tree is not known in a wild state and its origin is uncer- 
tain. Tilia spectabilis, which is believed to be a hybrid of T. petiolaris 
or T. tomentosa with T. glabra, is a handsome fast-growing tree with 
the large leaves of the American species and silvery white on the lower 
surface. This is one of the handsomest Lindens in the Arboretum col- 
lection. The var. Moltkei of this hybrid is a tree of denser habit and 
greener leaves, and in this climate a handsomer and more desirable tree 
than T. glabra. It originated many years ago in the Spaeth Nursery 
near Berlin. The Crimean Linden {Tilia euchlora, sometimes called 
T. dasystila) is distinct in its dark green lustrous leaves, and is believed 
to be a hybrid between Tilia caucasica and T. cordata. This beautiful 
tree is hardy in the Arboretum, but it does not grow as well here as 
the European species and certainly not as well as it does in some of 
the countries of western Europe where it has been used and is recom- 
mended as a street tree. Tilia caucasica, one of its supposed parents, 
is not in the Arboretum collection. 
Asiatic Lindens have not yet given much promise of growing here 
into large or handsome trees. Nearly every species from eastern Asia 
which has been described has been planted in the Arboretum more than 
