NEW SERIES VOL. I 
NO. 10 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN. MASS. JUNE 28. 1915 
Philadelphus. In 1811 English gardeners cultivated only two species 
of Philadelphus and twelve years later botanists recognized only eleven 
species. There are now established in the Arboretum some thirty 
species and a large number of varieties and hybrids. All these plants, 
popularly called Syringas, are easy to manage, demand no special care, 
and suffer less from the attacks of insects than most trees and shrubs. 
They flower freely year after year, their flowers are often very fra- 
grant, and in rich well-drained soil the plants live for many years. 
Some of the species can grow under the shade of overhanging trees, 
and flower in such situations more freely than almost any other shrub. 
The beauty of these plants is found in their white flowers; the fruit, 
which is a dry capsule, has as little beauty as that of a Lilac. There 
is nothing distinct or particularly interesting in the habit of the plants 
of any of the species, and the leaves fall in autumn without brilliant 
coloring. As flowering plants not many shrubs, however, surpass them 
in beauty, and their value is increased by the length of the flowering 
season which extends in the Arboretum during fully six weeks. Some 
of the species hybridize freely and several of the handsomest of these 
plants are hybrids. One of the first of these hybrids to attract atten- 
tion was raised in France before 1870 by Monsieur A. Billard; it is 
known as Philadelphus insignis and sometimes is called Souvenir de 
Billard. It is one of the handsomest of the large-growing Syringas, 
and the last or nearly the last to bloom in the Arboretum, for the 
flowers will not be open for another fortnight. A hybrid probably 
between P. grandijlorus of the Appalachian Mountain region with a 
species from our northwest coast appeared in the Arboretum a few 
years ago and has been named P. splendens; it is a large and vigorous 
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