Complimentary 
NEW SERIES VOL. V[ 
NO. 10 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN, MASS. JUNE 24. 1920 
Philadelphus. Many additions have been made in recent years to 
this genus by travellers in eastern Asia and by the labors of the plant- 
breeder, and it now constitutes one of the largest and most important 
groups of garden shrubs hardy in the northern states, and to be ranked 
with the Lilacs, Bush Honeysuckles, Viburnums, Azaleas and Cornels. 
The popular names of these plants, Syringa and Mock Orange, are un- 
fortunate for Syringa is the Latin name of the Lilacs and Mock Orange, 
given to them no doubt on account of the perfume of the flowers of 
Philadelphus coronarius of southeastern Europe which for many years 
was the only one of these plants to be found in gardens, does not de- 
scribe the flowers of all the species for many of them are entirely des- 
titute of odor; and Mock Orange, too, is the common name of Prunus 
caroliniana, the Evergreen Cherry-tree of the southern states which 
is much planted there and largely used as a hedge plant. Species of 
Philadelphus are native in the United States in the southern Appala- 
chian Mountain region, in western Arkansas, western Texas, in the 
southern Rocky Mountains of New Mexico and Colorado, and in the 
northwestern states; many species have been found in Japan, Korea 
and western China; and the genus is represented on the Himalayas, 
the Caucasus, and in the Balkan Peninsula. The plants of this genus are 
not particularly interesting in habit; the leaves are dull and fall with- 
out change of color, and the fruit, which is a dry capsule, does not 
add to the attractiveness of these plants, which is to be found only in 
their abundant white, often fragrant flowers. The flowering period of 
the thirty odd species, with many hybrids and varieties in the Arbor- 
etum collection extends through five or six weeks and most of the 
plants flower freely every year. They need rich, well-drained soil, and 
the presence of lime in it has no bad effect on these plants. Better 
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