Complimentary 
NEW SERIES VOL. VI 
NO. 16 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN, MASS. OCTOBER 28. 1920 
Some American Plum-trees. North America is the real home of 
Plum-trees as it is of Hawthorns. They range across the continent and 
from the valley of the St. Lawrence nearly to the Rio Grande. Plum- 
trees are most abundant in eastern and southern Kansas, eastern Okla- 
homa, southern Arkansas, and Texas from the valley of the Red River 
to the Edwards Plateau. In this region Plums are represented by 
more species than are found in all the world outside of North America. 
Some are trees of considerable size and others are large or small shrubs 
which frequently spread in sandy soil by means of shoots from the 
roots into often impenetrable thickets covering many acres. It has 
proved difficult to obtain the material needed for a proper study of 
these plants. They flower early when there is little else in bloom to 
occupy the collector, who is obliged to make long and expensive Jour- 
neys to collect the flowers of one genus. In four years out of five the 
young fruit is destroyed by frost which in that region usually comes after 
the flowering of Plum-trees; and when the fruit is not destroyed it is of- 
ten difficult to obtain, for it usually ripens at the season when heat and 
insects make plant collecting difficult and disagreeable. The different 
species are often widely separated and this makes impossible the careful 
comparative study of the living plants needed to understand properly their 
similarities and differences. There is little hope, therefore, that Amer- 
ican Plums can be thoroughly understood before all or most of the 
species can be grown together in one garden until they flower and ripen 
their fruit. Such a collection will be difficult to establish and maintain, 
for some of the interesting species are not hardy in the north, and it 
is not probable that such a collection will be undertaken except in some 
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