COMPLIMENTARY 
NEW SERIES VOL. X 
NO. 7 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN, MASS. JUNE 10. 1924 
Hawthorns. A large number of these trees and shrubs are now in 
bloom; a few have shed their petals and others will not be in flower 
for nearly a month. This genus is chiefly conflned to eastern North 
America where it abounds from Nova Scotia to eastern Texas; it is 
rare in the western part of the continent, and only a few species have 
been found in Asia and Europe. In 1892, when the second volume of 
Sargent’s Silva of North America was published, fourteen species, in- 
cluding one shrub, were described, and in the second edition of Sar- 
gent’s Manual of the Trees of North America published in 1921 there 
are figures and descriptions of one hundred and fifty-three arborescent 
species. A few of the larger specimens are growing along the park- 
way wall between the Jamaica Plain and the Forest Hills entrances, 
but the greatest part of the collection occupies the eastern slope of 
Peter’s Hill where several hundred species are now established. This 
collection was begun in 1899, and the discovery and description of most 
of the species, the raising from seeds here of at least fifty thousand 
of these plants, and the distribution of most of them to other scientific 
establishments and gardens in all parts of this country and Europe can 
perhaps be considered the greatest achievement of the Arboretum in the 
first half century of its existence. Many of the American species are 
good garden plants; most of them are hardy in New England, and they 
grow rapidly into usually round- topped, small trees or shrubs. They 
flower freely nearly every year; the fruit of many of the species is 
ornamental, and on a few of them it remains in good condition well in- 
to the winter or until spring. Unlike most of the genera of the Rose 
Family, Crataegus shows little or no tendency to hybridize, and among 
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