Complimentary 
NEW SERIES VOL. V 
NO. 17 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
i* Jv l8 , 9 | 
Ai'N/ Muse«^ 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN, MASS. NOVEMBER JO, 1919 
Conifers. Representatives of only fourteen genera of the twenty- 
nine genera into which conifers are now usually divided can be grown 
in the northeastern states. None of the five genera which are con¬ 
fined to the Southern Hemisphere can be grown here, and of the two 
genera Callitris and Libocedrus which have representatives north and 
south of the equator only the North American Libocedrus is growing 
in the Arboretum. Seven of the genera of eastern Asia consist of a 
single species, but unfortunately only three of these interesting trees, 
Pseudolarix, Sciadopitys and Cryptomeria, find places in northern col¬ 
lections. Of the other genera with hardy representatives only Taxo- 
dium is confined to North America, the others being widely distributed 
through the Northern Hemisphere. Important genera of the Northern 
Hemisphere with more than one species which cannot be grown in the 
Arboretum are the Chinese Keteleeria and Cunninghamia, Sequoia and 
Cupressus. 
Pimis among the conifers contains the largest number of species 
and, with the exception of Juniperus, is the only northern genus which 
extends into the tropics. It is not surprising, therefore, that of the 
some seventy species of Pinus which botanists now generally recognize 
less than half are in the Arboretum collection where there are now 
growing twenty-seven species with numerous distinct geographical 
varieties. The collection contains all the species of the northeastern 
and middle United States, eastern Canada and the Rocky Mountains, 
but only four or five of the Pacific Coast species. The Pines of 
Mexico, which is one of the headquarters of the genus, are repre¬ 
sented only by Pinus ayacahuite. Europe has contributed to the col- 
65 
