SOURCES OF INFORMATION 
Forest trees of economic importance differ from most 
other plants in the very diverse kinds of information that can 
be used in mapping them. Publications for tree identifica- 
tion, floras, vegetation maps, forest-type maps, and a sizable 
part of the literature of forestry and plant ecology are 
sources. ‘Travelers’ accounts can occasionally be used, and 
zoological studies are sometimes helpful—for example, a 
report by J. I. Marshall (1957) on the birds of the pine-oak 
woodland of northern Mexico is an important source of 
information about pine species distribution in that region. 
Dot maps based on herbarium specimens convey only a frac- 
tion of the available information, and we have used them 
only for the pines of Mexico. The main source of distribu- 
tion information about these Mexican species is Martinez 
(1948), who lists the localities where each species was col- 
lected. For the other pines, we have incorporated the 
available information into maps showing their total distri- 
bution, often with a special symbol (x) to indicate isolated 
or scattered occurrences. 
The amount and quality of published information about 
where pines grow varies greatly from species to species and 
from country to country. The distribution of such economi- 
cally important species as Pinus ponderosa, P. sylvestris, and 
P, pinaster is usually better known than that of species hay- 
ing little or no economic importance, such as P. albicaulis, 
P. mugo, and P. pumila. 
The countries of eastern Asia present the greatest ex- 
tremes in available information: The pines of Japan have 
all been mapped in detail at a large scale (Hayashi 1952, 
1954), whereas the natural distribution and even the identity 
of some of the pines of eastern and northeastern China are 
uncertain. More is known about the distribution of pines in 
some of the remotest parts of western China than in eastern 
and southern China because of the remarkably concentrated 
plant exploration of parts of Kansu, Szechuan, Sikang, and 
Yunnan provinces (Cox 1945). In western and southern 
Europe, the distribution of the pines of Switzerland and 
Yugoslavia is more fully documented than that of most other 
countries. In the Western Hemisphere, poorly known areas 
include northwestern Canada, parts of the Great Basin and 
adjacent regions in western United States, parts of Mexico, 
and much of Honduras. 
We have supplemented the published sources of informa- 
tion by having preliminary versions of all of the maps re- 
viewed by specialists. “The European and American species 
received a more thorough review than the Asian species. 
Information obtained from reviewers and cited here is filed 
at the Institute of Forest Genetics, Placerville, Calif. Addi- 
tional working maps of the pines of the United States are in 
the files of the Forest Service dendrology project at Wash- 
ington, D.C, 
With certain exceptions, all of the published and unpub- 
lished sources of information are cited with brief notes on 
each species. Where a source pertains to only one or two 
countries, states, or provinces, these are indicated in paren- 
theses. ‘The following abbreviations are used for countries, 
states, and provinces: 
2 
Countries: 
Union of Soviet Socialist Republics 
United States of America___ 
States (U.S.): 
Arizona 
California 
Colorado 
Florida 
Illinois 
Indiana 
Minnesota 
Missouri 
Montana 
Nebraska 
Nevada) Baebes Remit sine 
New Hampshire 
New Mexico_ 
New York_ 
North Carolina 
North Dakota 
Oregon 
Pennsylvania 
South Carolina 
Washington 
Wyoming 
Provinces (Canada): 
Alberta 
British Columbia__ 
Newfoundland 
Nova Scotia 
Ontario Zoe See eee 
Owebec Lee Ss zs 
Q) 
States (Mexico): 
Aguascalientes 
Baja California 
Chika a's) yp 3 cotillion ya 
Chihuahua 
Coahuila 
Durango 
Guerrero 
Hidalgo 
Jalisco 
México 
Nayarit Woe MAUS Soe OS 
Nuevo Leon 
Oaxaca 
Puebla 
@UEKE tao; sees eae ee 
San Luis Potosi_ 
Sinaloa 
Sonora 
Tamaulipas 
Veracruz __ 
Zacatecas 
Abbreviation 
Ind. 
Minn. 
Mo. 
Mont. 
Nebr. 
Nev. 
N.H. 
N. Mex. 
INSYS 
N.C. 
N. Dak. 
Oreg. 
yas 
S.C. 
Wash. 
Wyo. 
Alta. 
BAG 
N.F. 
N.S. 
Ont 
Que. 
Ags. 
Baja 
Calif. 
Chis. 
Chih. 
Coah. 
Dgo. 
Gro. 
Hgo. 
Jal. 
Mex. 
Mich. 
Nay. 
N.L. 
Oax. 
Pue. 
Qro. 
Sues 
Sin. 
Son. 
‘Tamps. 
Ver. 
Zac. 
