North America represents a reduction to about one-third the scale of 
the United States base, roughly 1:32,000,000. Thus, | inch equals 
about 500 miles, and | centimeter about 320 kilometers. State and 
national boundaries, principal rivers, and latitude and longitude are 
shown. 
Base map 3, National Forest System and Related Data, shows the 
location of the 154 National Forests, which are widely distributed in 
39 States and also 19 National Grasslands in 1] States. Comparisons 
with a tree species map will indicate the National Forest where that 
species may be expected. Many tree species occur also within 
specially managed areas, such as experimental forests and research 
natural areas. 
List of Maps (pages i-iv) cites the number and order of maps 
of the 166 tree species. For ready reference, the order is alphabetical 
by scientific name. Related species in the same genus are placed 
together. Index of Common Names and Index of Scientific Names 
follow the maps. 
Of the 166 species mapped in this volume, 18 extend vertically 
onto the 2 bases of both northeastern and southeastern United 
States, shown on facing pages. The map of North America is added 
for 42 species whose natural range extends beyond northward into 
Canada or also Alaska or southward into Mexico or farther. 
(Additional maps for a few species were omitted, however.) There is 
a total of 226 pages of individual maps and 4. pages of base maps. 
Where there is more than one for a species, the number is followed 
by letters for the base map: NE (Northeastern United States), SE 
(Southeastern United States), N (North America). If a species has 2, 
the maps are on facing pages. If 3, that of North America precedes 
or follows the others. To avoid separating maps of species, minor 
exceptions to alphabetical order were necessary, as noted under List 
of Maps. 
The legend at the base of many maps contains additional notes. 
For species of local or limited distribution the names of States are 
mentioned. Occurrence beyond the map is also indicated. The latest 
known range of each species is summarized in words under Species 
Ranges (page 6). The Forest Service Check List (Little 1953) 
contained an earlier compilation. 
The natural distribution or range of a tree species, as mapped in 
this Atlas, is the geographical area where the species, including any 
and all varieties, is native or wild. Varieties have not been plotted 
separately, and hybrids are omitted. 
The distribution of the native tree species of the United States is 
mapped as of the present time, exclusive of changes caused directly 
or indirectly by Europeans. However, where modifications have 
occured, the distribution is intended to be before Columbus, or 
pre-Columbian. For nearly all native tree species, the man-caused 
changes in range limits up to the present are believed to be negligible 
or recognizable. In the East, including agricultural and urban areas, 
sufficient scattered trees and secondary forests remain to show the 
natural distribution. However, total destruction has taken place in 
cities and artificial lakes. 
These maps do not show where a species grows outside the natural 
range after having been introduced directly or indirectly by 
mankind, whether planted, escaped, adventive, or naturalized. 
Records of planted or introduced trees outside the continuous 
natural ranges have not knowingly been mapped. Reports of trees 
planted for forestry, shade, or other purposes and of escapes from 
cultivation have been omitted. Also excluded are naturalized trees, 
those introduced outside their natural range and thoroughly estab- 
lished and reproducing as though native. 
Perhaps in the future, maps adding forest plantations or other 
successful introductions beyond the original occurrence may merit 
compilation. In the meantime, maps of Plant Hardiness Zones, such 
as overlay 4 of Volume | (Little 1971a; U.S. National Arboretum 
1965), may suggest roughly where a species would be hardy when 
planted outside its natural range. 
The natural geographic distribution of each species is shown as a 
brown-shaded pattern of fine dots on the black-and-white base map. 
Outlying stations or outliers are shown similarly by large or small 
dots according to size. However, the smallest areas, such as a grove 
with only a few trees, must be enlarged to a dot, representing several 
miles in diameter, to be visible on a map. Width of strips, such as 
along rivers, has been broadened slightly. A few localities beyond the 
main range, where a species is shown to have occurred naturally 
within historic times but is now extinct, are designated by X. Arrows 
have been added to direct attention to isolated dots. 
Presence or absence is shown, but not abundance or density. Large 
areas within the main range where a species is known to be absent 
(for example, high mountains) are marked by borders or holes 
unshaded within. Commercial range, formerly indicated on some old 
maps, is not designated. Altitudinal limits, which vary in different 
latitudes, are not indicated. 
The North American map of a species repeats on smaller scale the 
distribution pattern from the United States base. Additional dots 
beyond the main range in Canada and Mexico mostly are fewer and 
scattered and are enlarged for clarity. 
The species maps do not indicate forest types, or forest cover 
types, which are the subject of overlay 9, Major Forest Types, 
Volume 1. Most tree species are not confined to a single forest type 
and have ranges somewhat beyond. However, many species are 
characteristic of and largely within certain broad types. Published 
colored maps of yegetation and forest types have been mentioned. 
Colored maps of forest types are contained in forest survey 
publications by the Forest Service for States. The comprehensive 
classification of forest cover types prepared by the Society of 
American Foresters (1954) lists species but lacks maps. 
A few tree species have spread widely by planting or other 
introductions and have become so thoroughly naturalized that the 
limits of their original ranges are in doubt. Catalpa bignonioides, 
southern catalpa, is an illustration in this volume. Trees with edible 
seeds or other useful products may have been disseminated by the 
American Indians, for example, Prunus angustifolia, Chickasaw 
plum. 
TREE NAMES 
Scientific and common names follow the Forest Service Check List 
(Little 1953), except for several minor changes in nomenclature to 
be made in the forthcoming revision. Differences in scientific names, 
mostly of additions and deletions, are given below, the accepted 
name cited first. The first three changes below inyolve the 
substitution of an older specific name. 
Avicennia germinans (L.) L., black-mangrove, replaces A. nitida 
Jacq. 
Cladrastis kentukea (Dum.-Cours.) Rudd, yellowwood, replaces C. 
luted (Michx. f.) K. Koch. 
Sabal minor (Jacq.) Pers., dwarf palmetto, formerly omitted as a 
shrub, includes S. louisiana (Darby) Bomhard, Louisiana palmetto, a 
name applied to plants with trunks. 
The 8 additions which follow include 7 large shrubs also reaching 
tree size and | (the last) formerly treated as a variety. 
