It is indeed unfortunate that Sudworth’s entire Atlas, with a map 
for each of nearly 500 native tree species then distinguished, was not 
issued promptly, when the maps represented current knowledge. 
Some years later, Munns (1938) published distribution maps of 170 
important forest tree species of the United States. With minor 
additions, the maps were based very largely upon data by Sudworth, 
who died in 1927. 
Besides “Volume 2, Alaska Trees and Common Shrubs,” other 
publications of the Forest Service have been devoted to maps of the 
trees of a single State. In 1941-50, the Forest Survey published 
distribution maps of commerical forest trees in four Southeastern 
States, Mississippi, North Carolina, South Carolina, and Virginia. 
“The Distribution of Forest Trees in California,” by James R. 
Griffin and William B. Critchfield (1972), has detailed maps of 86 
species of that State, including the conifers and commercially 
important hardwoods and most other large trees. 
COVERAGE OF THIS VOLUME 
“Atlas of United States Trees, Volume 4, Minor Eastern Hard- 
woods” continues “Volume |, Conifers and Important Hardwoods.” 
The Forest Service “Check List of Native and Naturalized Trees of 
the United States” (Little 1953) serves as a basis for the species 
included as trees, their accepted scientific names, and their approved 
common names. That reference contains other common names in 
use (“Index of Common Names,” p. 451-472) and current synonyms 
of the scientific names. Thus, names of species not found in this 
volume may be traced and correlated. Several minor changes in 
nomenclature accepted after publication of the 1953 edition are 
noted under ““Tree Names” (page 5). 
The Check List apparently is the only current compilation of the 
native woody-plant species that reach tree size and that should be 
mapped in this Atlas. Obviously, the number of tree species included 
here depends somewhat upon the definition used. That of the Check 
List (Little 1953, p. 5) is followed and repeated here, with insertion 
of approximate metric equivalents (and slight increase in height to 
agree): Trees are defined as woody plants haying one erect perennial 
stem or trunk at least 3 inches (7.5 centimeters) in diameter at 
breast height (4/2 feet or 1.3 meters), a more or less definitely 
formed crown of foliage, and a height of at least 13 feet (4 meters). 
Large willows (genus Salix) with several trunks from the same root 
have been included. However, a few species of willow rarely 
recorded as trees have been excluded, as cited under “Tree Names.” 
Species whose individuals sometimes reach the above dimensions 
somewhere within their natural range have been included in this 
Atlas as well as in the Check List. Many of the minor hardwoods 
mapped here are commonly smaller over most of their ranges and are 
regarded locally as shrubs. Several borderline species were mentioned 
in notes in the 1953 Check List. Most of those are described in 
current floras as becoming small trees and have been added here 
under “Tree Names.” Inclusion of these shrubby trees has increased 
the number of maps and also time of preparation. Obviously, many 
species of large shrubs are excluded. Thus, the extra maps of this 
volume may be useful in the absence of a similar Atlas on the larger 
number of native shrubs. 
“Volume 4, Minor Eastern Hardwoods,” with 166 species not in 
previous volumes, aims to complete the maps of the tree species 
native in eastern contiguous United States, except the tropical trees 
of southern Florida and the genus of hawthorns (Crataegus). Volume 
1 has about 121 eastern tree species, all the eastern conifers, or 
cone-bearing softwoods, including the needleleaf evergreens, totaling 
2 
32 species (also 2 shrubs) and 89 species of hardwoods classed as 
important. The total number of eastern tree species mapped in both 
volumes as native is approximately 287. 
‘The trees of this volume are classed as angiosperms or flowering 
plants. The term hardwood generally is used for trees of dicotyle- 
dons, flowering plants with trunks of bark and wood usually hard, 
which increases in thickness by annual growth rings. Also added to 
this volume are 4 tree species of monocotyledons, flowering plants 
whose trunks are not divided into bark and wood and whose less 
compact woody tissue does not increase in thickness by growth 
rings. These southeastern monocotyledons are included here for 
completeness, though technically they are not hardwoods. Two 
southeastern species of Yucca, yucca, reach tree size. This volume 
has 2 species of palms that rarely attain the minimum dimensions, 
Sabal minor (Jacq.) Pers., dwarf palmetto, and Serenoa repens 
(Bartr.), Small, saw-palmetto. Also, Sabal palmetto (Walt.) Lodd., 
cabbage palmetto, is in Volume 1, and Sabal mexicana Mart., 
Mexican palmetto, of extreme southern Texas, is in Volume 3. Six 
species of tropical palms of Florida will be mapped in Volume 5. 
The area covered in Volume 4, with the exceptions noted below, is 
eastern contiguous United States from Maine west to North Dakota, 
south to Texas (except Trans-Pecos Texas), and east to Florida 
(excluding tropical trees of the southern part). These 37 Eastern 
States are in base maps 2-NE and 2-SE. 
A sharp separation of species geographically into different volumes 
was not practicable. Most tree species clearly are eastern or western, 
but several are widespread across the country and some overlap 
along the central part. For most Eastern States, only Volumes | and 
4 should be consulted. These are the 31 States from Maine west to 
Minnesota, south to Louisiana, and east to Georgia and Florida 
(except the southern part). 
“Volume 3, Minor Western Hardwoods” is needed also for 6 
intermediate Midwestern States: North Dakota, South Dakota, 
Nebraska, Kansas, Oklahoma, and Texas. Most tree species in these 
States will be found in Volumes | and 4. However, about 30 species 
of western hardwoods of Volume 3 extend eastward from the 11 far 
Western States into 1 or more of the above 6 but not beyond. Thus, 
the entire range is shown ona single map in Volume 3, not repeated 
here. 
Trans-Pecos Texas (the southwestern part west of the Pecos River) 
is treated with the 11 far Western States in Volume 3. Also mapped 
there and omitted here are about 15 species of subtropical trees 
which extend northward from Mexico into southern Texas but no 
farther eastward. 
For nearly all tree species, the entire natural distribution is 
mapped in one volume. However, about 20 of Volume 4 are 
widespread across the country or both eastern and western. The 
entire range of several is shown on a map of North America. Detailed 
maps showing occurrence by counties in Western United States are 
in Volume 3. 
A separate volume will be devoted to the native trees of Florida, as 
noted before. Many native trees of Florida are mapped in Volumes 1 
and 4. Southern Florida has nearly 100 additional species of tropical 
trees native nowhere else in continental United States. “Volume 5, 
Florida” will contain these tropical trees on large base maps and the 
other native trees on small maps adapted from Volumes | and 4. 
The genus of hawthorns (Crataegus) has been left out of this 
volume because of taxonomic difficulties, as noted. In Volume 3, 
however, 7 western species are mapped. More than 1,100 specific 
names were published for the native plants of this genus, nearly all in 
the quarter century beginning about 1899 by three investigators 
working independently. The taxonomic group of species became a 
