GENERAL AND BASE MAPS, VOLUMES 1-6 
Lists of General and Base Maps (following Contents) in the 6 vol- 
umes of the Atlas, totaling 62, are self-explanatory. All volumes dis- 
play a map of North America. Volumes 1, 3, 4, and 5 contain maps of 
part of the United States with names of counties. Volumes 1, 3, 4, 
and 6 have a map of the United States (contiguous) with names of 
National Forests and National Grasslands. 
Volume | has 9 transparent 2-page folded overlay maps of the 
United States that illustrate special details of the environment, inlud- 
ing geography, climate, and forest types. These maps are equally use- 
ful for Volumes 3 and 4, and the scale remains the same though the 
size of pages and maps has been trimmed. The overlays can easily be 
adapted to the later volumes by tracing boundaries of a few key 
States in pencil and by making new corners. 
The same base map of the United States (contiguous), scale 
1: 10,000,000, has been used in Volumes 1, 3, 4, and 5. It is Albers 
Conical Equal Area Projection—standard parallels 29'/2° and 45'/2°, 
showing State and county boundaries; also latitude and longitude 
marked by crosses at 5-degree intervals. The maps of Alaska in Vol- 
ume 2 have the same scale. The scale for the 35 small maps of Cratae- 
gus, hawthorn, is 1:30,000,000. The 98 maps in Volume 5 of tropical 
hardwoods confined mostly to southern Florida have a scale of 
roughly 1:4,000,000. 
Several base maps and many species maps add letters of compass 
direction after the number. In Volume 1, maps are further labeled 
according to whether they show the eastern (E) or western (W) United 
States. Volumes 3 and 4 have 2 maps for each species with great 
range from north to south. These are indicated in Volume 3 
(Western) as northwestern (NW) and southwestern (SW); in Volume 4 
(Eastern) as northeastern (NE) and southeastern (SE). 
A second or third base map, North America (designated by N), 
(scale roughly 1:27,000,000) is added in Volumes 1, 3, and 4 for the 
species whose natural range extends beyond the limits of the first 
base map. 
ADDITIONS 
Besides Crataegus, hawthorn, Volume 6 has an addition: map 36, 
Juniperus erythrocarpa Cory, redberry juniper. This species named 
in 1936 has been accepted in a recent study of the genus (Zanoni 1978). 
Three shrub species of the Pacific Coast region that rarely attain tree 
size were added to the 1979 Checklist, though not mapped. They are: 
Adenostoma sparsifolium Torr., redshank. Range—Mts. of s. Calif. 
and n. B. Cal., Mex. 
Arctostaphylos glauca Lindl., bigberry manzanita. Range—Mts., 
Coast Ranges mostly, of c. and s. Calif. Also in n. B. Cal., Mex. 
Arctostaphylos viscida Parry, whiteleaf manzanita. Range—Foot- 
hills of sw. Oreg. and s. in Coast Ranges and Sierra Nev. to c. Calif. 
Minor extensions and revisions have been made in the text ranges 
publshed in the 1979 Checklist. However, the maps of previous 
volumes have not been revised or redrafted. 
TREE NAMES 
Scientific names and common names in the Atlas agree with the 
later Forest Service Checklist (Little 1979), with few exceptions. Each 
volume lists changes made after the earlier Check List (Little 1953). 
The 1979 Checklist also contains revisions in common names approved 
by the Forest Service Tree and Range Name Committee. 
Other scientific names in use for the native tree species of conti- 
nental United States not found in the indexes of this volume may be 
sought in the 1979 Checklist. That reference, which contains synonyms 
2 
and other common names, will serve to correlate names that are in 
use but were omitted from the Atlas. 
Several scientific names of species in Volumes 2, 3, and 4 have 
been revised in the 1979 Checklist, as summarized below. 
Amelanchier interior Nielsen, inland serviceberry (vol. 4, map 13), 
is intermediate between A. arborea and A. sanguinea and perhaps 
should be regarded as a hybrid. 
Cecidium texanum Gray, Texas paloverde, includes C. macrum 
Johnst., border paloverde (vol. 3, map 36). 
Heteromeles arbutifolia (Lindl.) M. H. Roem., toyon, replaces 
Photinia arbutifolia Lindl., Christmas-berry (vol. 3, maps 109-NW, 
109-SW). 
Malus fusca (Raf.) Schneid., Oregon crab apple, replaces M. diver- 
sifolia (Bong.) Roem. (vol. 2, map 49; vol. 3, maps 100-N, 100-W). 
Populus fremontii var. mesetae (Eckenwalder) Little, meseta cotton- 
wood, replaces P. arizonica Sarg. (vol. 3, map 115). 
Populus hinckleyana Correll, Hinckley cottonwood, (vol. 3, map 
116), has been reduced to the hybrid Populus angustifolia x fremontii. 
Prosopis juliflora (Sw.) D.C., mesquite (vol. 3, maps 118-N, 
118-SW), as now defined, is native from Mexico southward. The 2 
native species mapped together as varieties under that name are P. 
glandulosa Torr., honey mesquite, and P. velutina Woot., velvet 
mesquite. 
Quercus ajoensis C. H. Muller, Ajo oak (vol. 3, map 130), has been 
reduced to a variety, Q, turbinella var. ajoensis (C. H. Muller) Little. 
Salix bonplandiana H.B.K. Bonpland willow (vol. 3, maps 166-N, 
166-SW), includes as a synonym S. laevigata Bebb, red willow (vol. 3, 
map 176). 
Salix exigua Nutt., sandbar willow (coyote willow) (vol. 3, maps 
168-NW, 168-SW, 168-N; vol. 4, maps 129-NE, 129-SE, 129-N), in- 
cludes as a synonym S. interior Rowlee, sandbar willow (vol. 2, map 24). 
Salix myrtillifolia Anderss., tall blueberry willow, replaces S. 
novae-angliae Anderss. (vol. 2, map 28). 
Salix richardsonii Hook., Richardson willow, replaces S. Janata L. 
ssp. richardsonii (Hook.) A. Skwortz. (vol. 2, map 25). 
Sambucus cerulea Raf., blue elder, replaces S. glauca Nutt., blue- 
berry elder (vol. 3, maps 185-NW, 185-SW). 
Yucca schidigera Roez] ex Ortgies, Mohave yucca, replaces Y. 
mohavensis Sarg. (vol. 3, map 206). 
CRATAEGUS, HAWTHORN 
Thirty-five species of Crataegus, hawthorn, have been accepted in 
the 1979 Checklist (Little 1979, p. 101-118) as native in continental 
United States and are represented by small maps in this Supplement. 
Seven western species were included in Volume 3 (maps 57-63). How- 
ever, the eastern species and eastern ranges of 2 western species were 
omitted from Volume 4 because of taxonomic difficulties. The dras- 
tic reduction from 150 species in the 1953 Check List to 35 in the 
1979 Checklist is explained in the 1979 Checklist, pages 101-105. 
Some States have published or unpublished maps of their species 
but with differing interpretations and synonymy. Thus, this genus 
was omitted in the compilation of records State by State, and no at- 
tempt has been made to plot range limits in detail. 
Two very recent publications should be noted. In his field guide to 
North American trees, Elias (1960) described and illustrated in the 
genus Crataegus only 26 species (including | introduced) and pre- 
pared small maps of 18. Phipps and Muniyamina (1980) in a detailed 
revision for Ontario, Canada, accepted and mapped 39 ‘“‘gocd”’ 
species (including 1 naturalized and 1 of its hybrids). 
The 35 small black-and-white maps (scale 1:30,000,000) show general 
distribution by a dot in each State. Where the range is limited, the dot 
