Important Forest Trees of the United States 



765 



To assist in the identification of 

 trees, a simplified key, based chiefly 

 upon leaves and twigs, has been in- 

 serted in the text. This key is an out- 

 line in which trees with certain char- 

 acteristics in common are grouped to- 

 gether. The name of a tree specimen is 

 found by elimination through succes- 

 sive selection of one from a pair of 

 groups, with descriptive characters 

 that fit the specimen. The paired 

 groups are designated by the same let- 

 ter, single and double, beginning with 

 "A" and "AA," at the left of the page. 

 Under the group fitting the specimen, 

 the elimination continues with the 

 next paired groups indented below, 

 such as from "AA" to "N" or "NN" 

 and from "NN" to "O" or "OO," the 

 pair next indented to the right, until 

 the name is reached. Some descrip- 

 tive notes applying to a genus have 

 been inserted in the key and not re- 

 peated in the notes under each species. 

 The key is limited to the tree species 

 represented here and will not serve to 

 identify other trees. Identifications, of 

 course, may be made directly from the 

 drawings, maps, and descriptive notes, 

 without use of the key. 



The arrangement of species in the 

 lists of eastern and western trees is 

 artificial, to fit the key, rather than 

 botanical. In each list the conifers are 

 placed first, sorted into those with 

 needlelike leaves and those with scale- 

 like leaves, followed by broadleaf trees. 

 The latter are grouped into trees with 

 paired (opposite) simple leaves, trees 

 with paired (opposite) compound 

 leaves, trees with single (alternate) 

 compound leaves, and trees with sin- 

 gle (alternate) simple leaves, with the 

 oaks placed last. (A compound leaf is 

 divided into leaflets, which usually are 

 smaller than leaves and are attached 

 on a common leafstalk that sheds with 

 them. Also, the leaf has a developing 

 bud at its base, while the leaflets of a 

 compound leaf do not.) 



Various handbooks, manuals, and 

 other publications may be consulted 

 for the identification of the trees of 

 the United States, especially those not 



found here, and for additional infor- 

 mation. A list of 30 references for 

 identification of trees, both popular 

 and technical, including the illustrated 

 books on the commoner trees of the 

 United States and books on the trees 

 of geographic regions, will be found in 

 the bibliography. Trees are described 

 also in the various botanical floras and 

 manuals, usually technical and with- 

 out illustrations, which have been pre- 

 pared for geographical regions, single 

 States, or smaller areas. 



The State forester can furnish infor- 

 mation about publications on the trees 

 of your State and how to obtain them. 



To identify with certainty the nu- 

 merous kinds of native trees, some of 

 which differ but slightly, some knowl- 

 edge of systematic botany or dendrol- 

 ogy as well as of the technical termi- 

 nology is desirable. Properly prepared 

 dried and pressed botanical specimens 

 of twigs with leaves and flowers or 

 fruits may be submitted for identifica- 

 tion to specialists, such as to depart- 

 ments of botany and schools of forestry 

 in universities and colleges, to botani- 

 cal gardens, herbaria, and museums, 

 or to the United States Department of 

 Agriculture. Specimens should be ac- 

 companied by notes, such as locality 

 where found, collector's name, date, 

 size, whether wild or planted, and other 

 data of interest. Material for the De- 

 partment of Agriculture may be sent 

 to either of the following : Forest Serv- 

 ice, Washington 25, D. C.; or Bureau 

 of Plant Industry, Soils, and Agricul- 

 tural Engineering, Plant Industry Sta- 

 tion, Beltsville, Md. 



On the next two pages are indexes 

 of common and scientific names of the 

 species discussed on pages 768-814. 

 Thus, a reader who wishes to look up 

 pecan finds that it has the number 41 

 in the index of common names. By 

 going through the list, he finds pecan 

 described on page 780. 



Or, if he encounters the scientific 

 name Carya illinoensis, he will learn 

 from the index of scientific names that 

 it is number 41 and described (as 

 pecan) on page 780. 



