248 FORESTS AND TREES OF NORTH AMERICA. 



the most skilful botanists. The specimens from each tree should be 

 tept carefully together, and the name of the locality and collector 

 given in full. Without such collections no information as to the 

 large genera of oaks, hickories, magnolias, and, in fact, most others, 

 can be at all depended on or made use of. Collections from the ex- 

 treme corners of the United States, and from any part of the western 

 mountains, will be particularly useful in determining all these ques- 

 tions. A good way of preserving a complete set from each species of 

 tree is to obtain two pieces of the thick bark of the trunk about a foot 

 square, talcing care not to ruh off the mosses w lichens^ which are often 

 very characteristic of the tree. Other specimens of bark from the 

 branches, sufficient to show all its changes in appearance, and twigs 

 with leaves, flowers and fruits, may be pressed between the trunk 

 bark, with sufficient paper of any kind intervening, to absorb all 

 moisture. One change of this paper will usually be sufficient, 

 (especially if the bark is dry ;) and fruits, if large and hard, may 

 be so fixed as to hang outside^ wrapped in paper. Particular care is 

 necessary to prevent mixture of specimens. Blocks of wood from the 

 trunk and branches at various seasons are also desirable for experi- 

 menting upon. 



Observations as to the relative abundance of each tree at the various 

 stations may be expressed numerically, thus : very rare, 1 ;. occasion- 

 ally met with, 2 ; not uncommon, 3 ; common, 4 ; very common, 5 ; 

 abundant, 6, &c.; using numbers up to 10, and explaining them. 

 Frequently several trees will be found so nearly alike in abundance as 

 to require the same number. Notice should also be made of the 

 nature of the country and soil — whether mountainous, rocky, gravelly^, 

 sandy, or swampy, which will help to determine the limits of the 

 natural regions. The geological structure of the district is, however, 

 of secondary importance. 



The columns of range may be used by observers filling the blanks 

 or adding to the recorded range in either direction ; but this must be 

 done carefully and with a perfect knowledge of the species noted. 

 The name of the county should be given as well as of the town, and is 

 preferable if only one is stated. Such blanks, filled up, may be cut 

 out and sent to the Smithsonian Institution, addressed to the Com- 

 missioner of Patents, with the writer's name. Meteorological ob- 

 servers will take a special interest in the subject, and in most cases 

 can make the best notes from their habit of observing the connexions 

 of peculiarity of climate and forest growth. 



In the annexed catalogue generic and general English names are in 

 capitals. The most important synonyms are given in italics, as well 

 as local or little-used English names. 



The following is a list of the principal authorities consulted in col- 

 lation of the facts regarding the distribution of trees of the United 

 States, and in the preparation of the map : 



Michaux's Sylva. 



BrowD, Trees of America, vol. I. 



Torrey and Gray's Flora of North America, vol. 1, 11. 



Gray's Botany of the Northern States, ed. 1857. 



Lewis and Clarke's Travels, (Pursh Botany.) 



Long's Expedition. Botany by Dr. James, Say and Torrey, In Ann. Lye. New York. 



