DENDROLOGY. 



Data on range of 

 trees. 



Each district forester will be supplied with folio maps showing 



ranges of all species occurring within his district. The 

 ran g es ^{\\ b e complete so far as available records can 

 make them so. Extensions of range discovered within 

 each district, after the maps are received, should be promptly add<>d 

 to the map or maps on file and a transcript of the addition on tracing 

 paper forwarded to the Washington office for record. The Washing- 

 ton office maintains a set of tree distribution maps for North America 

 and desires the systematic cooperation of the district foresters in 

 making these records as complete as possible. All extensions of range 

 discovered by the Washington office will be promptly forwarded to the 

 district foresters concerned. 



In case of doubt as to the identity of a species, of which extended 

 range is discovered, adequate specimens, flowers, if 

 spwi?^ ** 1011 f possible, but in all cases mature foliage, together with 

 mature fruit whenever this is obtainable, should be 

 forwarded to the Forester for identification. Notes should accom- 

 pany the specimens, giving as accurately as possible the location of the 

 species found and the extent to which it occurs ; also the character of 

 soil, aspect of slope, approximate (if not exact) elevation, associated 

 species, how the species occurs scattered, in open, dense, or continu- 

 ous stand. When necessary to name small, little-known streams, 

 lakes, mountains, etc., as locations for new ranges, these must be con- 

 nected by reference with larger well-known streams, watersheds, etc., 

 so that the area can be accurately located on a map. 



District Forest officers are urged to cooperate as fully and as dili- 

 gently as possible with the dendrologist in obtaining full and accurate 

 records of the horizontal and vertical ranges of trees within their 

 respective districts. Present knowledge of the ranges of our trees is 

 very imperfect. For many species it is only general, requiring much 

 careful exploration to work out the actual limits. Definite records of 

 occurrence, even within the generally known range, are desirable, 

 while those which permit drawing outside limits of a range are par- 

 ticularly valuable. 



All field reports, notes, etc., describing the occurrence of trees, 

 should preferably refer to species by their technical 

 names; otherwise the accepted common name of the 

 Check List? (Bulletin 17) should be used. Use of such 

 indefinite or confusing names as pinon, juniper, cedar, cypress, moun- 

 tain mahogany, magnolia, spruce, larch, fir, oak, etc., should be 

 avoided when describing or referring to a particular species. Much 

 valuable, and probably new, information in field reports which include 

 matter on the geographic ranges of trees can not be used now because 

 the unfortunate use of such indefinite names makes it impossible to be 

 sure what species the writer saw. 

 36 



Indefinite common 

 names of trees. 



