262 GENERAL SCIENCE 



ridges of older bark are gradually pushed outward. The 

 bark grows more and more rough, and in some trees drops 

 off (is " flaky"). In some trees (as birch and cherry) the 

 bark remains smooth and noticeably marked by horizontal 

 streaks. These result from the stretching of the bark due to 

 growth within, and a consequent change of form in the 

 lenticels or breathing pores of the bark. Some inner barks 

 have characteristic tastes readily identifying such trees as 

 the sassafras, slippery elm, birch, cherry, and some oaks. 

 A characteristic general color or tone of the outer bark as a 

 whole is an aid in distinguishing trees. In this latter case 

 there is a difference between their appearance in summer and 

 in winter. 



The leaf scars upon the twigs and smaller branches may be 

 opposite each other at the same node (place where one or 

 more leaves grow), or they may be alternate, with one leaf 

 scar only at a node. These latter are arranged lengthwise of 

 the stem in rows of two or more, and the number of these 

 rows should be determined. 



The presence or absence of a terminal bud on the twig is to 

 be noted, together with the general form of the buds and any 

 general characteristics in their color, odor, and any protective 

 coverings such as hairs, gum, or down. 



The fruits of the tree in season serve to identify it, and so 

 do the flowers. Good cuts in books aid materially in studies 

 such as these. While by use of a reliable and complete 

 "key" one may become fully assured of the identification 

 of any tree, it must always be kept in mind that an acquaint- 

 anceship with trees to be a source of real enjoyment must 

 at first be personal and not bookish. The use of a book in 

 tree studies is like the use of a guide book in one's travels, 

 telling what to look for and its striking characteristics but 

 never taking the place of actual and personal inspection of 

 what is described. 



