PAPERS ON BIOLOGY AND AGRICl'LTURE 87 



A PRELIMINARY KEY TO SOME FOREST 



TREE ROOTS 



Prof. W. B. McDougall. Unrtrsity of Illinois 



During the past several years the writer ha? had occasion 

 to dig up and examine large numbers of tree roots. It has 

 been necessary also to know what kind of roots were being 

 examined in each case. This sometimes has involved hours 

 of hard work, for in the woods where the roots of numerous 

 trees are intermingled it is sometimes necessary to trace a 

 root for a considerable distance through the soil in order 

 to determine to which particular tree it belongs. It early 

 became apparent, however, that there are characteristic dif- 

 ferences by means of which some kinds of roots may be 

 distinguished from certain other kinds. The recognition of 

 this fact led to an attempt to learn the distinguishing char- 

 acteristics of the roots of the genera that were most fre- 

 quently dealt with, and finally to utilize these characteristics 

 in the construction of a workable key. 



It is obvious that a key based on the characters of a single 

 member of the plant cannot be so completely satisfactory as 

 one based on the characters of the plant as a whole. This 

 would be true whether we were dealing with roots, stems or 

 leaves. Yet either stems or leaves might be classified into 

 groups on the basis of readily recognized characters and 

 such classifications might prove very useful in case no other 

 members of the plants were available. Likewise it is true 

 of roots that while it would be impossible to identify many 

 plants by the roots alone yet having learned root character- 

 istics it is easy, for instance, to tell that oak roots are not 

 maple roots. 



The following key and descriptions are offered, then, not 

 as a finished product nor in the hope that it will enable 

 workei's to recognize readily all of the roots considered at 

 all times and under all conditions. They are offered rather 

 as a beginning of an effort to differentiate the roots of 

 woody plants and in the hope that since the scheme has 

 proven of use to the writer it may also be of some service to 

 others. It is entirely possible if not probable that in some 

 instances I have failed to fix upon the most dependable 



