306 CLASSIFICATION AND DESCRIPTION 



the family or other group to which ]3otanists assigned each 

 plant under consideration, leaving the resemblances and 

 differences thus indicated to be realized more or less vaguelj^ 

 by the student. What was then vague we shall strive now 

 to make more definite, and the student may be assured that 

 very much of what he has been learning about economic 

 plants will prove of service in the present study. 



83. Early attempts at classifying. Perhaps the reader may 

 ask why it is not sufficient for all purposes of study to classify 

 plants according to their uses, somewhat as we have been do- 

 ing. Such a method of classification was indeed employed by 

 some of the earlier writers upon plants; and this was quite 

 natural, since, as we have seen, they were concerned chiefly 

 with plants in their relation to human welfare. But granting 

 that every plant may be of some use (even though not yet 

 discovered) we know that many are useful in more ways 

 than one. Consequently, any classification according to 

 uses would often have to include the same plant in several 

 different groups. Moreover, the great majority of plants 

 are not put to any special use, and affect our welfare only in 

 the same general way as do the economic ones apart from their 

 special uses. Hence, any attempt to classify all plants ac- 

 cording to use would require us to have besides the economic 

 groups, one general group that would include all plants; 

 and in the subdivision of this group we should be face to face 

 with the original problem. 



One of the earliest attempts to avoid this difficulty was a 

 division into herbs, shrubs, and trees. This grouping accord- 

 ing to size and general appearance was a step in the right 

 direction, and for certain purposes is found to be a serviceable 

 arrangement even to-day. Yet, aside from the objection 

 that when applied to all known plants each group includes 

 an enormous number of sorts, there is the further disadvan- 

 tage that such a classification requires one to place in differ- 

 ent groups plants which resemble one another more closely 

 than they do any others of the group in which they are placed. 

 Thus, for example, certain oaks which are nothing but shrubs 

 would on that account be separated from all the other oaks 

 which are trees; the same is true of willows and of manv 



