306 CLASSIFICATION AND DESCRIPTION 
the family or other group to which botanists assigned each 
plant under consideration, leaving the resemblances and 
differences thus indicated to be realized more or less vaguely 
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 many 
