Part 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 doing. 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 according 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 according 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 disadvantage that such a classification requires one to place in different 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 other genera that might be mentioned. Crude as this arrangement was, it afforded for many generations the best general classification of plants that anyone had to offer; and it was not until after the revival of learning in Europe, during the sixteenth century, that any important efforts were made to find a better way.