CHAPTER VI. 
CLASSIFICATION AND DISTRIBUTION. 
198. We may now proceed to take a hasty survey of the 
vegetable kingdom, studying here and there a selected ex- 
ample which must serve to illustrate the structure of a con- 
siderable group. In such a study of plants it is better to 
begin with the simpler and more easily understood forms, 
and to pass from these to those which are structurally more 
complex and whose functions are correspondingly compli- 
cated. 
199. On account of the vast number of species of plants 
(probably exceeding 150,000) it is necessary for us to group 
them in such a way as to bring together those which resem- 
ble one another. In such grouping we take into considera- 
tion as many things as possible, and those plants which are 
alike or similar in the greatest number of particulars are 
considered to be more nearly related to each other than 
those with fewer points of resemblance. Moreover, it has 
been found that resemblances in structure are of far greater 
importance than resemblances in habits. Two plants, for 
example, may be parasitic in habit, and yet their structural 
differences may be so great as to warrant us in placing 
them in entirely different groups of the vegetable kingdom. 
200. If we bring together all the plants of the vegetable 
kingdom, we may recognize pretty easily six or seven large 
groups, all the members of which show more or less of re- 
