160 PRACTICAL BOTANY 



be inconvenient and confusing. How plants live and the rela- 

 tions that they bear to other living things are the really im- 

 portant things, and though names are quite necessary, we must 

 keep clearly in mind that they are merely tools, by means of 

 which, in our thinking and speaking, we may easily handle 

 plants. There are two great pieces of work that plants do, as 

 has been made evident in the preceding chapters : plants must 

 have ways of securing and using the needed food materials, 

 they must attend to the needs of nutrition ; and they must 

 attend to the establishment of succeeding generations of their 

 kind, the work of reproduction. All that plants do may in 

 some way be related to one or both of these two great pieces 

 of work. Protection through the winter seasons and drought, 

 and responses to the conditions of life in water or in tropical 

 regions are in some way related to nutrition and reproduction. 

 While, therefore, we shall study, in some of the following 

 chapters, a few representatives of the great groups of plants, 

 we shall always have to keep in mind that what we really 

 want to find out is what plants are, how and where the differ- 

 ent groups live, how their habits of living are related to the 

 life of other living things, and how they reproduce themselves. 



