iv PRACTICAL BOTANY 



following it give a more detailed treatment of each of the 

 dominant structures, and the outline sketch of the whole plant 

 now serves as the basis of interpretation of this more special 

 study. Then follow rather brief though adequate chapters 

 dealing with the great groups in the order of their increasing 

 complexity, and these are followed by chapters which treat of 

 broad aspects of plants and their relation to plant industries. 



The material in the book, which is sufficient for a year's 

 course, is so arranged that it can be adjusted to a half-year 

 course when local needs make this desirable. When seasons are 

 favorable it is thought best to follow the order of chapters 

 as given, but seasonal conditions are so diverse in different 

 parts of the country that the teacher is urged to rearrange 

 chapters whenever necessary for adequate illustration of such 

 topics as flowers, seeds, and weeds. If this is done, Chapters I 

 and II may be studied briefly, and then followed by chapters 

 dealing with special topics. 



When the book is used in a half-year course, Chapters I 

 and II should constitute an introduction, and it will usually 

 be found advisable to follow these with Chapters III XI and 

 XXI-XXV. In some cases, however, it will be found advis- 

 able to follow Chapters I and II with Chapters X~XX. In 

 any event, in a half-year course, Chapters XXI-XXV, be- 

 cause of their practical significance, should be assigned for 

 collateral reading if they are not used as the basis of regular 

 class work. 



Not infrequently facts are restated in connection with topics 

 other than those with which they first appear. This seems un- 

 avoidable unless other important considerations are sacrificed, 

 such as securing plasticity in the order of use of the various 

 chapters and avoiding excessive cross reference. 



The number of botanical terms used is as small as is con- 

 sistent with a clear presentation of the facts. The order of 

 the great groups of plants agrees with the most recent usage 

 of the best botanists. In accordance with this usage the bac- 

 teria and the blue-green algae are presented first in the studies 



