INTRODUCTION 



N the main text of this book, 293 kinds of grasses are 

 illustrated and keyed out. These are the common- 

 est and most important species of American grasses 

 — those that the beginner is most apt to meet, and 

 those of importance in farming, gardening, weed 

 control, range and pasture management. In addi- 

 tion to those keyed and illustrated, 91 others are 

 mentioned in connection with closely related species, 

 and their distinguishing features are pointed out. 



The illustrations are all new and have been made from actual 

 specimens. Most of the spikelet drawings were made by camera 

 lucida or projection methods and hence represent individual spikelets, 

 not averages. Drawings of small structures, such as spikelets or their 

 parts, bear measuring scales. These are used to indicate the size of 

 the structures, exactly like the scales used in maps. The scales are 

 marked off into spaces representing millimeters, and the total length 

 of the scale in millimeters is marked. In a few drawings the scale is 

 designed for one particular object, in which case an arrow points to 

 the intended object. 



The maps included in the species drawings represent approximate 

 ranges of the species. Due to lack of exact information, particularly 

 about the arctic and tropical extensions of these ranges, the maps 

 cannot be entirely accurate, but will serve to give a general idea of 

 the geographic area in which a species may occur in favorable habi- 

 tats. The maps are based upon published records, herbarium speci- 

 mens, and the author's personal information. 



Drawings marked with the letter B are the work of Mrs. J. Bardach 

 of Iowa State Teachers College, whose assistance is gratefully acknowl- 

 edged. All others are the work of the author. 



For most species, the period of flowering and fruiting is indicated. 

 These dates cover the entire period during which fully developed and 

 intact inflorescences can be found on the plants. Since grass flowers 

 are rarely used in identification, actual flowering dates are not given. 



Many persons have aided in the production of this little book. 

 First of all, the author wishes to thank his wife and family, for the 

 gift of time, which allowed its completion. The facilities of Iowa State 



