87 



any species of the section Bromclica to the genus a matter of ex- 

 treme difficulty for the beginner. 



The author adopts Piper's* view that what has been known as 

 Agrostis alba L. should be called A. palustris Huds., the original 

 name having been founded on what was almost certainly a species 

 of Poa; and A. capillaris L. is in like manner taken up for what 

 has usually been called A. alba var. vulgaris Thurb., the "Rhode 

 Island bent." Apera is regarded as insufficiently distinct from 

 Agrostis and replaced in that genus. Sphenopholis and Koeleria 

 retain the position among the Aveneae to which Professor Hitch- 

 cock has always regarded them as entitled. 



The synonymy is complete for all generic names based on 

 American species ; and all such names, whether valid or in 

 synonymy, are placed on a type-basis. A careful study has been 

 made of each genus with a view to ascertaining which of the spe- 

 cies the author had chiefly in mind, so that the arbitrary method 

 of selecting the first-mentioned valid species as the type is 

 avoided. A brief of the publication of each generic name is 

 given, and in each case the reason for selecting the species taken 

 as the type is stated. The law of priority is strictly applied, and 

 the " nomina conservanda " of the International Rules are in no 

 case maintained. Each genus is technically described, and its 

 scope and distribution indicated. As was inevitable in a publi- 

 cation of the Department of Agriculture, all the economic species 

 under each genus are mentioned, so that the user of the book 

 should be able to refer any of these species to its proper genus. 

 The author's interest in his subject, however, often leads him to 

 extend his treatment to include species of no economic sig- 

 nificance. 



The illustrations with two exceptions (Enchlacua and Coix) 

 are all new, and specially prepared for this work, the habit- 

 drawings by Mary Wright Gill, and the details of the spikelet by 

 Agnes Chase. The figure of Hydrochloa carolinensis on p. 213 

 is an admirable example of the fidelity and accuracy of Mrs. Gill's 

 work. The high cost of paper is doubtless responsible for plac- 

 ing a photographic plate on each side of the inserted leaves. 



*U. S. Dept. Agric. Bull. 692. 1918. 



