UNITED STATES DEPARTMENT OF AGRICULTURE 



^^ BULLETIN No. 772 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



March 20, 1920 



THE GENERA OF GRASSES OF THE UNITED STATES, 

 WITH SPECIAL REFERENCE TO THE ECONOMIC 

 SPECIES. 



By A. S. HITCHCOCK, Systematic Agrostologist. 



CONTENTS. 



Page. 



Scope and plan of the work 1 



Poaceae, the grass family 5 



Descriptions of the subfamilies and keys to 



the tribes 6 



Descriptions of the tribes and keys to the 



genera 8 



Descriptions of the genera 22 



1. Bamboscae, the bamboo tribe 22 



2. Festuceae, the fescue tribe 24 



3. Hordeae, the barley tribe 87 



4. Aveneae, the oat tribe 106 



5 Agrostideae, the timothy tribe 121 



Page. 

 Descriptions of the genera Continued. 



6. Nazieae, the curly-mesquite tribe 1G5 



7. Chlorideae, the grama tribe 171 



8. Phalarideae, the canary-grass tribe ... 1C9 



9. Oryzeae, the rice tribe 201 



10. Zizanieae, the Indian-rice tribe 206 



11. Mclinideae, the molasses-grass tribe . . 212 



12. Paniceae, the millet tribe 213 



13. Andropogoneae, the sorghum tribe... 252 



14. Tripsaceae, the corn tribe 280 



List of new species and new names 288 



Index ... 289 





SCOPE AND PLAN OF THE WORK. 



The present bulletin describes all the genera of grasses that include 

 species that are native, have been introduced, or are cultivated in the 

 United States. Under each genus are given the species that are 

 of economic importance, either as useful or harmful grasses. Of all 

 grasses the grains are of the greatest importance. Chief among other 

 useful grasses are those that are cultivated for meadow or pasture 

 and those indigenous species which furnish forage upon the native 

 pasture or ranges. Other important grasses are the sugar-producing 

 species, those used in broom or paper making, and the ornamental 

 species. 



It is intended to give under each genus the botanical information 

 concerning all our grasses that are conspicuous enough to have at- 

 tracted the attention of agriculturists. The keys to the tribes and 



97700 Bull. 77220 1 





