UNITED STATES DEPARTMENT OF AGRICULTURE 
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. Hitcucocrk, Systematic Agrostologist. 
CONTENTS. 
Page Page. 
Scope and plan of the work..--.......-....-- 1 | Descriptions of the genera—Continued. 
Poaceae, the grass family...................- 5 6. Nazieae, the curly-mesquite tribe ..... 165 
Descriptions of the subfamilies and keys to 7. Chlorideae, the grama tribe -......-.- 171 
BRANES SE cn eSe NIL 5h Ss 6 8. Phalarideae, the canary-grass tribe ... 199 
Descriptions of the tribes and keys to the 9. Oryzeae, the rice tribe ............---- 204 
SUEDE onc 3p - Sed Ges SSeS ees aes eee ete 8 10. Zizanieae, the Indian-rice tribe .-..--- 206 
Descriptions of the genera...............-... 22 11. Melinideae, the molasses-grass tribe... 212 
1. Bamboseae, the bamboo tribe -...._.. 22 12. Paniceae, the millet tribe .....-.-.--- 213: 
z. Festuceae, the fescue tribe -...-.....- 24 13. Andropogoneae, the sorghum tribe... 252 
3. Hordeae, the barley tribe ............ 87 14. Tripsaceae, the corn tribe ............ 280 
4. Aveneae, the oat tribe ................ 106 | List of new species and new names ......... 288 
5 Agrostideae, the timothy trine ....._.- LTS ln exces enee cen itee cence Paisicmeehaccsice estes 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 
97769°—Bull. 772—20-——1 
