POACEAE. 



Anthers 2-celled, versatile. Ovary 1-celled, 1-ovuled. Styles 1-3, com- 

 monly 2 and lateral. Stigmas hairy or plumose. Fruit a seed-like grain 

 (caryopsis). Endosperm starchy. About 3500 species widely distributed 

 throughout the world, growing in water and on all kinds of soil. Those 

 yielding food-grains are called cereals. The species are more numerous in 

 tropical countries, while the number of individuals is much greater in tem- 

 perate regions, often forming extended areas of turf. 



A. Spikelets articulated below the lowest (empty) scales, 1-flowered or 2-flowered. 



a. First scale of the spikelet the longest, enclosing the others. 



Inflorescence of clustered racemes. 

 Inflorescence paniculate, decompound. 



b. First scale smaller than the others, or wanting. (PANI- 



CEAE.) 



1. Spikelets not sunken in the rachis of a spike. 



* Spikelets naked, not subtended by bristles or by an 



involucre. 



t Outer scales of the spikelets awnless. 

 Spikelets obtuse, in spike-like racemes. 

 Spikelets acute, in spike-like racemes, or 



panicled. 



Second scale not saccate. 

 Second scale saccate at base, large, many- 

 nerved. 



Spikelets long-silky ; fruiting scale lan- 

 ceolate. 

 Spikelets short-pubescent or glabrous ; 



fruiting scale elliptic, 

 tt Outer scales of the spikelets awned. 

 Third scale with the longest awn. 

 Third scale with the shortest awn. 

 ** Spikelets subtended by 1 or more bristles or by an 



involucre. 



Spikelets subtended by persistent bristles. 

 Spikelets subtended by a 2-valved spiny involucre, 

 deciduous with it. 



2. Spikelets sunken in the thick rachis of a flat spike. 

 B. Spikelets articulated above the empty scales or between the 



flowering scales, 1-many-flowered. 



a. Spikelets panicled or racemed, or if spicate, not in depres- 

 sions of the rachis of the spike. 

 1. Spikelets not in 2-rowed secund spikes. 



* Spikelets 1-flowered. 



t Empty scales 4. (PHALARIDEAE. ) 

 tt Empty scales 2. (AGROSTIDEAE.) 



Empty scales of the spikelet persistent, the 



flowering scales deciduous. 

 Empty scales awned. 

 Empty scales awnless. 

 Spikelets wholly deciduous at maturity. 

 ** Spikelets 2-many-flowered. 



Flowering scales shorter than the empty ones, the 



awn dorsal, usually bent. (AVEXEAE.) 

 Flowering scales mostly longer than the empty 

 ones, the awn, if present, straight, terminal. 

 (FESTUCEAE.) 



Flowering scales long-hairy ; very tall grass. 

 Flowering scales not long-hairy ; low grasses. 

 Flowering scales 1-3-nerved. 

 Panicle-branches distichous. 

 Panicle-branches spirally arranged. 

 Flowering scales 5-many-nerved. 

 Flowering scales cordate. 

 Flowering scales not cordate. 



Stigmas borne at or near the apex 



of the ovary. 

 Flowering scales keeled on the 



back. 

 Flowering scales rounded on the 



back, at least below. 

 Inflorescence a short-branched 



panicle. 



Inflorescence a simple or 

 branched spike. 



( ANDROPOGONEAE. ) 



1. Andropogon. 



2. Holcus. 



3. Paspalum. 



4. Panlcum. 



5. Valota. 



6. Syntherisma, 



1. Echinochloa. 



8. Oplismenus. 



9. Chaetochloa. 



10. Cenchrus. 



11. Stenotaphrum. 



12. Phalaris. 



13. Phleum. 



14. Sporobolus. 



15. Polypogon. 



16. Avena. 



17. Arundo. 



18. Koehleria. 



19. Eragrostis. 



20. Briza. 



21. Poo. 



22. Scleropoa. 



23. Desmazeria. 



