(ikASSES OF OHIO 207 



KEY TO THE GENERA OF OHIO GRASSES. 



The number after the generic name refers to the list number. 



1. Spikelets in panicles or racemes, or in spike-like racemes, not in definite 

 rows on the branches of the inflorescence, usually on distinct pedicles of 

 varying lengths. 2 



1. Spikelets borne in definite rows (usually 2 rows) on a simple inflorescence 

 or on the branches of a compound inflorescence. 51 



2. Spikelets not enclosed in a prickly bur. 3 



2. Spikelets enclosed in a prickly bur; an annual grass. Cenchrus. (59) 



3. Spikelets articulated above the empty glumes. 4 



3. Spikelets articulated below the empty glumes, which are occasionally minute. 38 



4. Spikelets with 2 to many perfect flowers. 5 



4. Spikelets with but 1 perfect flower, rarely with 1 or 2 additional staminate 

 flowers. 23 



5. Flowering glumes as long or longer than the empty glumes, unawned or with 

 a straight awn from the apex. 6 



5. Flowering glumes generally shorter than the empty glumes, usually with a 

 bent or twisted awn on the back below the apex of the lemma. 18. 



6. Rachilla of the spikelet naked or with hairs shorter than the flowering glumes. 7 



6. Rachilla with hairs longer than the flowering glumes ; very tall stout grasses ; 

 lowest flower staminate, the others perfect. Phragmitcs. (14) 



7. Spikelets all alike. 8 



7. Spikelets of 2 kinds 'in a dense spike-like inflorescence, the fertile 1-3-flowered, 

 the lower spikelets of the inflorescence clusters consisting of empty glumes. 



Cynosurus. (13) 



8. Lemma 5-many-nerved. 9 



8. Lemma 3-1-nerved. 14 



9. Spikelets not in dense 1-sided clusters on the inflorescence. 10 



9. Spikelets nearly sessile in dense 1-sided clusters at the ends of the panicle 

 branches. Dactylis (6) 



10. Spikelets with the upper flowering glumes like the lower fertile ones, or if 

 empty not enfolding each other. 11 



10. Spikelets with the upper flowering glumes empty and enfolding each other 

 in a club-shaped mass. Melica (2) 



11. Lemma keeled; base of the flowers often with webby hairs. Poa. (5) 



11. Lemma rounded en the back or keeled only at the summit. 12 



12. Xerves of the lemma 5-7, prominent, parallel; style terminal; spikelets com- 

 pressed cylindric, or little flattened. Panicularia. (4) 



12. Xerves of the lemma not prominent. 13 



13. Stigmas arising below the apex of the ovulary ; lemma 2-toothed. 



Bromus. (l) 



13. Stigmas at or near the apex of the ovulary; lemma entire. Fcstuca. (3) 



—14— 



14. Flowering glumes not coriaceous when mature, grain beakless and not ex- 

 serted. 15 



14. Flowering glumes coriaceous in fruit, grain beaked and exserted ; upper 2-4 

 lemmas empty. Korycarpus. (10) 



15. Lateral nerves of the lemma glabrous. 16. 



15. Lateral nerves of the lemma pilose. 17 



16. Panicle open; spikelets 3-many-flowered. Eragrostis. (7) 

 16. Panicle dense and spike-like, spikelets 2-4-rlowered. Koeletia. (9)' 



