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14. Perianth none or of dry scales, these often in 2 ranks, 
16. Stems terete, jointed, mostly hollow; leaves 2 -ranked; anthers versatile, 
17. Spikelets 1-many-flowered, laterally compressed; articulation above the 
glumes, 
18. Spikelets sessile on a continuous rhachis, 
19. Spikelets opposite; spike terminal, solitary, 
20. Spike 1.2-1. 5 mm. thick 19. Lepturus repens var. repens 
20. Spike 1.7-2 mm. thick 20. L. repens var. occidentals 
19. Spikelets on only one side of the rhachis; spikes usually several, 
digitate or racemose, 
21. Spikelets with more than 1 perfect flower, 
22. Rhachis of spike extending beyond the spikelets 
15. Dactylo ctenium aegyptium 
22. Rhachis of spike not prolonged 17. Eleusine indica 
21. Spikelets with only 1 of the florets perfect, 
23. Spikelets without additional modified florets; rhachilla pro- 
longed behind the palea 14. Cynodon Dactylon 
23. Spikelets with 1 or more upper modified florets 
. ..13. Chloris inf lata 
18. Spikelets pediceled in open panicles; lemmas 3 -nerved 
18. Eragrostis amabilis 
17. Spikelets with 1 perfect terminal floret and 1 staminate or rudimentary 
one below; spikelets dorsally compressed; articulation below the 
spikelet, 
24. Glumes and sterile lemma membranous, 
25. Spikelets borne from the one furrowed side of the rhachis; plant 
creeping 23. Thuarea involuta 
25. Spikelets not so; plant erect, 
26. Spikelets subtended or surrounded by bristles or spines, 
27. Bristles connate at base, falling with the burlike spikelet, 
28. Spikelets 5-6 mm. long; involucre pilose; first glume pres- 
ent 12. Cenchrus echinatus 
28. Spikelets 4 mm. long; involucre puberulous; first glume 
wanting 11. C. Brownii 
27. Bristles distinct, persisting on axis; spikelets discoid, falling 
free of the bristles 21. Setaria verticillata 
26. Spikelets not subtended by bristles, 
29. Glumes and sterile lemma awned; spikelets long-silky 
25. Tricholaena repens 
29. Glumes and sterile awnless, 
30. Spikelets long-silky, in panicles; fruit lanceolate, acumi- 
nate 24. Tricachne insularis 
30. Spikelets short pubescent or glabrous; fruit elliptic; ra- 
cemes quite or nearly digitate 16. Digitaria pruriens 
24. Glumes indurate; fertile lemma and palea hyaline or membranous; 
sterile lemma like the fertile one, 
31. Spikelets unisexual, in separate inflorescences; individual ovaries 
naked 25. Zea Mays 
31. Spikelets in pairs or threes, one sessile and perfect, the others pedi- 
celled and staminate 22. Sorghum bicolor var. technicum 
