10 Bulletin VII. 1. 



26. Empty glumes not awn-pointed, falling with the fruiting 



glume; palea none, flowering glume awned on the back. 

 23. Alopecurus. 



27. Flowering glume one-nerved, longer than the unequal 



empty ones 24. Sporobolus. 



27. Flowering glume three- to five-nerved, shorter than the 



empty ones 28 



28. Flowering glume raised on a distinct, naked internode of the 



rachilla; stamen one 25. Cinna. 



28. Flowering glume not raised on a distinct internode of the 



rachilla; stamens three 29 



29. Callus with long hairs (at least half as long as the flowering 



glume); rachilla continued beyond the palea 



27. Calamagrostis. 



29. Callus naked (or with a few very short hairs only); rachilla 



not prolonged behind the palea .... 26. Agrostis. 



30. Flowering glumes usually shorter than the empty ones, 



bearing a twisted or geniculate awn (some cultivated 

 forms excepted) on the back or between the teeth of the 

 bifid apex (Tribe Avene/e) 31 



30. Flowering glumes usually longer than the empty ones, awn- 



less or bearing a straight (rarely bent) awn at or just 

 below the entire or two-toothed apex (Tribe Festuce.e) 44 



31. Flowering glumes thin and scarious, apex irregularly den- 



ticulate, slender-awned on the back from near the base 

 29. Deschampsia. 



31. Flowering glumes of firmer texture, entire, two-toothed or 



two-cleft at the apex 32 



32. Spikelets strictly two-flowered, one of the flowers staminate ;^;^ 

 32. Spikelets two to many-flowered, all the flowers hermaphro- 

 dite or the uppermost imperfect or rudimentary .... 34 



S^. Lower flower staminate, its glume long-awned on the back 

 from near the base ...... 32. Arrhenatherum. 



S3. Lower flower hermaphrodite, its glume awnless. 28. Holcus. 



34. Flowering glumes thin and hyaline, carinate, awned from 

 near the apex 30. Trisetum. 



34. Flowering glumes herbaceo-chartaceous, rounded on the 



back, two-toothed or bifld at apex, awned between the 

 teeth 35 



35. Awn terete, proceeding from the mid-nerve only. 31. Avena. 



35. Awn flat below, formed by the union of the three middle 



nerves of the glumes 33. Danthonia. 



36. Spikelets sessile or nearly so, in two rows along one side of 



the continuous axis forming unila,teral racemes or spikes, 

 these racemed or digitate. (Tribe Chloride.^) .... 37 



36. Spikelets in opposite rows along a jointed rachis, forming a 



two-sided or equilateral, terminal spike. (Tribe Horde.e) 59 



37. Spikes terminal or nearly so, digitate or whorled . . . . ^S 



37. Spikes (or one-sided racemes) scattered along a common 



axis (usually racemed) 41 



38. Spikes slender, one hermaphrodite flower and a sterile 



rudiment of a second flower in each spikelet 39 



