AX DROrOGONKAE 



29 



it can be controlled quite readily. It has its advantages also 

 as a pasture grass for milch cows, and a really good grass 

 for this purpose in New Mexico is hard to find. It is by no 

 means an excellent one but is better than any other so far 

 tvied. It will only grow at the lower and hotter levels, but 

 here it does well, and the prejudice against it is very largely 

 unwarranted, so long as it is not allowed to go to seed. As 

 a hay crop it cannot coni];are with alfalfa. 



Tribe I. ANDROPOGONEAE. 



Spikelets sessile and pedicellate, the former 

 perfect, the latter empty, staminate, or 

 wanting. 

 First empty glume of the sessile spikelet not 

 balsam bearing. 

 Sessile spikelets all alike, throughout the 

 inflorescence. 

 Racemes single: a cup-shaped appendage 

 .at the tip of the clavate rachis joints. 

 Racemes in pairs or more numerous; 

 rachis joints not appendaged. 

 Rachis joints and pedicels sulcate and 



translucent. 

 Rachis joints not sulcate nor translu- 

 cent. 

 Some of the racemes sessile. 

 All of the racemes pedunculate. 

 Pedicellate spikelet wanting. 

 Pedicellate spikelet present. 

 Lower spikelet different from the others. 

 First empty glume of the sessile spikelet 

 balsam bearing. 

 Spikelet.'^ all pedicellate, the long pedicellate 

 one perfect, the short pedicellate one stam- 

 inate. 



1. SCHIZACHTRIUXr. 



2. amphilophis. 



3. .axdropogox 



4. sorghasthum. 



5. Sorghum. 



•). Heteropooon. 



7. Elionuruj. 



S. Trachypogon. 



I SCHIZACHYRIUM Xees. Sage-grass 



Pedicels clothed with long silky hairs. 



Peduncles long and slender, much e.vserted, 

 twisted below the spike; spikes single. 

 Peduncles not much exserted from the 

 sheaths. 

 Hairs on the pedicels very few or none, short 

 when pie=ent. 



S. uco-mexicanum. 

 S. scoparium. 

 S. cinhatum. 



I. Schizachyrlum neo-mexicanum Nash. In dry rocky sit- 

 uations in low mountains in the Upper Sonoran Zone. It is probably 

 too near the v.oyt to re niaintnineil. Further study will determine. 



