OF ARTS AND SCIENCES. 179 



awned ; sterile glume 9-awned. — Our only species of the section 

 Enneapogon. At Parras (1361); 947 Parry & Palmer; 751 and 

 2029 Wright, referred to P. horeale, Griseb., by Torrey (Pacif. Railroad 

 Eep. 4. l.').')). Differing from that Siberian species in its more pilose 

 nodes and ligules, longer and narrower panicles, glumes rather more 

 strongly nerved, flowers smaller and more villous, and the seed broader 

 and more ovate. Its resemblance to P. nigricans, Br. (P. pallidum 



6. B. OLiGOSTACHTA, Torr. Pedicel of sterile glume bearded. — From the 

 Saskatchewan to Texas, Arizona, Southeastern California, and Mexico. See 

 page 177. 



f- ••- Spikes narrowly linear, dense : glumes usually glabrous. 



7. B. poLTSTACHYA, Torr. Flowering and sterile glumes 3-awned, with 

 usually broad lobes between the awns. — From Southern Utah to Texas, 

 Southern California, and Mexico. See page 177. 



t- H- 1- Spikes more loose and slender : lower glumes glabrous. 

 ++ Flowering and sterile glumes bearded at base, 1-awned : peduncle villous. 



8. B. ERIOPODA, Torr. Western Texas and New Mexico. 



** ++ Flowering and sterile glumes naked, 3-awned : peduncle smooth. 



9. B. TRiFiDA, Thurber. Western Texas, New Mexico, and^ Mexico. See 

 page 177. 



10. B. BuRKEi, Scribner, i7ied. Smaller, the spikes shorter, the flowering 

 glume short-villous, and the awns shorter. Western Texas and New Mexico. 

 (167 and 1427 Berlandier, 3440* Curtiss). 



§ 2. Atheropogon, Gray. Spikes several or numerous, usually short, straight, 

 not pectinate, the few (.3 to 12) spikelets often fascicled: the terminal empty 

 glume 3-awned, or more or less reduced and rudimentary. 



11. B. RACEMOSA, Lag. (B. curliiiendula,TovT.) From New York and Penn- 

 sylvania to Wisconsin, and south to Texas, Arizona and Mexico ; South Amer- 

 ica. See page 177. 



12. B. BROMOiDES, Lag. From Western Texas to Arizona and Mexico ; 

 Central America. See page 177. 



13^ B. Havarui, Vasey, ined. Perennial, villous, erect : spikes (4 or 5) half 

 an inch long or less, very silky-villous : lower glume acuminate ; flowering glume 

 3-cleft to the middle, the teeth stout, acuminate, villous ; palet as long, acumi- 

 nate, villous on the back : sterile glume naked, reduced to 3 awns twice longer 

 than the fertile flower, the middle one subulate below, the lateral sometimes 

 villous. — Limpio Mountains, Western Texas ; 753 Wright. 1849 ; Dr. V. 

 Havard, 1881. 



14. B. CHONDROSioiDES, Benth. {Dinebra chondrosioides, HBK., Nov. Gen. 1. 

 173, t. 53.) Mexico. (Not seen.) 



15. B. litigiosa. Lag. (B. porphi/rantha, Wright); and 16. B. elatior, 

 Griseb. West Indies. (The last not seen.) 



17. B. ciLiATA, Griseb., 18. B. i.ophostachta, Griseb., and 19. B. nana, 

 Griseb. South America. (Not seen.) 



20. B. PI LOSA, Benth. {Eutriana pilosa, Kook. i.) Galapagos Islands. 



