PAXirE.E. 163 



2:299 (1841). Serimra Ilassk. Flora, 25 (1842). Bcckeropsis 

 and Ih-ioclncta Fig. »& De Not. Mem. Ace. Torin. (II.) 14:30.5, 

 374 (1854). Macrocltada Steiul. Zoll. Syst. Verz. lud. Archip. 

 6(» (1854). Amphocliaeta Anderss. Vet. Akad. Handl. Stockh. 

 1853, 130 (1855). 



Spikelets 2-ilowered, the lower neuter or etaminate, the terminal 

 one [lorlect or pistillate, solitary or 2-3 together, sessile or nearly 

 so. eaeli one enclosed in an involucre of several usually numerons 

 simple or plumose bristles (probably awnlike branches of the pani- 

 cle), the involucres crowded in a spike or spikelike simple panicle 

 falling off from the main rachis with the spikelet and short pedun- 

 cle, the outer glume shorter or minute, short or nearly e(jual to the 

 floral glume, the palea of the sterile floret smaller, fertile floret 

 sometimes more or less hardened. Stamens 3. Styles distinct or 

 united near the base. Grain enclosed, but not adherent. 



Aninuds or perennials; blades flat. 



There are about 40 species, mostly found in Africa, a few in 

 Asia near the Mediterranean, two in Australia, two or throe in 

 troj)ieal America. Some are cultivated as ornamental grasses. 



It has been at various times proposed to separate several genera 

 from it. G'l/mnothrix was proposed as a genus for those species in 

 which the bristles are perfectly glabrous, but this is not a constant 

 character. 



a. Bristles not plumose (b) 



b. Bristles mostly shorter than the spikolets. . . . 1, 2 

 b. Bristles mostly as long as the spikelet, plant 120-150 cm. 



high 3 



b. Bristles mostly 2-3 times as long as the spikelets. . . 4 



b. Tiristles some shorter some longer than the spikelet. 5, 

 a. liristles more or less plumose (c) 



c. Bristles as long as the spikelet 7 



c. liristles very much longer than the spikelets. ... 8 



1. P. durum. P. crimtnm Scribn. ined. 



A tufted glaucous perennial, 60-120 cm. high. Sheaths loose; 

 blades smooth, long-pointed, 30-40 cm. long, 7-10 mm. wide. 



