1 76 PATAGONIAN EXPEDITIONS I BOTANY. 



culm 3, involute. Panicle spike-like, 6-20 cm. long ; rays in pairs bear- 

 ing 1-3 spikelets. Empty glumes subequal, hyaline, acuminate, 16 mm. 

 long, 3 and 5~7-nerved. Flowering glume silky, 5-nerved, 8-12 mm. 

 long, with short callus and 2-toothed hairy apex; its awn 3-4 cm., genicu- 

 late, twisted, plumose, with many long hairs at its base. 

 (Argentina) ; S. Patagon. (Dusen). 



19. S. TENUIS Phil. 1870. (S. argentina Speg. 1896. S. neesiana 



O. Ktze. 1896, non Trin.) 



Glumes linear-lanceolate, 2-3 times longer than the flower, i-3-nerved, 

 hyaline to violascent. Flowers subfusoid, terete, smooth. Crown small, 

 turbinate, with a ciliolate circle. Callus 2-3 times as long as the floral 

 diameter, white-villous. Awn persistent, slender, 8-12 times longer than 

 the flower, jointed about the lowest fourth, scarcely pubescent. Culms 

 15-45 cm -> much exceeding the setaceous or rush-like rough leaves. 

 Panicle narrow, depauperate. 



N. Patagon. in dry and mountain plains by Rio Negro, and northwards 

 in Argentina (also in California). 



20. S. TENUISSIMA Trin. (S. mendocina Ph.; S. oreophila Speg.) 



Glumes lanceolate, 3-4 times longer than the flower, 3-nerved, hyaline, 

 tending to violet. Flower long, small, dorsally subgibbous, laterally 

 compressed, glabrous, very delicately rough. Callus as long as the flower 

 is broad, villous, acute. Crown small, boss-like, ciliolate. Awn persistent, 

 very slender, 25 times as long as the flower. Citlms 30-50 cm., little 

 exceeding the capillary-setaceous, scabrid leaves. Panicle vaginate, con- 

 tracted. 



(Argentina) ; N. Patagon., by Rio Negro, on dry sandy plains and 

 dunes. 



21. S. TRICHOTOMA Nees. (Hack, sub Nasella]. 



Glumes ovate-lanceolate, 3-4 times as long as the 'flower, 3-nerved, 

 purplish. Flower obovate, dorsally gibbous, glabrous to slightly rough. 

 Crown none. Callus very short, white-villous. Awn persistent, 8-15 

 times as long as the flower. Culms slender, 15-50 cm., at first as long 

 as the scabrid setaceous leaves ; the uppermost internode at length elon- 

 gating produces a large lax panicle with trichotomous rays. 



(Argentina, etc.) ; N. Patagon., over pampas, by Rio Negro. 



