1 70 PATAGONIAN EXPEDITIONS I BOTANY. 



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3. Culm 20 cm. ; leaves shorter ; nodes dark, smooth. Panicle depauperate. Awn 4- 



times as long as flower. ameghinoi. 



A$. Awns naked or scabrous or pubescent. 



b. Callus long, several times exceeding the floral diameter. Panicle spreading. 

 c. Crown very long and distinct from the glumella. (Stephanostypa^) 



d. Flowers smooth, cylindraceous, attenuate upwards. Pedicels elongating after 



anthesis. filiculmis. 



d2. Callus villous, shorter than the latterly cleft crown. Awn central, slender. 



Culm slender, 40 cm. formicarum. 



c2. Crown short. Callus ring-like, strong. 



d. Flowers rather large (12 mm.), very tetragonal. Glumes silky. Crown with 

 acute lobed mouth. Awn thrice length of flower. Culm 75 cm., exceeding the 

 glabrous leaves. clarazi. 



d2. Flowers small, 5 mm., glabrous. Awn slender, 10 times as long. Culm 35 cm. ; 



leaves setaceous. Panicle contracted. tenuis. 



c$. Crown subconoid, scarcely constricted off. Flowers mediocre, obsoletely 4-6-angled. 



Callus short, strong. Culm 40 cm. Panicle nodding. manicata. 



c\. Crown none. Flower long, pappose-villous above. Glumes half as long. Culm 30 



cm. Panicle spreading. papposa. 



c$. Crown small, constricted off. Flowers mediocre or small, not over 12 mm. 



d. Crown appressed, ciliolate-fimbriate. Panicle nutant, depauperate. Culm 35 cm. 



ligularis. 



d2. Crown silky. Awn excentric. Leaves setaceous. pampeana. 



d$. Crown with truncate mouth, not appressed, nor laxly-ciliolate. Flowers 6-9 mm. 



setigera. 



b2. Callus short, scarcely exceeding the floral diameter. Crown none or obsolete, not con- 

 stricted off. 

 c. Lower glumella pubescent, pilose or villous. Panicle spike-like. 



d. Glumes lanceolate, 3-5-nerved, violascent. Upper glumella as long as lower, hairy. 



Culm stout, 75 cm. caudata. 



d2. Glumes narrowly linear, obsoletely 1-3 -nerved. Callus villous. Culm slender ; 



spike erect. gynerioides. 



c2. Lower glumella glabrous to scabrid. Crown none. 



d. Upper glumella as long as lower. Callus hairy. Panicle depauperate. Culms 



slender ; leaves convolute, short. rariflora. 



d2. Upper glumella not half as long as lower. Branching of mature panicle repeatedly 

 trichotomous. Leaves setaceous. trickotoma. 



i. S. AMEGHINOI Speg. (Pappostipa). 



Glumes lanceolate, 2-3 times longer than the flower with pappus and 

 joint, 3-5-nerved, greenish-hyaline. Flower spindle-shaped, villous, but 

 dorsally glabrous in part; calhis slightly exceeding the diameter of the 

 flower, villous with a ventral foveola. Awn rigid, 4 times as long as the 

 flower, pappose-villous. No crown. Culms simple, 1025 cm., with 



