156 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



The name Setaria, applied to this genus by many authors, has been 

 replaced by CliaetocMoa because the former name was applied to a 

 genus of lichens by Acharius and by Michaux at a date earlier than 

 that of its application to the grass genus (see synonymy in the 

 technical description). 



There are about 60 species of Chaetocliloa, 26 in North America, 

 about 15 more in South America, the remainder in the warmer parts 

 of the Eastern Hemisphere. 



The text figures are natural size. 



DESCRIPTION OF THE GENUS AND SPECIES. 

 CHAETOCHLOA Scribn. 



Setaria Beauv. Ess. Agrost. 51. pi. IS. f. 3. 1812. Not Setaria Ach. 1798, 1 nor Michx. 

 1803. Fourteen species are listed, £. viridis being illustrated. Panicum virideli., upon 

 which the illustrated species is based, is taken as the type. 



Panicum subgenus Ptychophyllum A. Br. Tnd. Sem. Hort. Berol. App. 1855. The 

 author mentions the plicate-leaved species of Panicum that had been long cultivated 

 in botanic gardens under the name of P. plicatum Auct. He describes Ptychophyllum 

 as a subgenus of Panicum and notes its close affinity to the subgenus Setaria. Ten 

 species are described, the first of which is Panicum plicatum Lam. This species 

 may be taken as the type. 



Chaetochloa Scribn. U. S. Dept. Agr. Div. Agrost. Bull. 4: 38. 1897. Scribner 

 substitutes the name Chaetochloa for Setaria Beauv., not Ach. The type is the same 

 as for Setaria, namely Panicum viride L. 



Some of our species of Chaetochloa have been referred to Ixophorus Schlecht. and 

 to Chamaeraphis R. Br., but the types of those genera are not congeneric with the 

 type of Chaetochloa. 



DESCRIPTION. 



Annual or perennial grasses with flat or rarely involute blades, and narrow, 

 usually spikelike, or rarely open panicles. Culms simple or usually branched at 

 the base and sometimes at the middle nodes, the branches from the latter appressed 

 or ascending, bearing secondary panicles, these usually smaller than those of the 

 primary culms. Spikelets lanceolate or elliptic, usually turgid, rarely globose, 

 sessile or short-pediceled, single or in clusters, some or all subtended by one to several 

 bristles (sterile branchlets), deciduous, falling free from the bristles, awnless, the main 

 branches of the panicle usually short, rarely elongate. First glume broad, usually less 

 than half the length of the spikelet, 3 to 5 nerved. Second glume and sterile lemma 

 equal or the former shorter, several-nerved. Fertile lemma coriaceous or indurate, 

 smooth or rugose. 



KEY TO THE SPECIES. 



Blades narrowly elliptic, plaited; bristles below only a part of the spikelets, rarely 

 below all. Subgenus Ptychophyllum. 



Plants annual; blades usually less than 2 cm. wide 1 . C. barbata. 



Plants perennial; blades usually more than 3 cm. wide. 

 Panicle of numerous approximate, more or Ipss 1-sided racemes, spikelet-bearing 

 to the base, 2 to 5 cm. long, rarely the lower much longer. .2. C. poiretiana. 

 Panicle of more or less fascicled branches, not or scarcely 1-sided, some of them 

 elongate and naked at base. 

 Branches of panicle as much as 10 cm. long; bristles usually not over twice as 

 long as the spikelets, inconspicuous; blades as much as 6 cm. wide. 



3. C. palmifolia. 



Branches of panicle slender, finally spreading, as much as 20 cm. long; bristles 



as much as 15 mm. long; blades as much as 10 cm. wide. .4. C. sulcata. 



1 See note at bottom of p. 208. 



