THE NOETH AMEEICAN SPECIES OF CHAETOCHLOA. 



By A. S. Hitchcock. 



INTRODUCTION. 



The genus Chaetochloa is closely allied to Panicum, from which it 

 is separated technically by the presence of bristle-like sterile branch- 

 lets below the spikelets. Two species, introduced from Europe, are 

 common weeds in the eastern states. One, C. lutescens (Setaria 

 glauca of authors), with a dense cylindric spikelike panicle or head, 

 and yellow bristles, is called yellow foxtail or pigeon grass. The other, 

 green foxtail ( C. viridis) , has green heads. The bristly head or narrow 

 panicle is characteristic of most of the species of the genus. One 

 species, C. italica (Setaria italica), is cultivated under the name of 

 millet or foxtail millet. Of this there are many varieties, such as 

 Hungarian grass, German millet, and Golden Wonder. To these the 

 general term millet is applied, a name which should not be confused 

 with the common millet of Europe (Panicum miliaceum) , cultivated 

 occasionally in the United States for forage under the name of broom- 

 corn millet, proso millet, and hog millet. The North American 

 species of Chaetochloa were revised in 1900 by Scribner and Merrill. 1 



The allies of Panicum jpalmifolium are here included under Chaeto- 

 cMoa as a subgenus (Ptychoj)hyllum) . They are tropical species with 

 broad plaited blades. Some are cultivated in greenhouses under the 

 name of palm grass, because of the leaves which resemble those of a 

 young palm. 



In a small group of species of Panicum (forming the subgenus 

 Paurochaetium 2 ) the ultimate branchlets are produced beyond the 

 few to several spikelets as minute bristles. In ChaetocMoa proper 

 each spikelet is subtended by one or more bristles. In the subgenus 

 Ptychophyllum usually only the terminal of the one to few spikelets 

 on a branchlet is subtended by the bristle. Panicum and ChaetocMoa 

 thus closely approach each other. The species of the subgenera 

 Paurochaetium and Ptychophyllum are included respectively in 

 Panicum and Chaetochloa because, all their characters taken into 

 consideration, they show closer relationship to other species in 

 Panicum and Chaetochloa, respectively, than they do to each other. 



1 U. S. Dept. Agr. Div. Agrost. Bull. 21. 1900. 



2 Contr. U. S. Nat. Herb. 15: 22. 1910. 



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