THE NORTH AMEEICAN SPECIES OF ECHINOCHLOA. 



By A. S. Hitchcock. 



INTRODUCTION. 



In earlier works this group of grasses was usually included as a 

 section in the great genus Panicum. The species form a compact 

 group which according to the modern concept is assigned to generic 

 rank. 



There are seven species of EchinocTiloa in North America, two of 

 them introduced from the Old World and a third introduced as well 

 as native. Besides these species there are at least three in the Old 

 World. Although the genus itself is well marked, some of the 

 species are exceedingly variable and not easily distinguished from 

 each other. 



A variety of one species, EchinocTiloa crusgalli edulis, is occasionally 

 cultivated in the United States for forage under the name of Japanese 

 barnyard millet, and at one time was advertised by seedsmen as 

 billion dollar grass. 



The text figures are natural size. 



DESCRIPTION OF THE GENUS AND SPECIES. 



ECHINOCHLOA Beauv. 



Echinochloa Beauv. Ess. Agrost. 53. pi. 11. f. 11. 1812. The type species is Panicum 

 crusgalli, the one figured. Beauvois mentions several species in the text under 

 Panicum and lists them under Echinochloa in the index. 



DESCRIPTION. 



Annual or perennial, coarse, often succulent grasses with linear flat blades and 

 usually narrow panicles consisting of several spikelike racemes along a main axis. 

 Spikelets plano-convex, often spiny-hispid, subsessile, in pairs or in irregular clusters 

 crowded on one side of the panicle branches. First glume about half as long as the 

 spikelet, pointed. Second glume and sterile lemma equal, stiffly hispidulous on 

 the nerves, usually scabrous on the internerves, pointed, mucronate, or the glume 

 short-awned, the lemma mucronate or awned, sometimes conspicuously so, inclosing 

 a membranaceous palea and sometimes a staminate flower. Fruit plano-convex, the 

 lemma and palea smooth and shining, abruptly acuminate-pointed, the lemma mar- 

 gins inrolled below, flat above, the apex of the palea not inclosed. 



The genus differs from Panicum in the awned glumes (the first awnless in some 

 species) and sterile lemma and the pointed fertile lemma. The awns are reduced 

 to mucros or points in E. colonum, but the habit of the plant and the structure of 

 the inflorescence show the species to be closely allied to the others. 



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