80 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



10. ECHINOCHLOA Beauv. 



Sheaths glabrous; awns rarely over 3 em. long; panicle rarely over 20 cm. long, not 



drooping 1. E. crusgalli 



Sheaths hirsute ; awns 3-5 cm. long; panicle drooping, commonly 30-40 cm. long. 



2. E. walteri. 



1. Echinochloa crusgalli (L.) Beauv. Barnyard grass. Cocksfur. 

 Moist low open ground; common; an introduced weed. Aug. -Sept. Throughout 



the U. S'., oxcept in the northern tier of states; native of Eur. (I'amcum crusgalli L.) 



2. Echinochloa walteri (Puish) Nash. 



In swales; Potomac flats and southward; infrequent. Aug.-Sept. Atlantic 

 Coastal Plain, and about the head of Lake Michigan. (Panicum walteri Pursh; P. 

 Crusgalli hispidum A. Gray.) 



11. CHAETOCHLOA Scribn. 



Plants perennial by short knotty rootstocks 1. C. geniculata. 



Plants annual. 



Bristles downwardly barbed 3. C. verticillata. 



Bristles upwardly barbed . 



Bristles 5 or more in each cluster; spikes yellowish 2. C. lutescens. 



Bristles 1-3 in each cluster; spikes «;reen or purplish. 

 Spikelet articulate below the glumes, the complete spikelet shelling out, 



leaving a cuplike receptacle 4. C. viridis. 



Spikelet articulate above the glumes, only the fruit shelling out, leaving the 

 persistent glumes and sterile lemma 5. C. italica. 



1. Chaetochloa geniculata (Lam.) Millsp. & Chase. 



Moist meadows and along ditches; frequent. Sept. Eastern U. S. (Setaria 

 imberbis Roem, & Schult.; C. imberbis Scribn.) 



2. Chaetochloa lutescens (Weigel) Stuntz. Yellow foxtail. 

 Open waste and cultivated ground everywhere. July-Sept. Common east of the 



Rocky Mts., rare on the Paciiic Coast; introduced from Eur. 



A troublesome weed in lawns and gardens. In mowed lawns the culms become 

 prostrate and fruit when 10-20 cm. long. (Setaria glauca and Chaetochloa glauca of 

 authors.) 



3. Chaetochloa verticillata (L.) Scribn. 



Open waste ground; uncommon. July-Aug. Eastern and middle states. Intro- 

 duced from Eur. (Setaria verticillata Beauv.) 



4. Chaetochloa viridis (L.) Scribn. Green foxtail. 

 Open waste ground and river flats; frequent. June-Aug. Throughout the U. S.; 



introduced from Eur. (Setaria viridis Beauv.) 

 Not an aggressive weed in this region. 



5. Chaetochloa italica (L.) Scribn. Millet. 

 Dumping grounds and along railroads. July. Throughout the U. S., except in the 



mountains, as an escape from cultivation; native of Eur. (Setaria italica Roem. & 

 Schult.) 



Plants growing spontaneously vary in size from 30 cm. or less to 1.5 meters tall. 



12. CENCHEUS L. 



1. Cenchrus pauciflorus Benth. Sandbur. 



Sandy ground, along railroads and trolley tracks to the eastward; common in the 

 vicinity of Bennings. July Sept. Throughout the U. S. (C. tribuloides of Ward's 

 Flora; C. carolinianus of recent manuals, not Walt.) 



