106 POACEAE 



Panicle usually 1-3 cm. thick : bristles usually purple : spikelets 



■2.5-3 mm. long. 9. C. Italica. 



Flowering scale shining, very hard in fruit, smooth : plants usually 



2-4 m. tall. 10. C. macinn. 



** Panicle slender, loose, narrow, often interrupted below. 



Spikelets about 3 mm. long. 15. C. villosissima. 



Spikelets about 2 mm. long. 16. C. Grisebachii. 



b. Second scale ma.nifestly shorter than the flowering scale. 

 Spikelets less than 3 mm. long. 



Panicle loose, often interrupted below, usually narrowed at the summit. 

 Spikelets elliptic to ovate. 



Panicle long-attenuate at the apex. 18. C. caiidata. 



Panicle narrowed at the apex, but not long-attenuate. 



Leaf-blades 1 cm. wide or less : stems usually slender. 16. C. Grisebachii. 



Leaf-blades 1.5-2 cm. wide: stems usually stout. 17. C. pohjslachya. 



Spikelets hemispheric. 13. C. maa'ostachya. 



Panicle dense, of the same diameter throughout. 



Flowering scale very coarsely undulate-rugose : panicles with many 



bristles. 11. C. corrugata. 



Flowering scale finely transverse-rugose : panicles with rather few 



bristles. 12. C. composita. 



Spikelets 3 mm. long or more. 



Panicle dense, of equal diameter throughout, 1 cm. thick or less, ex- 

 clusive of the bristles. 12. C. composita. 

 Panicle loose, narrowed at the summit, 2-4 cm. in diameter, exclusive 

 of the bristles. 

 Leaf-blades 1-2 cm. wide, glabrous. 14. C. macrotipcrma. 

 Leaf-blades 6-8 mm. wide, pubescent on both surfaces with spread- 

 ing hairs. 15. C. villosissima. 



1. Chaetochloa glauca (L. ) Scribn. Annual. Stems tufted, 3-12 dm. tall, branch- 

 ing at the base : leaf-sheaths glabrous, loose, compressed ; blades 1.5 dm. long or less, 4-8 

 mm. wide, glaucous, at least the lower ones pilose near the base on the upper surface : ra- 

 cemes dense, about 1 cm. in diameter, the rachis pubescent, 2-10 cm. long: spikelet& 

 broadly ovoid, 3 mm. long and 2 mm. wide, the acute flowering scale striate, coarsely 

 transversely rugose. [Setaria gluuca Beauv. ] 



In cultivated grounds and waste places nearly throughout North America. Naturalized from 

 Europe. Summer and fall. 



2. Chaetochloa imberbis ( Poir. ) Scribn. Perennial. Stems tufted, 3-7 dm. tall, 

 from rootstocks, slender, compressed, rough below the raceme : leaf-sheaths glabrous, com- 

 pressed ; blades 1-3 dm. long, 3-7 mm. wide, tlie upper surface often with a few long hairs 

 at the base : racemes dense, spike-like, 2-5 cm. long, nearly 1 cm. in diameter, exclusive 

 of the bristles, the rachis pubescent : bristles 5-10 mm. long: spikelets ovoid, acute, 2-2.5 

 mm. long, the flowering scale acute, striate, finely transversely rugose. {^Setaria laevigata 

 Chapm. in part. ] 



In moist soil. New Jersey, Kansas and Missouri to Florida and Texas. Also in tropical America. 

 Spring to fall. 



3 Chaetochloa versicolor Bicknell. Perennial. Stems 6-12 dm. long, ascending : 

 leaf -sheaths compressed, keeled, smooth and glabrous ; blades long and narrow, 1-3.5 dm. 

 long, 2-6 mm. wide, pale green or glaucous, glabrous : spike-like raceme long-exserted, 

 ratlier slender, 2-7 cm. long, about 1.5 cm. in diameter: bristles in two nearly equal clus- 

 ters of 5 each, very slender, 0-10 mm. long : spikelets usually single, about 2.5 mm. long 

 and 1.25 mm. wide, the first and second scales 3-nerved, the fourth scale purple-tipped. 

 \_Panicum laevigatum JLW., not Lam. Sefarin laevigata Chupm. in part.] 



Along borders of salt or brackish marshes, Massachusetts to Florida. Summer and fall. 



4. Chaetochloa occidentalis Nash. Perennial. Stems from a stout branching root- 

 stock, 3-8 dm. tall : leaf-sheaths compressed, keeled, smooth and glabrous ; blades erect, 

 firm, 1.5 dm. long or less, 5-7 mm. wide, glabrous : spike-like racemes 3-5 cm. long, 1.5- 

 2 cm. in diameter : bristles green : spikelets a little less than 3 mm. long, the flowering 

 scale strongly transversely rugose, elliptic. 



In meadows, Kansas and the Indian Territory. Summer. 



5. Chaetochloa purpttraacens (H.B.K. ) Scribn. & Mer. Perennial. Stems 1-6 

 dm. tall, slender, l^inching, from rootstocks : leaf-sheaths loose, striate, glabrous ; blades 

 5-10 cm. long, 4-6 mm. wide, rough on botli surfaces : racemes 1-5 cm. long, about 5 mm. 

 in diameter, the rachis pubescent : bristles 5-10, 3-8 mm. long, often barely exceeding the 

 spikelets : spikelets ovoid, acute, 2 mm. long, the flowering scale acute, transversely ru- 

 gose. 



In dry places, Texas. Also in tropical America. Spring to fall. 



6. Chaetochloa gracilis (H.B.K. ) Scribn. & Mer. Perennial. Stems erect, 3-7 

 dm. tall, slender, cylindric, simple, or somewhat branched at the base : leaf-sheaths loose, 

 glabrous ; blades involute-setaceous, 2 dm. long or less, 1-3 mm. wide : racemes dense, 2- 

 6 cm. long, 3-5 mm. in diameter : bristles 5-8, very short, equalling or twice as long as 



