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MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



to 3 cm. long, tapering into an awn. 

 the first 3- to 5-nerved; lemma about 

 2 cm. long, the awns about equal, 

 divergent, 4 to 7 cm. long, somewhat 

 spirally curved at base. O — Open 

 dry ground, Massachusetts to South 

 Dakota, south to Florida and Texas: 

 Oregon to Arizona, 



12. Aristida ramosissima Engelm. 

 ex A. Gray. (Fig. 683.) Annual, much 

 branched; culms 30 to 50 cm. tall; 

 blades flat or involute, about 1 mm. 

 wide; panicle narrow, 8 to 12 cm. 

 long; glumes 3- to 5-nerved, the first 

 about 15 mm., the second about 2 

 cm. long, including an awn 3 to 5 

 mm. long; lemma about 2 cm. long, 

 tapering into a neck about 5 mm. 

 long; central awn with a semicircular 

 bend or part of a coil at base, 15 to 

 20 mm. long, spreading, the lateral 

 awns reduced or as much as 6 mm. 

 long, rarely longer. O — Open 

 sterile soil. Indiana to Iowa, south 

 to Tennessee, Louisiana, Oklahoma, 

 and Texas. 



13. Aristida longespica Poir. (Fig. 

 684.) Annual, branched; culms 20 to 

 40 cm. tall; blades flat or involute, 

 about 1 mm. wide; panicles narrow, 

 slender, the terminal 10 to 15 cm. or 

 even 20 cm. long; glumes about equal, 

 5 mm. long; lemma 4 to 5 mm. long; 

 central awn sharply curved at base, 

 spreading, 5 to 15 mm. long, the 

 lateral awns erect, one-third to half 

 as long as the central, sometimes 

 only 1 mm. long. O (.4. gracilis 

 Ell.) — Sterile or sandy soil. Xew 

 Hampshire to Michigan and Kansas, 

 south to Florida and Texas, especially 

 on the Coastal Plain. In the typical 

 form the lateral awns are short; in 

 var. geniculate. Fernald (.4. genicu- 

 lata Raf.) the lateral awns are more 

 than one-third as long as the central 

 one. 



14. Aristida adscensionis L. Six- 

 weeks three-awx. (Fig. 685.) An- 

 nual, branched at base, erect or 

 spreading; culms 10 to 80 cm. tall; 

 panicle narrow and usually rather 

 compact. 5 to 10 cm. long, or longer 

 in large plants; first glume 5 to 7 



Figure 681. — Aristida curtissii, X 1. CW aite, 111.) 



conspicuous blades, the looser pan- 

 icles of larger spikelets. the more un- 

 equal glumes, the longer second 

 glume (about 1 cm. long), the longer 

 smooth lemma (about 1 cm. long) and 

 central awn, and the usually longer 

 lateral awns; central awn about 1 

 cm. long, the lateral awns 2 to 4 mm. 

 long. O — Open dry ground, 

 Maryland and Virginia to South Da- 

 kota, Wyoming. Colorado, and Ken- 

 tucky to Oklahoma; Florida. 



11. Aristida oligantha Michx. 

 Prairie three-awx. (Fig. 682.) An- 

 nual, much branched; culms 30 to 50 

 cm. tall; blades flat or loosely invo- 

 lute, usually not more than 1 mm. 

 wide: panicle loose. 10 to 20 cm. long: 

 spikelets short-pediceled, the lower 

 often in pairs: o-Jume< about equal. 2 



