HOW TO KNOW THE GRASSES 



9a. Plants usually 1 m. toll or shorter; leaf blades usually 1 cm. wide 

 or narrower; plants widespread, not in coastal marshes 10 



9b. Plants 1 — 4 m. tall; larger leaf blades 1 — 4 cm. wide; plants of 



coastal marshes along the Atlantic and Gulf of Mexico. Fig. 289. 



GIANT FOXTAIL Setaria magna Griseb. 



-i 



Figure 289 



Annual; tufted; culms stout and tall, up 

 to 2 cm. thick and 4 m. tall; leaf blades 

 flat and scabrous, up to 50 cm. long. The 

 immense panicles reach lengths of 50 cm. 

 and diameters of 3.5 cm. They are some- 

 what nodding and may be lobed at the 

 base, thickest at the middle and tapering 

 toward the ends. Axillary panicles are 

 much smaller than the terminal one. 

 Bristles 1 — 2 cm. long; spikelets about 2 

 mm. long; fertile floret smooth and shin- 

 ing, brown when ripe. Giant foxtail is a 

 characteristic plant of coastal marshes, 

 found in the interior only in Arkansas. Its 

 range also extends to the West Indies. 

 August — September. 



10a. Plants annual, with soft bases and shallow roots; leaf blades usu- 

 ally less than 15 cm. long, flat; panicles usually less than 10 cm. 

 long, with dense spreading bristles. Fig. 290. 



GREEN FOXTAIL Setaria viridis (L.) Beauv. 



Figure 290 



panicle branches. 



Annual; tufted; becoming much-branched 

 from the base, 20 — 100 cm. tall; leaf 

 sheaths glabrous except for the short cilia 

 along the margins; blades glabrous, usual- 

 ly less than 10 mm. wide; panicles soft, 

 sUghtly nodding near the tip; bristles 

 green, rarely purple; spikelets 1.9 — 2.2 mm. 

 long, greenish except when ripe; second 

 glume and sterile lemma nearly covering 

 the fertile floret; fertile lemma nearly 

 smooth. Green foxtail is one of the com- 

 monest weeds of cornfields and other areas 

 of disturbed soil. The bristles are sterile 

 July — October. Introduced from Europe. 



153 



