HOW TO KNOW THE GRASSES 



30b. Spikelets glabrous, 4 — 7 mm. long; underground spikelets present 

 on leafless, root-like shoots. Fig. 313. 



PEANUT GRASS AmphicaTpum purshii Kunth 



Figure 313 



Annual; plants hairy, tufted, erect, 30 — 80 

 cm. tall. From the crown of the plant arise 

 slender underground runners, 2 — 5 cm. long, 

 each bearing a single large spikelet, 7 — 8 

 mm. long, at its tip. Most of the seed is 

 produced by these underground spikelets, the 

 aerial panicles being sterile. See also Fig. 

 330, which shows a subterranean spikelet. 

 Sandy or peat soil, pine barrens of the At- 

 lantic Coastal Plain. Fall. 



Amphicarpum muhlenbergianum (Schult.) 

 Hitch, is perennial, has smooth leaves and 

 stout underground rhizomes, bearing subter- 

 ranean spikelets. Pine barrens, South Caro- 

 lina to Florida. 



31a. Plants blooming twice, bearing panicles at 

 the tips of the culms in spring or early sum- 

 mer, and small axillary panicles later; win- 

 ter rosettes of short, broad leaves present in 

 most species; all perennial species. Fig. 

 314 32 



31b. Plants blooming once, all the panicles pro- 

 duced at the same period; winter rosettes 

 not present; plants annual or perennial ..41 



Summer 



Winter 



Rosette 



Figure 314 



32a. Leaf blades of the c\ilms less than 15 times longer than wide; 

 plants forming winter rosettes of short, broad leaves 33 



184 



