162 PANIC ACE^. 



the preceding, spikelets much smaller, fertile floret 3 mm. long. 

 This corresponds with the remark of Grisebach in his Flora of the 

 West Indies, ''All West Indian specimens agree in the small size 

 of the spikelet, while in the northern, original form, the spikelets 

 are usually twice as large; the species, however, is as variable as the 

 preceding (C. ecliinatus L.) and often difficult to be distinguished 

 from it." 



A plant from Mobile, Ala., sent by Dr. C. Mohr, is no doubt 

 C. incertus Curtiss. The second glume is 5-nerved, third glume 

 or palea of the lower floret contains a staminate flower. Most likely 

 G. incertus Curtiss, also C. jjmiciflorus Benth., should be included 

 in the above variable species. 



A troublesome weed on sandy lands found from Xew England 

 to California, West Indies, Mexico, Brazil, Africa, East Indies. 



5. C. Palmeri Vasey, Proc. Cal. Acad. (11.) 2: 211 (1889). 



Annual; culms rather slender, geniculate, branching, about 30 

 cm. high. Sheaths loose, about as long as the internodes; ligule 

 hairy; blades numerous, rough, flat, 10. cm. long, 5-8 mm. wide. 

 Peduncles exserted, bearing 2-3 twinlike downy burs 2 cm. long, 

 including the stout spines before they are bent and hardened, 

 each bur including 5-7 spikelets. Spikelets ovoid, acute, 6 

 mm. or more long; first and second glumes alike, ovate-cuneate, 

 obtuse, truncate or irregularly divided with 5 strong green nerves; 

 palea of the staminate flower about the length and shape of the 

 empty glumes, 2-nerved; floral glume of the fertile floret oval, 

 as long as the emjoty glumes, acuminate with 7 prominent nerves, 

 its palea with 2 strong nerves. When mature the burs are often 

 3 cm. diam. from the tips of the stout spines. Spines yellow or 

 black. 



Lower California, Palmer 689; Mexico, Palmer 271. 



Abundant on sandy bottoms, where it must be a formidable 

 nuisance to man and beast. 



32. (14). Pennisetum Piich. Pers. Syn. 1:72(1805). Peni- 

 cillaria Wild. Enum. Hort. Berol. 1036 (1809). Gijmnothrix 

 Beauv. Agrost. 59, t. 13, f. 6 (1812). Catatherophora Steud. 

 Flora, 12:465 (1829). Pentastachya Hochst. Steud. Norn. Ed. 2, 



