116 PANIC ACE ^. 



Culms slender, usually creeping at the base, 30-60 cm. high. 

 Sheaths shorter than the internodes; blades 2-8 cm. long, 5-15 

 mm. wide, lanceolate, flat, glabrous, except cilia on the margins 

 near the broad base, at the throat and sometimes on the sheath. 

 Panicle exserted, of 3-10 simple, crowded, spikes, 1-4 cm. long. 

 Spikelets single or 2-3 together in alternate rows on two sides of a 

 flexuose, rougli. triangular rachis. pedicels unequal, very short, 

 often bearing bristles, smooth, flattened, oval, almost acute, con- 

 taining a staminate and a perfect flower, first empty glume mem- 

 branous, very short, broad, second broad-oval, 5-7-nerved; floral 

 glume of t]ie lower floret ovate, 5-nerved; palea as long. Stamens 

 3. Upper floret oval, finely rugose, mucronate or obtuse, 1.5 mm. 

 long. 



Louisiana, A. B. Langlois. 



Found in the southern U. S., West Indies, Brazil, Egypt, 

 Arabia, East Indies, Australia. 



18. P. GEOSSARiUM L. AmoBu. Acad. 5: 392 (1759). P. cces- 

 piiosum Sjireng. ex Steud. Xom. Ed. 2, 2:253 (1841). 



Culms smooth, rather slender. 10-30 cm. high, branching from 

 a decumbent or creeping base, the lower internodes about 3 mm. 

 long. Margins of the sheaths and ligule hairy; blades flat, ovate- 

 lanceolate, acute, 2-5 cm. long, 5-10 mm. wide, tlie margins near 

 the base pubescent. Panicle much or little exserted above the short 

 sheath or the lower partially included, consisting of about 6 ap- 

 proximate spikes, eacli 2-3 cm. long. Spikelets mostly in pairs on 

 two sides of a slender, flexuose, triangular rachis, 1 subsessile, 1 

 borne on a pedicel 1-2 cm. long, elliptical-obovate, mucronate, 3 

 mm. long, first glume broad, about one-third of the length of the 

 spikelet, 5-7-nerved, second glume ovate, acute, 8-9-nerved; floral 

 ghime of the neuter spikelet a little shorter, 5-nerved, its palea 

 shorter and much narrower; fertile floret firm^ elliptical, trans- 

 versely wrinkled, 2.5 mm. long. 



P. adspersKin Trin. Gram. Panic, as figured, appears to be the 

 same as the above, only the leaves are longer and wider, the spikelets 

 2-3 in number and longer. 



Introduced into Philadelphia, Penn., on ballast-ground. 



