246 MISC. PUBLICATION 243, U.S. DEPT. OF AGRICULTURE 
Culms erect. 
Panicles strongly contracted, elongate; seacoast 
plants growing in large bunches. 
24. P. AMARULUM. 
Panicles open, rather narrow; plants of low ground 
but not littoral, the culms solitary or few in a 
clumpae es aes 22. P.VIRGATUM var. CUBENSE. 
7b. Plants not forming creeping scaly rhizomes. 
Fruit crested at apex; spikelets 5.5 to 6 mm long. 
06. P. ZIZANIOIDES. 
Fruit not crested. 
Panicles narrow and few-flowered; culms erect and wiry; 
blades drying involute. 
Second glume and sterile lemma exceeding the fruit; 
spikelets somewhat pointed. 
Pedicels bearing a few long hairs_26. P. TENERUM. 
Pedicels puberulent, without long hairs. 
30. P. BEYERI. 
Second glume and sterile lemma not exceeding the 
fruit; spikelets rather blunt. 
Pedicels bearing a few long stiff erect hairs at the 
SUT rn Oh Byes yah age Be se 27. P. CARICOIDES. 
Pedicels not hairy. 
Spikelets attenuate at base, about 2 mm long; 
leaves more or less pilose. 
28. P. STENODOIDES. 
Spikelets not attenuate at base, about 1.5 mm 
long; leaves glabrous____29. P. STENODEs. 
Panicles open or contracted. 
Panicles 40 to 60 cm long, the numerous elongate 
branches in ‘verticils:_=_-=-__ 52. P. MERTENSII. 
Panicles mostly much less than 40 cm long; branches 
not verticillate. 
First glume not pointed, two-thirds the length of 
the spikelet or more; spikelets blunt. 
Panicles not more than 6 cm long; plants some- 
what glaucous, relatively small; blades 
mostly less than 8 em long. 
Culms very slender, decumbent or creeping; 
blades 1 to 3cm long_45. P. PARVIFOLIUM. 
Culms firm, erect or decumbent at base only; 
blades 3 to 8cm long_46. P. CYANESCENS. 
Panicles 10 to 20 em long, diffuse; plants tall or 
stout. 
Blades gradually narrowed from a clasping 
base, stiff, striate, erect or ascending. 
P. NERVOSUM. 
Blades not clasping at base. 
Spikelets viscid, 3 mm long. 
50. P. GLUTINOSUM. 
Spikelets not viscid, 2 to 2.3 mm long. 
49. P. SELLOWIL. 
First glume pointed, usually less than two-thirds as 
long as the spikelets. 
Spikelets sparsely hirsute_____- 51. P. RUDGET. 
Spikelets glabrous. 
Culms straggling; spikelets minute. 
P. TRICHANTHUM. 
Culms erect or stiffly ascending. 
Culms tall and stout, usually more than 
1 m tall. 
Sheaths hirsute: ______ 18. P. HIRSUTUM. 
Sheaths glabrous___-_- 25. P. PETERSONII. 
Culms slender, less than 1 m tall. 
Blades 1 to 3 mm wide; plants spreading 
Gr ascending== = 16. P. DIFFUSUM. 
Blades mostly more than 5 mm wide; 
plants erect.__17. P. GHIESBREGHTII. 
