HITCHCOCK AND CHASE—TROPICAL NORTH AMERICAN PANICUM. 461 
Blades linear, many times as long as broad; spikelets 1.7 mm. 
or more long. 
First glume not over one-fourth the length of the spikelet, 
truncate or triangular-tipped. 
See DicHoromirtora, p. 473. 
First glume usually as much as half the length of the spike- 
let, acute or acuminate....... See CAPILLARIA, p. 476. 
Plants perennial. 
Spikelets short-pediceled along one side of the panicle branches, forming 
more or less spikelike racemes. 
First glume nearly as long as the obtuse spikelets; plants with long wiry 
stolons: with woolly nodes... . 2202025. 0000 04 111. P. obtusum. 
First glume much shorter than the spikelet. 
Spikelets more or less hispid. 
Sterile lemma glandless; second glume inflated-gibbous. 
73. P. ineptum. 
Sterile lemma bearing a pair of crateriform glands. 
See STOLONIFERA, p. 500. 
Spikelets glabrous. 
Blades lanceolate or ovate-lanceolate; glumes strongly carinate. 
See STOLONIFERA, p. 500. 
Blades linear, often elongated; glumes not carinate or but slightly so. 
Fruit transversely rugose.........------- See GreMINATA, p. 465. 
Fruit not rugose. 
Second glume shorter than the spikelet; fertile lemma subin- 
durate, inrolled only at base, scabrous at the acute apex. 
112. P. stagnatile. 
Second glume as long as the spikelet; fertile lemma indurate, 
imtolled:to the summit. 4.2.26 2t 2. se ok See Laxa, p. 492. 
Spikelets in open or sometimes in contracted or congested Horitieles but 
not in 1-sided spikelike racemes. 
Brit iratisVersely TUSOSC. eo ot ee eee es See Maxma, p. 483. 
Fruit not transversely rugose (minutely papillose-roughened in P. 
millegrana). 
Culms more or less succulent; plants glabrous or nearly so throughout, 
aquatic or subaquatic. 
First glume not over one-fifth the length of the spikelet. 
See DicHoTOMIFLORA, p. 473. 
First glume one-third to half the length of the spikelet. 
Fruit indurate, the margins of the lemma inrolled; culms erect; 
Pramicle COM TrACted ee os ea 48. P. condensum. 
Fruit subindurate, the margins of the lemma inrolled only at 
base; culms decumbent at base; panicles open. 
Spikelets 1.8 mm. long; second glume shorter than the fruit; 
: secondary panicle branches secund..... 112. P. stagnatile. 
Spikelets 2.5 mm. long; second glume exceeding the fruit; 
panicle branches not secund........ sbtearas 113. P. grande. 
Culms not succulent. 
First glume hyaline, inconspicuous; spikelets acuminate; lower 
blades with long petiole-like bases........ 114. P. tuerckheimin. 
First glume evident. 
First glume very small, not over one-fourth the length of the 
small obovate, blunt, glabrous spikelets. 
See PaRvicLumIA, p. 502. 
