(GRASS FAMILY.) 573 



narrow and simple panicle ; rachis flexuous, naked and bristle-like at the apex ; 

 spikelets ovate (l"long); upper glume 9-nerved, twice as long as the obtuse 

 lower one. South Florida. Culms l-2 high. Racemes distant on the 

 common rachis, ' long. 



*- - Sterile flower oftwopalece, staminate or neutral. 



4. P. gibbum, Ell. Panicle spiked, cylindrical, , 3' - 5' long ; spikelets 

 oblong, obtuse; upper glume oval, strongly 11-nerved, tumid at the base, 

 twice as long as the smooth fertile flower, the lower one minute ; sterile flower 

 3-androus ; culms branched, slender, reclining ; leaves linear-lanceolate, smooth 

 or hairy. Swamps, Florida to North Carolina. July - Sept. Plant deep 

 green. Spikelets caducous. 



5. P. Curtisii. Panicle slender, spike-like (6' -8' long), the appressed 

 lower branches remote ; spikelets ovate-lanceolate ; glumes slightly keeled, the 

 upper 5-nerved, twice as long as the lower one, and rather shorter than the 

 acutish flower ; sterile flower 3-androus ; culms and smooth linear-lanceolate 

 leaves rigid ; sheaths smooth or hairy. (P. Walteri, Ell, not of Poiret nor 

 Pursh. P. carinatum, Torr., in Curtis's Plants, Wilmington, not of Presl.) 

 Ponds and swamps, Florida to North Carolina. Culms 3 - 4 high, often 

 rooting at the lower joints. 



6. P. hians, Ell. Panicle small, the few scattered and spreading branches 

 naked below ; spikelets in small distinct clusters, ovate ; upper glume 5-nerved, 

 3-4 times longer than the lower ; sterile flowers neutral, longer than the perfect 

 flower, the upper palea rigid, obovate, involute, gaping at the apex; culms 

 slender (6' -18' high), simple; leaves linear, smooth. Low grounds in fields 

 and along roads, Florida to North Carolina. 



7. P. gymnocarpum, Ell. Panicle large, pyramidal, the rigid expand- 

 ing branches mostly clustered or whorled ; spikelets 3 - 6 in scattered clusters 

 (2" long), lanceolate; glumes lanceolate-subulate, rough-keeled, 2-3 times 

 longer than the perfect flower ; sterile flower neutral ; the lower palea as long 

 as the lower glume, and much longer than the upper palea ; culms rigid, erect ; 

 leaves (!' or more wide) lanceolate, cordate, smooth. Muddy banks of rivers, 

 Florida, Georgia, and westward. Sept. 1J. Culms 2 - 3 high. Sheaths 

 imbricated. 



8. P. anceps, L. Panicles lateral and terminal, diffuse ; spikelets 3-10 

 in mostly scattered clusters, ovate-lanceolate, acute ; glumes smooth, keeled, 

 compressed at the apex, the upper 7-nerved, twice as long as the lower one, and 

 one third longer than the fertile flower ; culms flattened. Var. STRICTUM. 

 Culms strict and rigid, like the erect leaves ; panicle filiform, of few appressed 

 branches, 2' - 3' long. Damp sterile soil, Florida, and northward. Common and 

 very variable. Aug. and Sept. 1J. Plant mostly pale. Spikelets often purple. 



* * Spikelets mostly by pairs, on short appressed pedicels (except Nos. 13 and 14), 



scattered on the ultimate branches of the usually ample open panicle. 



- Sterile flower consisting oftwopalece. 



9. P. virgatum, L. Culms tall (2 - 4 high) ; branches of the large dif- 

 fuse panicle whorled or clustered ; spikelets (1" long) on rough pedicels, ovate ; 



