GRASSES OF OHIO 277 



on the back with scarious margins or apex, 5-9-nerved; palets with 

 the 2 keels near the margin; stamens 2 or 3; stigmas plumose; 

 grain smooth. 



1. Spikelets linear or compressed cylindric, Vi in. long or more. :i 



1. Spikelets ovate or oblong, x /i in. long or less. \\ 



2. Lemma acute, much shorter than the palet, about x /z in. long. P. acutiflora. 



2. Lemma obtuse, nearly as long as the palet, about J4 in - long. P. septentriotialis. 



3. Lemma very broad, obscurely nerved; panicle open; spikelets 5-12-flowered. 



P. canadensis. 



3. Lemma rather narrow, sharply and distinctly 7-nerved. 4 



4. Panicle contracted, elongated and narrow; spikelets 3-4-flowered. P. torreyana. 



4. Panicle open and lax, not elongated, its branches usually spreading or droop- 

 ing. 5 



5. Empty glumes obtuse or rounded at the apex. 6 



5. Empty glumes truncate and denticulate at the apex ; inner empty glumes nearly 

 % in. long; panicle rather narrow, with few spikelets, usually less than 6 

 in. long. P. pallida. 



6. Spikelet % in. long or less; branches of the panicle often drooping; inner 

 empty glume about tV in. long. P. nervata. 



6. Spikelet nearly *4 in. long; branches of the panicle ascending or spreading; 

 inner empty glume nearly ]/§ in. long. P. grandis. 



1. Panicularia acutiflora (Torr.) Ktz. Sharp-glumed Manna- 

 grass. A grass 1-2 ft. high, with flattened weak and slender stems, 

 and with overlapping sheaths, the uppermost inclosing the base of 

 the slender panicle. Spikelets linear, 5-12-flowered, erect on the 

 panicle, lemma acute, scabrous, much exceeded by the long-acuminate 

 palet. 



In wet soil and shallow water. June-August. No specimens. 



2. Panicularia septentrionalis (Hjitch.) Bickn. Floating Manna- 

 grass. An erect grass with somewhat flattened stems, 2-3 ft. high, 

 from a creeping base and with a very slender panicle of a few re- 

 mote branches which are at first appressed or finally horizontal. 

 Spikelets 7-12-flowered, compressed-cylindric, subsessile ; lemma 

 hispidulous, 7-nerved, obtuse, somewhat exceeded by the acuminate 

 palet. 



In shallow water. June, July. General as far south as Har- 

 rison, Perry, Franklin and Auglaize Counties. 



3. Panicularia canadensis (Mx.) Ktz. Rattlesnake Manna- 

 grass. A grass with erect simple stems, 2-3 ft. high, with com- 

 pressed sheaths, and with very loose open panicles, the remote ca- 

 pillary branches drooping. Spikelets 5-12-flowered, ovate, tumid; 

 lemma broad, obtuse or abruptly acute, obscurely 7-nerved. 



In swamps and wet places. July, August. Ashtabula, Geauga, 

 Portage, Cuyahoga, Lorain, Summit, Stark, Wayne. 



4. Panicularia torreyana (Spreng.) Merr. Long Manna-grass. 

 A grass with solitary or few erect stems, 1-3 ft. high, from a run- 



