June, 1914.] The Panieums of Ohio. 347 



THE PANICUMS OF OHIO. 



Blanche McAvoy. 



This study of the Panieums of the state and the distribution 

 as given for each species are based on specimens in the state 

 herbarium at the Ohio State University. All of the Panieums 

 in the herbarium were studied and their identification revised 

 b}^ Hitchcock and Chase of the United States Department of 

 Agriculture, while the}" were preparing their material for "The 

 North American Species of Panicum." It was thought advisable 

 not to include any records of plants not so identified as it is some- 

 times difficult to discover the exact species from the older names 

 used a few }'ears ago. 



Panicum L. 



Perennial or annual grasses; inflorescence usually a panicle, 

 rarely a raceme; spikelet two-flowered, but the upper flower either 

 staminate, sterile or reduced; the empty glumes unequal, the outer- 

 most one often minute; lemma and palet of the perfect flower 

 indurated; margin of the lemma inrolled; grain freely inclosed 

 within the flowering glumes. 



Key. 

 1. Basal leaves like those of the stem. 2. 



1. Basal leaves unlike those of the stem. 10. 



2. Basal leaf-sheaths compressed, often keeled. 3. (Agrostia). 



2. Basal leaf-sheaths roimd, little flattened, never keeled. 4. 



3. Fnht stipitate. Panicum stipitatunt. (2). 



3. Fruit not stipitate. - Panicum agrostoides. (1). 



4. Leaf-sheaths smooth, panicle smooth; tall perennials having long root- 



stocks or stolons with numerous, small, broad, scale-leaves. 



Panicum virgatum. (3). 



4. Leaf-sheaths pubescent, or if smooth, then the branches of the 



panicle pubescent; annuals. 5. 



5. Leaf-sheaths smooth, panicle branches rough pubescent. 



Panicum dichotomiflorum. (4). 



5. Leaf-sheaths pubescent. 6. 



6. Spikelets ovate, more than 3^ inch long, spikelets close. 



Panicum miliacium. 



6. Spikelets lanceolate or ellii)tic, less than 3^ inch long; spikelets 



distant. 7. 



7. Panicle narrow, branches of the panicle ascending; spikelet less than 



3^ inch long. Panicum flexile. (8). 



7. Panicle spreading when mature; spikelet xe infh or l<?ss long. 8. 



8. Panicle very large, usually 3^ the plant. Panicum capullare. (6.) 



8. Panicle not so large, usually \ of the plant. 9. 



9. Stem delicate; leaf blade less than 3^4 inch wide. 



Panicum philadelphicuni. 9. 

 9. Stem stout; leaf-blade usually 3^ to % inch wide. 



Panicum gattingeri. (7). 

 10. Leaf-blades 3^ way up the stem less than 3^ inch wide, attenuate to 



cordate at the base. IL 

 10. Leaf-blades 3^ way up the stem 3^ inch or more wide, usually cor- 

 date to clasping at the base. 30. 



