GEAMINEAE 15 



1. T. dactyloides L. Gama Grass. 4°-8° high, bearirg 1-3 spikes 

 at the summit, as well as some from the upper axils : leaves broad and 

 flat. — Common throughout in wet places, especially in prairie swales. 

 June-July. 



2. ANDROFOGON L. Bboom-gbass. 



Perennials, bearing spikelets in pairs at each joint of the raohis, one of 

 them perfect and sessile with four glumes, the lower thick, the second 

 acute and carluate, the upper two thin. Flowering glume more or less 

 awned. The other spikelet pedicelled and sterile. 



Spikes not in pairs or clustered. 1. A. scoparius. 

 Si>ikes in pairs or digitate. 



Hairs on rachis internodes 1" long. 2. A. furcatus. 



Hairs on rachis internodea lJ''-2''' long. 3. A. chryaocom.ua. 



Spikes densely clustered. 4. A. Torreyanua. 



1. A. scopaiius Michx. l°-4° high : spikes peduncled, numerous, 

 hairy with long dull white hairs : sterile spikelet an awn-pointed scale : 

 awn of fertile spikelet about S^-B" long. — Common in open rocky woods 

 and prairies, especially in the southern part. July-September. 



2. A. furcatus Mnhl. Tall, 3°-6° high : spikes 2-5, approximate at 

 the summit : hairs on the rachis and pedicels short : sterile spikelet stam- 

 inate, with four scales : awn of fertile spikelet h"-1" long, bent. — Com- 

 mon in similar situations, and usually with the last. July-September. 



3. A. chrysocomus Nash. Closely resembles the last, but outer scales 

 of sessile spikelets smooth except on nerves (hispidulous in A. fureaiua), 

 and rachis hairs longer and usually yellow. — In similar situations as the 

 last. August-October. 



4. A. Torreyanus Steud. 2°-4° high : spikes numerous, in a terminal, 

 spicate panicle : hairs of spikelet long, white : sterile spikelet scale-like : 

 awn of fertile spikelet i"-&' long, bent. — Well adventized in one locality 

 at Sheffield ; also near Red Bridge. June-September. 



3. SORGHASTRUM Nash. 



Tall perennials with spikelets in pairs or threes in an open panicle, the 

 middle one sessile and perfect with four scales, the outer thick and shin- 

 ing. Lateral flowers pedicelled, reduced to plumose pedicels. 



1. S. avenaoeum (Michx.) Nash. Indian Grass. 3°-6° high: 

 panicle branches erect spreading : spikelets yellowish or brownish, hairy : 

 awn twisted, b"-W' long, the column not bent. — In dry open soil, 

 throughout. Probably includes two species with us. August-September. 



4. SORGHUM Pers. 



Spikelets two together, one sessile and fertile, the other pedicelled, 

 sterile. Perfect spikelet with four scales, the fourth awned. 



