GRAMINEAE. 69 



single scale. Perfect spikelet consisting of 4 scales, the outer 2 coriaceous, the 

 second keeled and acute, the two inner hyaline, the fourth more or less awned and 

 subtending a palet and perfect flower. Stamens 1-3. Grain free. [Greek, in 

 allusion to the bearded rachis.] About 150 species, widely distributed in tropical 

 and temperate regions. Besides the following, some 25 others occur in the south- 

 ern and western parts of N. Am. 



Racemes singly disposed ; apex of the rachilla internodes with a translucent cup-shaped 

 entire or irregularly-toothed appendage. 

 Spikelets 5-7 mm. long; sheaths of the innovations green. 1. A. scoparius. 



Spikelets 8-1O mm. long; sheets of the innovations strongly compressed, glaucous. 



2. A. littoralis. 

 Racemes disposed in pairs or more ; apex of the rachis internodes unappendaged. 

 Pedicellate spikelet sterile, of 1 or 2 scales, much smaller than the sessile one. 



Racemes usually protruding from the lateral fissure of the spathe, sometimes 

 more or less exserted from the apex, the peduncle never long-exserted. 

 Branches of the inflorescence crowded at the summit of the culm in a dense 



corymbiform panicle. 3. A. corymbosus. 



Branches of the inflorescence scattered along the culm in a long linear 

 panicle. 4. A. Virginicus. 



Racemes much exserted on long peduncles. 



Stamen 1 ; upper sheaths much enlarged. 5. A. Elliottii. 



Stamens 3; sheaths not enlarged. 



First scale of the spikelet nerveless between the keels ; terminal hairs of 



the internodes about twice their length. 6. A. argyraeus. 



First scale of the spikelet with 2 or 3 nerves between the keels ; terminal 

 hairs of the internodes about equalling them. 



7. A. Cabanisii. 

 Pedicellate spikelet as large as or larger than the sessile, of 4 scales and a stamin.Ue 



or rarely perfect flower. 

 Fourth scale of sessile spikelet with a long geniculate awn, more or less spiral 

 at the base. 

 Outer two scales of the sessile spikelet more or less hispidulous all over ; 

 hairs on the rachis internodes usually 2 mm. or less long. 



8. A.farcatus. 

 Outer 2 scales of the sessile spikelet smooth or nearly so, except on the 



nerves ; hairs of the rachis internodes 3-4 mm. long, usually yellow. 



9. A. chrysocomus. 

 Fourth scale of the sessile spikelet awnless or with a short, straight, untwisted 



awn. 



Marginal hairs on the pedicels and rachis internodes copious, stiff. 



10. A. Hallii. 



Marginal hairs on the pedicels and rachis internodes scant or almost want- 

 ing, lax, crisped. n. A. paacipilus. 



1. Andropogon scoparius Michx. Broom Beard-grass. (I. F. f. 216.) 

 Culms tufted, 6-12 dm. tall. Sheaths sometimes glaucous ; leaves 1.5-3 dm. long, 

 scabrous ; spikes 2.5-5 cm - l° n g' loose, solitary, on long-exserted slender peduncles ; 

 rachis slender, flexuous, joints and pedicels ciliate with long, spreading hairs ; outer- 

 most scale of sessile spikelet about 6 mm. long; awn spiral. 10-12 mm. long ; pedi- 

 celled spikelet a single awn-pointed scale. In dry sandy fields, N. B. to Alb. south 

 to Fla. and Tex. Aug.-OcL 



2. Andropogon littoralis Nash. Seaside Beard-grass. Culms densely 

 tufted, 8-10 dm. tall, the innovations with the leaves and strongly compressed 

 sheaths glaucous; leaves 2 dm. long or less, rough; racemes 3-4 cm. long, 

 rarely longer; sessile spikelets 8-10 mm. long, the awn of the fourth scale 

 geniculate, spiral, 10-15 mm - lon g ; pedicellate spikelet a single-awned scale. In 

 sand along the seashore, N. Y. and N. J. Aug.-Oct 



3. Andropogon corymbosus (Chapm.) Nash. Bushy Beard-grass. (I. F. 

 f. 221.) Culms 4-10 dm. tall, from a little exceeding to twice as long as the basal 

 leaves; sheaths keeled, those at the base much compressed and equitant, rough, 

 more or less papillose-hirsute; culm leaves rough; spathes very rough, tightly en- 

 rolled around the common peduncle, which is usually as long as the spathe and 

 hispidulous toward the summit; racemes in pairs, more or less exserted, 2-3 cm. 



