ORDER CXLII. GRAMINACE^E. 583 



5. A. spicifor'mis, (Ell.) Ste?n' erect, simple, compressed. Leaves 

 linear ; sheaths glabrous. Flowers in compound racemes, appressed. 

 Glumes shorter than the paleae, terminated by awns. Palcee unequal, 

 exterior one 3-awned, with the intermediate one longest, pubescent at 

 the base. — 2f . Sept. — Oct. Pine-barrens. 1 — 3 feet. 



Tribe V.— AGROSTI'DE^E. 



Spikelets 1 -flowered. 



Genus XVII.— MUHLENBER'GIA. Schreb. 

 (In honor of Dr. Muhlenberg.) 



Glumes 2, very minute, fringed. Palece ovate, gibbous, much 

 larger than the glumes, the lower one awned. Panicle simple. 



1. M. diffu'sa, (Willd.) Stem decumbent, geniculate, diffuse, com- 

 pressed. Leaves linear, scabrous. Panicle slender, composed of alter- 

 nate, appressed racemes. Glumes unequal, small. Palece unequal, 

 pubescent at the base, the exterior 3-nerved; awn purple. — 2f. July. 

 In fields. 18—20 inches. 



2. M. polypo'gon, (Trim) Leaves convolute, glaucous. Pedicels crowd- 

 ed ; awn longer than the floret ; glumes awned at the apex. — Carolina. 



3. M. cafilla'ris, (Trim) Leaves convolute, long, glaucous. Flowers 

 crowded ; paleae 3 times as long as the glumes ; awns naked. 



4. M. erec'ta, (Pursh.) Stem erect, simple, pubescent. Leaves pu- 

 bescent ; sheath shorter than the joint, hairy at the throat. Panicle 

 loose. Glumes 2, with one very minute. Palem with the exterior one 

 bearing a long awn, many-nerved. — 2f . July. Rocky hills. 2 — 3 ft. 



Genus XVIII.— AGROS'TIS. L. 



(From agros, a field; the place of growth.) 



Glume naked, beardless, 2-valved, 1-rlowered ; valves longer 

 than the paleae. Palece 2, membranaceous. Stigmas longitu- 

 dinally hispid. 



1. A. dis'far, (Mich.) Erect, large. Panicle loose, many-flowered, 

 somewhat verticillate and pyramidal ; the exterior glume the largest, 

 one of the interior very small. — Low country. 



2. A. laxiflo'ra, (Rich.) {Trichodium laxijlorum, Mich.) Stem erect, 

 glabrous. Leaves setaceous, scabrous. Panicles diffuse, capillary, with 

 trichotomous branches. Glumes unequal, lanceolate, acute. Palea 

 shorter than the glumes, with the margins pubescent. — If. March — 

 May. Dry fields or swamps. 18 inches to 3 feet. 



3. A. triciiopo'des, (Ell.) Stem erect, glabrous. Leaves flat, sca- 

 brous ; sheath glabrous, with long stipules. Panicle diffuse. Pedun 

 cles capillary, long. Glumes much shorter than the paleae ; the exterior 

 palea with a short, straight awn, the interior longest. — If. Sept.— 

 Oct. Common. 2 — 3 feet. 



4. A. araciinoi'des, (Ell.) ( Cinna arachnoidea, Kuuth.) Stem erect, 

 elender, glabrous. Leaves with the sheath as long as the joints. Stip- 



