TRIANDRIA.— DIGYNIA. 1 9 



50. ARISTIDA, 



A. dichotoma : cespitose ; culm dichotomous ; flowers 

 racemose-spiked ; lateral awns very short ; the in- 

 termediate one contorted. 



HAB. Fields and dry hills. Sept. 0. 8— 12 in 

 high, slender; cor. l-vahed ; lat. awns straight. 



A. striata : culm and leaves straight, erect ; leaves pu- 

 bescent ; raceme long, somewhat spiked, crowded : 

 awns twice as long as the corolla, spreading. 



HAB. Sandy soils, y. . Cespitose,2 — oft. high ; /car. 

 long, convolute at the extrem. ; cor, hairy at base. 



A. purpuracens : culm filiform, erect, simple ; leaves 

 very narrow, flat ; flowers in a long spiked panicle ; 

 awns nearly equal, twice the length of the corolla, 

 divaricate. 



HAB. Sandy fields and woods. Sept. — Oct. U . 2 ft. 

 high; leav. filiform at the ext. ; panic. many-fi.> 

 purple. 



51. MUHLENBERGIA. 



M. diffusa: culm diffuse, (decumbent;) leaves linear- 

 lanceolate ; panicle branched, appressed ; awns as 

 long as the corolla. 



HAB. Dry hills and fields. Aug. — Sept. U . Culm 

 genie, slender; pan. lat. and term.; cal. scarcely 

 apparent. 



52. TRICHODIUM. 



T. laxijlorum : culm erect; leaves setaceous, ami 

 with the sheaths somewhat scabrous ; panicle dif- 

 fuse, capillary, with Irichotomous branches ; calyx 

 unequal. 

 HAB. Dry swnmps and fields. May — June. 11. Jifool 

 and a half high, filif. ; pun. at length pyramidal, 

 purplish. 

 T, scobrum: culm geniculate at the base, assurgent. 

 branched ; leaves linear-lanceolate, flat, striate, sca- 

 brou : sheaths mostly smooth ; panicle verticillate 

 and divaricate ; calyx unequal ; corolla ovate, acute. 

 '■-iH'i ved. 



Dry wgods. Aug.— Sept. )J . 12—18 in. 

 E 



