TRIANDRIA DIGYNIA. 313 



crowded, compound, remote, smooth ; spikelets minute, obtuse, ovate, 

 slightly pubescent ; inferior glume very small. 



HAB. Meadows and woods. June July, Tj.; culm 18 inches 2 

 feet high, mostly simple; nodes annulate leaves a little shining. 



P. agrostoides : culm compressed, smooth, erect ; leaves very long , 

 panicles lateral and terminal, pyramidal, spreading; branches ra- 

 cemiferous; spikelets appressed; abortive floret neuter, with the 

 valves nearly equal. 



HAB. Wet meadows. July September, TJ.; culm 2 3 feet high 

 leaves numerous at the root panicle dark purple. 



P. proliferum : culm assurgent, geniculate at the base, very smooth ; 

 panicles terminal and axillary; smooth; spikelets racemose; abor- 

 tive floret 1-valved. 



HAB. Wet meadows. September, 7j. ; whole plant very smooth 

 culm 2 4 feet long, succulent leaves broad panicles large an- 

 thers orange. 



P. capillare : culm nearly simple ; sheaths very hairy ; panicles large, 

 capillary, expanding, loose ; spikelets on long peduncles, acuminate, 

 smooth ; abortive floret 1-valved. 



HAB. Cultivated grounds. Aug Sept. Ij.; culm erect, 1 2 feet 

 high sheaths hispid branches of the panicles reflexuous when 

 old. 



65. SETARIA. 



S. viridis : spike cylindrical ; involucrum of 4 10 fasciculate bristles, 

 scabrous upward ; spikelets geminate ; perfect floret smooth ; sheaths 

 pubescent. 



HAB. Cultivated grounds. July August, 'ZJ.; culm 1| feet high, 

 simple leaves smooth involucrum, longer than the Jlower. 



S. glauca : spike cylindrical ; involucrum of many fascicled bristles, 

 scabrous upward ; perfect floret transversely rugose. 



HAB. Fields and cultivated grounds. July August, (v) ; culm 2 

 feet high involucrum yellow when old. 



b. purpurascens : sheaths hairy ; glumes and bristles of the involucrum 

 purple. 



S. verticillata : spike subverticillate ; bristles of the involucrum two, 

 retrorsely scabrous ; spikelets solitary ; corolla of the perfect floret 

 nearly smooth. 



HAB. Sandy cultivated grounds. July, (v) ; culm 18 inches high, 

 smooth ; spike 2 inches long ; rach. hispid involucrum purplish. 



S. italica : spike compound, interrupted at the base, nodding ; spike- 

 lets conglomerate ; involucrum many times longer than the flowers ; 

 rachis tomentose. 



HAB. Borders of ditches. July August, <v) ; culm 4 feet high, sub- 

 compressed; panicles 68 inches long; involucrum 1 2 inches 

 long. 



66. DIGITARIA. Crab-grass. 



D. sanguinalis : spikes numerous, fasciculate, a little spreading ; 

 leaves and sheaths somewhat hairy ; spikelets oblong ; florets pubes- 

 cent on the margin. 



HAB. Cultivated grounds and waste places. August, 7J.; culm 

 decumbent and assurgent ; spikes 4 6 ; rach. Jlexuous ; spiff eleta 

 by pairs. 



