GRAMINEAE 383 



DICHOTOMOUS PANICUM. 



Perennial. Culm I to 2 feet high; nodes often villous, sometimes smooth. 

 Leaves 1 or 2 inches long, the short ones numerous on the fascicled branches, 

 hairy, or smooth; sheaths often hairy; ligule bearded. Panicles terminal and 

 lateral, the former on long peduncles, the latter few-flowered, simple, on short 

 peduncles; spikelets small. 

 Hob. Dry woods ; clearings, &c. : common. FL June. Fr. Sept. 



Obs. This assumes many forms ; and I have had occasion fully 

 to verify Prof. A. GRAY'S remark, that P. dichotomum is the 

 autumnal state of several slender varieties of Panicum, observable in 

 the earlier part of the season, and which have heretofore ranked 

 as species. 



13. P. depauperatum, Muhl. Culms simple, cespitose; 

 upper leaves elongated ; panicle terminal, simple, few-flowered, 

 the branches erect and flexuose. 



P. rectum. R. $ S. $ FL Cestr. ed. 2. p. 45. 

 IMPOVERISHED PANICUM, 



Perennial. Culms 6 to 15 inches high, roughish ; nodes hairy. Leaves 3 to 6 

 inches long, erect, involute at apex, more or less pilose, the upper one overtop- 

 ping the panicle ; sheaths pubescent with long hairs. Panicle-branches somewhat 

 in pairs, one of then longer and bearing 2 spikelets ; spikelets rather large, 

 smooth, all pedunculate. 



Hob. Dry hills; Serpentine ridge: abundant. FL May. Fr. July. 

 2 3. ECHINOCHIXH : Spikelets imbricate-spiked on paniculate branches ; sterile floret 



neutral, (sometimes staminate), with 2 paleae, the lower one awned, or TOM- 



cronate. 



14. P. Crus-gdlli, L. Culms stout, smooth; spikes alternate, 

 secund; glumes, and lower palea of the neutral floret, hispid; 

 rachis hirsute. 



COCK'S-FOOT PANICUM. 



Annual. Culm 2 to 5 feet high. Leaves 9 to 15 inches long, broadish, serrulate on 

 the margins; sheaths rather loose, compressed, smooth; ligule none. Panicle 

 pyramidal, with the spikelets crowded in dense spike-form, compound racemes ; 

 spikelets ovoid, plano-convex, echinate, awned, or sometimes awnless. 

 Sab. Moist places ; Barnyard drains. Nat. of Europe. Fl. Aug. Fr. Sept. 



Obs. This coarse, weed-like grass, is usually stated to be indi- 

 genous in all the four quarters of the globe ; but I believe it to be a 

 naturalized foreigner, in Chester County. 



5O4. SETA'RIA, Beauvois. 



[Latin, Seta, a bristle; from the involucre-like bristles of the spikelets.] 

 Spikelets as in Panicum proper, awnless, but with short peduncles 

 (abortive spikelets?) produced beyond them into solitary, or clus- 

 tered bristles, resembling awns. Inflorescence a dense spiked panicle, 

 or sometimes apparently a cylindrical spike. Annuals : introduced 

 from Europe, and are all naturalized weeds, except the last, which is 

 occasionally cultivated. 



f Bristles single, or in pairs, retrorsely scabrous. 



1 S. vertidllata, Beauv. Spike pale green, nearly cylindrical, some- 

 what interrupted ; spikelets subverticillate; bristles in pairs, rather 

 short, adhesive. 



