Xv SYNOPSIS OF GENERA. 



CALAMAGROSTIS. Panicle loose. Cal. of 2 valvesj longer than the two 

 valves of the corolla, p. 297. 



AGROSTIS. Cal, of 2 acute valves, shorter than the cor. which is membra- 

 nous, tufted with hairs at the base, unchanged. Seed loose, p. 298. 



* * Fl. dispersed. Cal. of 2 valves, containing 2 or 3 florets. 



CATABROSA. Panicle spreading. Cal. of 2 valves, metnbranaceous, very 

 obtuse, much shorter than the spikelets, 2 or 3-flowered, often with a fourth 

 imperfect floret. Cor. 2-valved, coriaceous, membranous only at the extre- 

 mity, ribbed, truncated, awnless, erose, nearly equal, p. 299. 



AIRA. Florets 2, without any intermediate rudiment. Seed loose. Cor. 

 unchanged, p. 299. 



MELTCA. Florets 1 or 2, with the rudiments of 1 or 2 intermediate ones. 

 Seed coated with the hardened cor. p. 300. 



HOLCUS. One floret barren. Cor. awned. Seed coated with the hardened 

 corolla. Cal. keeled, p. 30 ]. 



ARRHENATHERUM. Panicle lax. Cal. of 2 valves, 2-flowered; lower- 

 most floret with stamens only, and a long twisted awn above the base, upper 

 one perfect, with a short straight bristle below the point, p. 302. 



SESLERIA. Florets 2 or 3, all perfect. Outer valve of the cor. toothed; 

 inner cloven. Seed loose. Styles combined, p. 302. 



* * * Fl. dispersed. Cal. containing many florets. 



POA. Cor. awnless, compressed, keeled, ovate, acute. Seed loose, elliptic- 

 oblong, p. 302. 



TRIODIA. Cor. orbicular, expanded, obscurely ribbed, deeply cloven, with 

 an intermediate point ; both valves concave. Seed loose, depressed, p. 306. 



BRIZA. Cor. awnless, tumid, expanded, concave, without a keel. Seed 

 depressed, united to the corolla, p. 306. 



DACTYLIS. Cor. awned at the summit, lanceolate, keeled, compressed; 

 inner valve folded, 2 ribbed. Seed loose, oblong. Cal. compressed, taper- 

 pointed, unequal, p. 307. 



CYNOSURTJS. Cor. awned at the summit, lanceolate, keeled, concave; 

 inner valve flat, 2-ribbed. Seed loose, elliptic-oblong. Cal. awned, equal. 

 Spikelets in pairs ; 1 entirely neuter, p. 307- 



FESTTJCA. Cor. awned at the summit, or pointed, keeled, nearly cylin- 

 drical, concave; inner valve flat, 2 ribbed, downy at the ribs. Seed loose, 

 oblong. Cal. concave, acute, very unequal, p. 3U7- 



BROMUS. Cor. awned at the back, cloven, concave; inner valve flat, 

 2-ribbed, bristly at the ribs. Seed elliptic-oblong, united to the inner valve, 

 p. 310. 



AVENA. Cor. awned at the back, cloven, nearly cylindrical; inner valve 

 flat, ovate. Seed elliptic-oblong, united to the hard outer valve, p. 312. 



ARUNDO. Cor. surrounded with long permanent hairs. Florets 1 or 

 many. p. 313. 



* * * * Fl. aggregate, on a jointed, or toothed, common stalk, with lateral 

 excavations. 



ELYMUS. Cal. of 2 parallel valves, aggregate, with two or more florets. 

 p. 313. 



HORDEUM. Cal. of 2 parallel valve?, aggregate, ternate, with one floret. 

 Central flower only perfect, p. 314. 



TRITICUM. Cal. of 2 transverse opposite valves, solitary, many-flowered, 

 p. 315. 



