41 



50. CYNOSURUS. 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. 



52. 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. 



54. AVENA. Cor. awned at the back, cloven, nearly 

 cylindrical ; inner valve flat, ovate. Seed elliptic-ob- 

 long, united to the hard outer valve. 



56. ARUNDO. Cor. surrounded with long permanent 



hairs. Florets 1 or many. 



**** Fl. aggregate, on a jointed, or toothed, common 

 stalk, with lateral excavations. 



57. LOLIUM. Cal. of 1 principal valve, opposite to the 



stalk, fixed, many-flowered. 



58. ROTTBOLLIA. Cal. of 2 parallel, sometimes com- 



bined, valves, opposite to the stalk, imperfectly 2- 

 flowered. 



61. TRITICUM. Cal. of 2 transverse opposite valves, 

 solitary, many-flowered. 



59. ELYMUS. Cal. of 2 parallel valves, aggregate, with 



2 or more florets. 



60. HORDEUM. Cal. of 2 parallel valves, aggregate, 



ternate, with \Jloret. Central Jloxvcr only perfect. 



Order III. TRIGYNU. Pistils 3. 



62. MONTIA. Cal. of 2 leaves. Cor. monopetalous. 



Caps, with 3 valves, and 3 seeds. 



64. POLYCARPON. Cal. of 5 leaves. Petals 5, nearly 

 entire. Caps, with 3 valves, and many seeds. 



63. HOLOSTEUM. Cal. of 5 leaves. Pet. 5, jagged. 



Caps, with 6 teeth, and many seeds. 



