IB TRIANDRIA.— DIGYNIA. 



ferior valve coriaceous, involute, 3-awned at the 

 tip ; superior valve very minute, or obsolete. JVect. 

 collateral. 



.. Glumes and corolla of nearly similar texture, often ca- 

 rinate. 



cc. Panicle more or less spreading. 



51.MUHLENBERGIA. Cal. very minute, 2-valved, 

 truncate, unequal. Cor. 2-valved, hairy at the base ; 

 inferior valve terminating in a slender bristle. 



52. TRICHODIUM. Cal. 2-valved ; valves nearly 



equal, serrulate on the keel. Cor. 1-valved, smaller 

 than the calyx. Stig. nearly sessile. 



53. AGROSTIS. Cal. 2-valved, 1 -flowered, com- 



pressed, herbaceous. Cor. 2-valved, membra- 

 naceous, generally larger than the calyx, often hairy 

 at the base. JVect. collateral. Seed coated. 



54. CINNA. Cal. 2-valved, compressed, nearly equal. 



Cor. linear, compressed, shortly stipitate, naked at 

 the base ; inferior valve enclosing the superior, with 

 a short awn near the summit. 



55. POLYPOGON. Cal. 2-valved, 1 -flowered ; valves 



nearly equal, terminating in a bristle. Cor. 2-val- 

 ved, shorter than the calyx ; the inferior valve ter- 

 minating in a bristle. 



56. TRICHOCHLOA. Cal. 2-valved, 1-flowered ; 



glumes very minute. Cor. much larger than the 

 calyx, 2-valved, naked at the base ; inferior valve 

 convolute at the base, terminating in a long awn 

 not articulated. 



57. ARUNDO. Cal. 2-valved, unequal, membranaceous. 



surrounded with hair at the base ; inferior valve 

 mucronate or slightly awned ; superior valve some- 

 times with a pencil-form rudiment at the base. 

 /3. Panicle more or less contracted into a spike. 



■3'8. PSAMMA. Cal 2-valved, awnless. Cor. shorter than 

 the calyx, surrounded with hairs at the base. JVect. 

 linear-lanceolate, longer than the seed. Style 3- 

 parted ; stig. 3. 



39. CRYPSIS. Cal. valved, membranaceous, carinate. 

 Cor. longer than the calyx, which it resembles in 

 texture and form. Stam. 2—3. JVect. 0. 



