TRIANDRIA DIGVNIA. 297 



a. Cor. unarmed. 



29. PASPALUM. Fl. m unilateral spikes. Cal. 2-valved, membrana- 

 ceous, equal, nearly orbicular. Cor. cartilaginous, of the size and 

 form of the calyx. Stig. plumose, colored. Nect. collateral 



30. MILIUM. Cal. 2-valved, herbaceous. Cor. 2-valved, coriaceous, 

 oblong, concave, shorter than the calyx, awnless. Seed 2-horned. 

 Nect. collateral. 



b. Cor. armed or bristled at the tip. 



31. PIPTATHERUM. Cal. membranaceous, longer than the corolla. 



Cal. cartilaginous, elliptical ; inferior valve awned at the tip. Nect. 

 ovate, entire. Seed coated. 



32. STIPA. cal. 2-valved, membranaceous. Cot. 2-valved, shorter 

 than the calyx, coriaceous, involute, subcylindric ; awn terminal, 

 contorted near the base. Seed coated. 



33. ARISTIDA. cal. 2-valved, membranaceous, unequal, cor. 2- 



valved, pedicellate, subcylindric ; inferior valve coriaceous, involute, 

 3-awned at the tip ; superior valve very minute, or obsolete. Nect. 

 collateral. 



2. Glumes and corolla of nearly similar texture, often carinate. 

 a. Panicle more or less spreading. 



34. MUHLENBERGIA. cal. very minute, 2-valved, truncate, unequal. 



cor. 2-valved, hairy at the base ; inferior valve terminating in a slen- 

 der bristle. 



35. TRICHODIUM. cal. 2-valved ; valves nearly equal, serrulate on 

 the keel. cor. 1-valved, smaller than the calyx. Stig. nearly ses- 

 sile. 



36. AGROSTIS. cal. 2-valved, 1-flowered, compressed, herbaceous 

 cor. 2-valved, membranaceous, generally larger than the calyx, often 

 hairy at the base. Nect. collateral. Seed coated. 



37. CINNA. cal. 2-valved, compressed, nearly equal, cor. linear, com- 

 pressed, shortly stipitate, naked at the base ; inferior valve enclosing 

 the superior, with a short awn near the summit. 



38. POLYPOGON. cal. 2-valved, 1-flowered; valves nearly equal, 

 terminating in a bristle, cor. 2-valved, shorter than the calyx ; the 

 inferior valve terminating in a bristle. 



39. TRICHOCHLOA. cal. 2-valved, 1-flowered; glumes very mi- 

 nute, 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. 



40. ARUNDO. cal. 2-valved, unequal, membranaceous, surrounded 

 with hair at the base ; inferior valve mucronate or slightly awned 

 superior valve sometimes with a pencil-form rudiment at the base. 



b. Panicle more or less contracted into a spike. 



41. PSAMMA. cal. 2-valved, awnless. cor. shorter than the calyx, 

 surrounded with hairs at the base. Nect. linear-lanceolate, longer 

 than the seed. Style 3-parted ; stig. 3. 



42. ALOPECURUS. cal. 2-valved, equal ; glum, generally connate 

 at the base ; cor. 1-valved, utriculate, cleft on one side, awned below 

 the middle ; styles often connate. 



43. PHLEUM. cal. 2-valved, much longer than the corolla ; glumes 



equal, boat-shaped, rostrate or mucronate ; cor. 2-valved, included in 

 the calyx, awnless, truncate. 



