728 GRAMINE./E AGROSTIB 



A. Howellii Scribn. Loosely tufted perennial : stems rather slender, 

 1-2 feet long: ligules about a line long, usually obtuse and lacerate at the 

 apex : panicle 4-8 inches long, its scabrous capillary branches 2-3 inches 

 long, usually spreading: empty glumes 1 line or less long, acuminate-lan- 

 ceolate; flowering glume lanceolate, acute, bearing a long slender bent awn 

 on its back : palet hyaline, minute. On cliffs along the Columbia river. 



A. scabra Willd. Sp PI. i, 370. Stem very slender, 1-2 feet high, 

 from a perennial root, smooth : sheaths generally shorter than the inter- 

 nodes: ligules 1-2 lines long: leaves 2-5 inches long, }-l^ lines wide, 

 usually erect, roughish: panicle 6-12 inches long, usually purplish, its 

 capillary branches spreading or ascending, or often drooping, the lower 3-6 

 inches long: empty glumes %-l line long, acute, scabrous toward the apex 

 and on the keel; flowering glume nearly as long as the outer ones, rarely 

 bearing a short awn on its back : palet very small. Common throughout 

 most parts of North America. 



A. Idahoensis Nash Bull. Torr. Bot. Club xxiv, 42. Stems cespitose, 

 slender, 8-16 inches high, erect, bearing usually 2 distant leaves below the 

 middle : lower sheaths short, the upper one elongated : ligules 1-2 lines 

 long, obtuse cut-toothed at the apex: leaves 2-5 inches long, erect, acu- 

 minate at the apex, rough on the margins : panicle oblong 3-6 inches long, 

 its .branches and pedicels scabrous above : empty glumes lanceolate and 

 acuminate, about 1 line long, scabrous on the keel, the first longer than 

 the second : flowering glume about % as long as the outer ones : palet 

 wanting. In forests, Idaho. 



A. varians Trin. Agrost. ii, 68. Stems slender, erect, densely cespi- 

 tose, 3-10 inches high : sheaths longer than the internodes : upper ligule 

 about ^ line long, acutisb : leaves very narrow, slightly scabrous above : 

 panicle 1-2 inches long, dark purple, its branches an inch or less long, 

 erect or ascending : empty glumes nearly equal, roughish on the keel 

 toward the apex, subacute; flowering glume nearly as long as the outer 

 ones, 2-toothed at the apex, awnless : palet wanting. In wet places on the 

 high mountains, Washington to California. 



A. Oregonensis Vasey. Stems slender, erect, 1-2 feet high, from a 

 perennial root : leaves flat, 2-3 inches long, the upper one usually longest : 

 ligules 1-2 lines long, acute : panicle long-exserted, 2-4 inches long, dark 

 purple, narrow, its capillary branches 1-2 inches long, erect : empty glumes 

 lanceolate, acuminate, about 1 line long; flowering glume hyaline, about 

 % as long as the outer ones, acute, not awned : palet wanting. In moist 

 meadows about the base of Mount Hood, Oregon. 



A. humilis Vasey Bull. Torr. Bot. Club x, 21. Stems densely cespi- 

 tose, 2-6 inches high, from perennial roots: sheath usually only one, 

 about % as long as the stem: ligules auriculate or 3-lobed, % line long: 

 leaves mostly basal, 1-3 inches long, less than a line wide, erect: panicle 

 narrow, 6-18 lines long, dark purple, its very few branches erect or appres- 

 sed: empty glumes equal, lanceolate, acute, smooth, %-\ line long; flow- 

 ering glume nearly equalling the outer ones, lanceolate, minutely toothed 

 at the apex: palet ovate-oblong. In wet meadows on high mountains, 

 Washington to the Rocky Mountains. 



A. yirescens HBK. Nov. Gen. i, 135. Stems 1-2 feet high, from a 

 perennial root : sheaths much shorter than the internodes mostly smooth : 

 tigules more than a line long, truncate: leaves flat, erect, about 6 inches 

 long by 4 lines wide, rough on both sides: panicle pale greenish tinged 

 with purple, about 6 inches long, its branches in clusters about an inch 

 apart on the common axis : empty glumes very acute, the lower terminated 

 by a distinct seta, rough on the keel and pubescent all over; flowering 

 glume about % shorter than the empty ones, bearded at base by a few 

 short white hairs, 5-nerved, the lateral nerves projecting as distinct teeth, 



