154 POACEAE 



branches erect or nearly so : spikelets numerous, 4-7 -flowered, the scales acuminate, the 

 flowering scales 4-5 mm. long. 



On prairies, Kansas to New Mexico, Louisiana and Texas. Also introduced into Florida. Spring. 



10. Poa glabr6scens Nash. Stems tufted, 2-5 dm. tall : leaf -blades erect, 1.5 dm. 

 long or less, 2-5 mm. wide, rough above : panicle 4-15 cm. long, 1-3 cm. wide : spikelets 

 5-9-flowered, the flowering scales 4-5 mm. long. 



On prairies, Indian Territory and Texas. Spring. 



11. Poa autumiialis Muhl. Stems 3-9 dm. tall : leaf-blades 2 mm. wide or less, 

 smooth beneath, rough above, those on the stem 4-15 cm. long, the basal much longer : 

 panicle 7-22 cm. long, the branches long and slender and spikelet-bearing at the ends : 

 spikelets 3-5-flowered, 5-6 mm. long, the flowering scales rounded or retuse at the apex, 

 3-4 mm. long, pubescent on the lower part of the internerves. [P. flexuosa Muhl. ] 



In woods, New Jersey and Pennsylvania to Kentucky, Florida and Texas. Spring and summer. 



12. Poa pratericola Rydb. & Nash. Stems 3-6 dm. tall, erect, rigid : leaf-sheaths 

 usually overlapping ; ligule 2-4 mm. long, acute ; blades smooth beneath, rough above, 

 1-2 mm. wide, flat or folded, pungently pointed, those on the stem 1-2.5 cm. long, erect, 

 the basal ones 7-15 cm. long : panicle contracted, 5-13 cm. long, the branches erect : spike- 

 lets 4-7-flowered, 5-7 mm. long, the flowering scales 3-4 mm. long, erose-truncate at the 

 apex, strongly silky -pubescent on the nerves for J their length, the internerves pubescent 

 below, the intermediate nerves very obscure. 



In meadows and low grounds, Northwest Territory to Kansas, the Indian Territory and Arizona. 

 Spring and summer. 



13. Poa comprssa L. Stems 1.5-6 dm. tall, decumbent at the base, from long 

 branching rootstocks, much flattened : leaf-sheaths loose, flattened ; blades 2-10 cm. long, 

 about 2 mm. wide : panicle usually contracted, the branches erect or ascending : spikelets 

 3-9-flowered, 3-6 mm. long, the flowering scales 2-2.5 mm. long, obscurely 3-nerved. 



In cultivated grounds, waste places and woods, almost throughout North America. Naturalized 

 from Europe, at least in some places. Also a native of Asia. Summer. CANADIAN BLUE GRASS. 



112. PANICULARIA Fabr. 



Usually perennial, rarely annual, sometimes aquatic grasses, with commonly flat leaf- 

 blades and open or contracted panicles, the branches sometimes drooping. Spikelets usually 

 numerous, ovate to linear, few-many-flowered, the glabrous rachilla articulated between 

 the perfect flowers, the upper flowers sometimes imperfect. Scales few-many, awnless, the 

 2 lower empty, obtuse or acute, unequal, the flowering scales longer, obtuse to truncate and 

 denticulate, rarely acute or acuminate at the more or less hyaline apex, convex on the back 

 but not keeled, usually prominently nerved, the nerves vanishing at the hyaline margin ; 

 palet 2-keeled, equalling or shorter than, rarely exceeding, the scale. Stamens 3. Style 

 short, distinct. Stigmas plumose. [Glyceria R. Br.] MANNA GRASS. 



Spikelets ovate or oblong, 8 mm. long or less. 



Flowering scales very broad, obscurely or at least not sharply nerved. 1. P. obtusa. 



Flowering scales narrow, sharply and distinctly 7-nerved. 



Panicle elongated, its branches erect or appressed. 2. P. elongate. 



Panicle not elongated, its branches usually spreading or ascending, sometimes 



drooping. 

 Flowering scales about 1.5-2 mm. long, obtuse or rounded at the apex. 



Spikelets 2-3 mm. long or less : branches of the panicle often drooping. 3. P. nervata. 

 Spikelets 4-6 mm. long : branches of the panicle ascending or spreading. 4. P. Americana. 

 Flowering scales 2.5-3 mm. long, truncate and denticulate at the apex. 5. P. pallida. 



Spikelets linear, 12 mm. long or more. 



Flowering scales 4-5 mm. long, obtuse, equalling or exceeding the obtuse palet. 6. P. fluitans. 

 Flowering scales 6-8 mm. long, acute, much shorter than the acuminate palet. 7. P. acutiflora. 



1. Panicularia obtusa (Muhl.) Kuntze. Stems 3-9 dm. tall, erect, stout, rigid: 

 leaf -sheaths strongly striate, the lower overlapping ; blades 1.5-4 dm. long, 4-8 mm. wide, 

 usually stiff, erect or ascending, rough above : panicle 7-20 cm. long, contracted, dense, 

 the branches erect : spikelets 3-7-flowered, 4-6 mm. long, the flowering scales 3 mm. long. 



In swamps, New Brunswick to New York, Delaware, Maryland and North Carolina. Summer. 



2. Panicularia elpngata (Torr. ) Kuntze. Stems 6-9 dm. tall : leaf -blades lax, 1.5-3 

 dm. long, 3-6 mm. wide, long-acuminate, rough above : panicle elongated, contracted, 

 usually nodding at the summit, 1.5-3 dm. long, the branches erect or appressed : spikelets 

 3-4-flowered, 3-4 mm. long, the flowering scales about 2 mm. long, obtuse or acutish. 



In wet woods and swamps, Newfoundland to Quebec, Minnesota, Kentucky and North Carolina. 

 Summer and fall. 



3. Panicularia nervata (Willd. ) Kuntze. Stems 3-9 dm. tall : leaf-sheaths usually 

 rough ; blades 1.5-3 dm. long, 4-10 mm. wide, rough above: panicle 7-20 cm. long, often 



