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 glabréscens 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 em. long, 1-3 em. wide : spikelets 
5-9-flowered, the flowering scales 4-5 mm. long. 
On prairies, Indian Territory and Texas. Spring. 
11. Poa autumnáàlís Muhl. Stems 3-9 dm. tall: leaf-blades 2 mm. wide or less, 
smooth beneath, rough above, those on the stem 4-15 em. long, the basal much longer: 
panicle 7-22 em. 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. jlexuosa Muhl. ] 
In woods, New Jersey and Pennsylvania to Kentucky, Florida and Texas. Spring and summer. 
12. Poa praterícola 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 em. 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 qn 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 compréssa 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 distinetly 7-nerved. 
Panicle elongated, its branches erect or appressed. 2. P. elongata. 
xps not elongated, its branches usually spreading or ascending, sometimes 
rooping. 
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 elongata ( 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 nervàta (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 
