POACEAE. 33 



Flowering scales with no crimped hairs at the base. 6. P. autumnalis. 

 Plants dull bluish green, with long stout often branch- 

 ing rootstocks : stems much compressed. 7. P. compressa. 



1. P. annua L. Stems 5-30 cm. tall: leaf -blades 1-10 cm. long, 1.5-3 mm. wide: 

 panicle 1-10 em. long, it branches spreading: spikelets 3-5-flowered, 3-5 mm. 

 long, the flowering scales 2.5-3 mm. long. Common, in cultivated grounds 

 and fields. Nat. of Eu. Spr.-f all. Low SPEAR-GRASS. 



2. P. trivialis L. Stems 3-9 dm. tall: leaf -sheaths very rough; blades 5-18 

 cm. long, 2-4 mm. wide, rough: panicle 1-1.5 dm. long: spikelets 2-3-flowered, 

 3 mm. long, the scales acute, the flowering scales 2-3 mm. long, 5-nerved, the 

 intermediate nerves prominent. Occasional, in waste places and meadows. 

 Nat. of Eu. Sum. 



3. P. pratensis L. Stems 3-12 dm. tall: leaf -blades 1-6 mm. wide, those on 

 the stem 5-15 cm. long, the basal much longer: panicle 6-20 cm. long, usually 

 pyramidal: spikelets 3 5-flowered, 4-5 mm. long, the scales acute, the flowering 

 scales 3 mm. long, 5-nerved. Common, in fields, pastures and woods. Nat. of 

 Eu. Sum. and fall. KENTUCKY BLUE-GRASS. 



4. P. brachyphylla Schult. Stems 3-9 dm. tall: leaf -blades 2-4 mm. wide, 

 abruptly acute, those on the stem 1-10 cm. long: panicle 613 cm. long, its 

 branches widely spreading or often reflexed, spikelet-bearing at the ends : spike- 

 lets 3-6-flowered, 57 mm. long, the flowering scales 4-5 mm. long, obtuse, the 

 intermediate nerves prominent. M. S. Bather rare, on rocky banks. Lime- 

 stones, schists. Spr. 



5. P. sylvestris A. Gray. Stems 3-9 dm. tall: leaf -blades 2-5 mm. wide, those 

 on the stem 4-15 cm. long, the basal much longer: panicle 7-18 cm. long, the 

 branches spreading or ascending, sometimes reflexed when old, spikelet-bearing 

 at the ends: spikelets 2-4-flowered, 2-4 mm. long, the flowering scales about 

 2.5 mm. long, obtuse. M. S. Eather rare, in damp woods. Limestones, 

 schists. Sum. 



6. P. autumnalis Muhl. Stems 3-9 dm. tall: leaf -blades 2 mm. wide or less, 

 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 35- 

 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. S. Bare, in woods. 

 Schists. Spr. 



7. P. compressa L. Stems 1.5-6 dm. tall: leaf -blades 2-10 cm. long, about 2 

 mm. wide: panicle usually contracted: spikelets 3-9 -flowered, 3-6 mm. long, the 

 flowering scales 2-2.5 mm. long, obscurely 3-nerved. Common, in cultivated 

 grounds, waste places, and woods. Nat. of Eu. Sum. and fall. CANADA 



BLUE-GRASS. 



43. PANICTJLABJA 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 plu- 

 mose. MANNA-GRASS. 



Lancaster County Flora 3. 



