Poa.] LXXXIX. GRAMINEJE. 539 



Spfkelets about 3- or 4-flowered. Flowering glumes 



strongly nerved 6. P. procumbent. 



Spikelete 6- or more flowered. Flowering glumes faintly 



nerved C. P. rigida. 



Panicle reduced to a single spike, with the lower spikelets occa- 

 sionally clustered. Root annual 7. P. loliacea. 



Panicle scarcely 1-sided, the branches and pedicels slender. 

 Flowering glumes all keeled, with minute silky hairs on 

 the keel or sides. 



Root annual. No hairs on the axis of the spikelet . . 8. P. annua. 

 Stock perennial. Minute woolly hairs on the axis under the 



flowering glumes. 



Panicle ovate or oblong, more or less crowded. 



Stem creeping at the base. Leaf-stalks much flattened . 9. P. compressor. 

 Stock tufted. Stems and lower sheaths thickened at the 



base. 



Stems bulbous at the base. Panicle contracted . . 15. P. bulbosa. 

 Stems scarcely bulbous. Panicle rather looso . . 14. P. alpina. 

 Panicle loose or very long. 

 Glumes pointed. Flowers about 3. 

 Panicle long. Spikelets oblong or lanceolate. 

 Stems weak. Leaves narrow and flaccid. Panicle 



slender . 12. P. nemoralis. 



Stems tall. Leaves long and stiff. Panicle very long 



and rather stiff Molinia ccerulea. 



Panicle very spreading, with slender branches, and few, 



rather large, ovate spikelets. (Alpine plant.) . . 13. P. laxa. 

 Flowering glumes rather obtuse. Panicle spreading, with 



numerous spikelets. 



Bootstock with creeping scions. Flowers about 4 in the 

 spikelet. Lateral nerves of the flowering glumes 



very faint 10. P. pratensis. 



No creeping scions. Flowers 2 or rarely 3 in the spike- 

 let. Lateral nerves of the flowering glumes con- 

 spicuous 11. P. trivialis. 



1. P. aquatica, Linn! (fig. 1236). Reed P. A stout, reed-like per- 

 ennial, 4 to 6 feet high, with a creeping rootstock. Leaves flat and 

 very rough on the edges. Panicle much branched, spreading, nearly 

 a foot long. Spikelets numerous, with 5 to 8 or 10 flowers. Outer 

 glumes unequal, thin, and 1-nerved. Flowering glumes about 1 lines 

 long, loosely imbricated, strongly 5- or 7-ribbed, rather obtuse, and 

 scarious at the top. Glyceria aquatica, Sm. 



In wet ditches, and shallow waters, throughout Europe and temperate 

 Asia, except the extreme north, and in North America. Frequent in 

 England and Ireland, rarer in Scotland. Fl. summer. 



2. P. fluitans, Scop. (fig. 1237). Floating P. An aquatic perennial, 

 often 2 or 3 feet high or more, with rather thick but weak stems, creep- 

 ing at the base ; the leaves often floating on the surface of the water. 

 Panicle erect and slender, a foot long or more ; the branches few and 

 usually erect. Spikelets few, ^ to 1 inch long, with from about 8 to 

 near 20 flowers. Outer glumes unequal, thin, and 1-nerved. Flower- 

 ing glumes loosely imbricated, 1^ to near 3 lines long, strongly 5- or 

 7-ribbed, scarious at the top, obtuse or slightly pointed. Glyceria 

 fluitans, Br. 



In wet ditches, and stagnant or slow-running waters, throughout 

 Europe and Russian Asia, except the extreme north, and in North 

 America. Common in Britain. FL all summer. [G. plicata, Fries., is 

 a variety with flowering glumes, twice as long as broad, and divaricate 

 fjruiting gpikeletsj 



