GEAMINEJ3. 605 



XXXV. POA. POA. 



Spikelets several- flowered (rarely only 2-flowered), awnless, numerous, in 

 a spreading or compact panicle. Outer glumes rather unequal, usually 

 keeled. Flowering glumes obtuse or pointed, but not awned, scarious at 

 the top, either keeled from the base or at the top only, or rounded to the 

 top without any prominent keel. 



A large genus, widely spread over all parts of the world. Although in 

 many respects a natural one, its characters and hmits are far from precise. 

 It differs fi"om Fescue only in its shorter glumes, without awns or decided 

 points, and some species have been placed alternately in the one or the other 

 genus. The first seven species are frequently separated, and formed into 

 one, two, or more genera, characterized by minute differences in the nerves 

 of tlie glumes or in the shape of the minute floral scales, or of the seed ; and 

 on the other hand, Catalrose, Molinia, Triodia, Cock's-foot, and Emleria, 

 although universally admitted, are distinguished by characters of very little 

 more value. In the present state of our acquaintance with the most prac- 

 tical principles of classification in Grasses, the limits of Poa, as retained in 

 the British Flora, appear to be the most natural. 



Tall, aquatic plants. Spikelets not much flattened. Flowering 

 glumes rounded on the back, with prominent veins, but not dis- 

 tinctly keeled. 

 Panicle large and spreading. Spikelets 3 to 5 Unas long . . .1. Heed P. 

 Panicle long and narrow. Spikelets erect, 6 lines to an inch long 2. Floating P. 

 Plants not aquatic. 

 Panicle one-s ded and stiff. Flowering glumes rounded on the 

 back, at least at the base. 

 Fanicle rather loose, i to 6 inches long. Glumes almost nerve- 

 less. Stork perennial. 

 Stem creeping at the base. Flowering glume about IJ lines 

 long. 



Leaf-sheaths much flattened 9. Flattened P, 



Leaf-sheaths not flattened 3. Sea P. 



Stems tufted. Flowering glumes about 1 Une long .... 4. Rejlexed P. 

 Panicle compact, seldom 3 inches long. Spikelets crowded. Root 

 annual. 

 Spikelets about 3- or 4-flowered. Flowering glumes strongly 



nerved 5. Procumbent P. 



Spikelets 6- or more flowered. Flowering glumes faintly 



nerved 6. Mard P. 



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

 sionally clustered. Root annual 7. Darnel F. 



Panicle scarcely one-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. Annual P. 



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. Flattened P. 

 Stock tufted. Stems and lower sheaths thickened at the . 

 base. 

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

 Stems scarcely bulbous. Panicle rather loose . . . .14. Alpine P. 

 Panicle loose or very long. 



Glumes pointed. Flowers about 3. 

 Panicle long. Spikelets oblong or lanceolate. 



Stemsweak. Leaves narrow and flaccid. Panicle slender 12. Wood F. 

 Stems tall. Leaves long and siiff. Panicle very long 



and rather stiif Purple Molinia, 



Panicle very spreading, with slender branches, and few, 



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



3i?2 



