54 CLASSIFICATION ACCORDING TO [CH. 



(ii) Shoots terete or nearly so. 



Poa nemoralis, L. (Wood Poa). Leaves and sheaths 

 smooth. Blade bright green, thin, often glaucous, linear- 

 narrow, flaccid, acute. Ligule almost obsolete. Section 

 of shoots round. Of little value. 



Poa hulhosa, L. (Bulbous Meadow-grass). Stems 

 bulbous at the base. Ligule long and acute. Leaves 

 very narrow and tapering. Sections of shoot round. 

 Coasts of S. and E. 



All the Poas, excejDt the aquatic ones {Glyceria) and P. mariti'ma, 

 have glabrous ribless blades with the median lines, and slight keel. 



P. pratensis, P. alpina and P. tnvialis (Fig, 8) have entire 

 sheaths (as have Glyceria jVmtans^ G. aquatica and P. maritima)^ 

 but the others have them split some way down. 



The leaves of P. pratensis and P. compressa are firmer than the 

 thin leaves of P. annua, P. trivialis and P. nemoralis. 



Sheaths flattened in P. pratensis, P. compressa, P. annua, and 

 P. trivialis ', but rounded in P. nemoralis. Glyceria aquatica and 

 G. flvjitans have netted sheaths. 



Poa annua is annual, and P, hulhosa has the bulbous base. 

 P. maritima has involute leaves and no keel, and the rare P. alpina 

 has short rigid keeled mucronate leaves, with tip often inflexed and 

 thickened scabrid edges. 



The leaves of Avena are apt to appear similar to those of the 

 Poas at first sight, but the former are hairy, and ridged, dry as well 

 as thin, and the peculiar median lines of Poa are wanting. Poa 

 hulhosa has drier leaves than usual, but its leaves are devoid of 

 ridges. 



*■* Ridges can he detected, hut are slight and not distinct. 

 Margins scabrid, at least at the base. 



t Leaves firm, flat, linear, acuminate, not n/xrrowed 

 below. Glabrous. Ligule membranous. 



Digraplm arundihacea, Trin. (Reed-grass). Sheathed 

 leaves round in section ; blades convolute, tapering above, 



