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 bulbosa, 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, except the aquatic ones (Glyceria) and P. maritima, 
have glabrous ribless blades with the median lines, and slight keel. 
P. pratensis, P. alpina and P. trivialis (Fig. 8) have entire 
sheaths (as have Glyceria fluituns, 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. fluitans have netted sheaths. 
Poa annua is annual, and P. bulbosa 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 
bulbosa has drier leaves than usual, but its leaves are devoid of 
ridges. 
** Ridges can be detected, but are slight and not distinct. 
Margins scabrid, at least at the base. 
+ Leaves firm, flat, linear, acuminate, not narrowed 
below. Glabrous. Ligule membranous. 
Digraphis arundinacea, Trin. (Reed-grass). Sheathed 
leaves round in .section; blades convolute, tapering above, 
