oe CLASSIFICATION ACCORDING TO [CH. 
The Bromes are extremely variable and difficult to determine by 
the leaves. The annual species are apt to be biennial or (B. sterilis) 
perennial; and some vary much as regards hairiness—e.g. B. mollis 
is connected by a series of semi-glabrous forms to varieties quite 
smooth, all grouped by Bentham under B. arvensis. 
Bromus asper, being auriculate and a shade-species, runs some 
risk of confusion with Hordeum sylvaticum, but Hordeum has a 
split sheath and in B. asper the translucent interspace between the 
ridges is 2—3 times as broad as in Hordeum sylvaticwm. 
The other species of Bromus are not eared, and their entire 
sheaths at once distinguish them from Hordeum. 
Bromus giganteus has leaves glabrous and very like Festuca 
elatior. The red split sheaths of the latter, its sharp ears and 
prominent ridges afford the best distinctions ; and B. giganteus has 
broader leaves and more evident serrulation or descending bristles 
at the basal margins. 
(2) Section of sheathed leaves elliptical, owing to the 
shoots being compressed. Sheaths often only slightly 
split above. No hair on surface of leaves or sheaths. 
* Margins of leaves smooth and even. Blades without 
ridges, a keel and flanking lines, acute, base rounded. 
Ligule of lower leaves very short. 
Poa pratensis, L. (Smooth-stalked Meadow-grass). 
An early and valuable dry pasture-grass, but though 
deep-rooted, it yields thin hay: its chief value is for 
“bottom grass” and in lawn mixtures, &c. Leaves stiff and 
pointed. Extra-vaginal rooting underground stolons, and 
intra-vaginal branches. Shoots smooth. Keel slight : seven 
principal veins and smaller ones between. Leaves blunter 
and broader than in P. trivialis. 
Poa alpina, L. (Alpine Poa). On mountains in the 
north. No stolons. 4—5 veins on each side of the median 
one. 
