Bromus asper, Murr. (Hairy Brome). In thickets, &c.: a weed, and useless. Leaves green, long, flat, hanging, and eared. Sheath with scattered deflexed hairs. Lamina tapering at the base. Keel a white line, ridges inconspicuous: distance between veins 2-3 times breadth of latter. Ligule very short, toothed.
B. giganteus, L. (Tall Brome), also comes here. It is less common and glabrous. Woods, &c., a useless weed.
✲✲ Annual or biennial.
Bromus mollis (B. arvensis, var. mollis, L.), Field Brome. A too abundant and useless weed in water-meadows and hay-fields. Softly downy. Blades very thin and not eared: dry.
Bromus sterilis, L. (Barren Brome). A useless weed. Rough and downy, but less so than the last. Moist waysides, &c.
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 sylvaticum.
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.