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. _Poa pratensis_ presents similar difficulties to _P. trivialis_: for diagnoses see p. 42. It is distinguished from _P. nemoralis_ by its closed sheath, thicker, blunter and harder leaves, linear-elliptical shoot-sections, and light coloured nodes, as well as by its habit. All other Poas have shallow and poorly developed roots. _P. fertilis_ is a form very like _P. nemoralis_, with rougher leaves and longer ligule, introduced into cultivation. ✲✲ _Margins of leaves scaberulous with descending hairs. Very low flat ridges. Sheath smooth._ _Briza media_, L. (Quaking Grass). A weed in meadows, indicating poor soil--e.g. moor-lands and chalk--but eaten by sheep. Tufted and slightly creeping perennial. Ligules very short, entire. _Briza minor_, L. (Lesser Quaking-grass). Annual. Leaves broader and shorter, and ligules longer. In the south and rarer. II. SHEATHS SPLIT, AT LEAST SOME DISTANCE DOWN. +A. Glabrous--i.e. with no obvious hairs[7].+