Rootstock shortly creeping, branches extra-vaginal and above ground, shoots rough. Blade narrow, harsh, with an acute point, thin, shining below, ridgeless, with flanking lines and keel. Ligule acute, and short or long (Fig. 8). _Sesleria cærulea_, Ard. (Blue Moor-grass), of our northern limestone hills, has narrow, flat, glaucous blue, stiff, mucronate leaves, with scabrid apex. Ligule ciliate. _Poa trivialis_ is most likely to be confounded with other Poas, especially _P. annua_ and _P. pratensis_, since they both have thin leaves and flat shoots; but _P. annua_ has a split sheath, less acute and duller leaves, is annual, and less harsh, and the shoot-section is flatter at the sides and rounder at the ends. _Poa pratensis_, L. is larger and more stoloniferous, with both extra- and intra-vaginal branches, culms erect and smooth, sheaths smooth, and the shoot-sections elliptical--not cornered or rhomboidal--and with darker green and larger, thicker, 7-veined, more glossy, and less harsh leaves, with shorter, blunter ligule. _Poa compressa_, L. also presents difficulties, but the sheath is split, and the ligule is shorter than in _P. trivialis_, the leaves thicker, and the shoot-sections more linear-oblong or elliptical. (β) Sections of sheathed leaves rounded, circular or oval, there being no prominent keels. (1) Section of sheathed leaves circular or nearly so, the shoots being only slightly compressed. * _Perennial._ _Bromus inermis_ (Awnless Brome). Sections circular, the leaves being convolute, base shelving. Glabrous sheaths and leaves. Stoloniferous. Ligule short, truncate, and finely toothed. A forage grass of the Hungarian steppes. Now being grown in this country, but of doubtful value here. _Bromus erectus_, Huds. (Upright Brome). A weed. Sections oval and rounded, but leaves equitant. Radical leaves remain folded and almost subulate, hairy edges. No stolons. Fields, &c. It is a weed on dry lands, and of little or no value. _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.