_Lolium perenne_, L. (Perennial Rye-grass). Very valuable pasture-grass, especially on clay. Less successful as hay. Deep rooted tufts. Glossy dark green. Ligule short (Fig. 11). Sheath red or purplish below. Blade conduplicate and keeled, often rounded, collared or eared at the base; with rounded ridges and rough above, shining below. When the ears are well developed their points often cross one over the other in front of the sheath. _L. italicum_, Braun. (Italian Rye-grass), is an earlier and better variety for hay and sewage farms. Shoot more rounded in section, and has less marked veins on the more rolled leaf. _L. temulentum_, L. (Common Darnel), is annual and a weed of corn-fields. Foliage usually rougher. _Lolium perenne_ presents some difficulties in relation to such forms as _L. italicum_, species of _Agrostis_ and _Festuca_, _Alopecurus pratensis_, _Cynosurus_ and _Agropyrum_. Owing to the leaves not being always strictly conduplicate in the first year, the flat shoots may not sharply mark it off from _L. italicum_. Its somewhat looser, almost stoloniferous tufts, and darker green foliage, less polished below and usually narrower and harder, have then to be taken into account. The ridges of _Lolium_ are often like those of _Festuca pratensis_; and the shining lower surface and rather firm leaves and red sheaths, present other points of confusion. The smooth basal margins of _Lolium_, absence of white translucent lines when held up, and the different ligule and ears afford distinctions--the ligule of _Festuca_ being a mere line, and the ears pointed and projecting, whereas they may be mere lateral ledges in _Lolium_. _Cynosurus_ has the ligule and ears very like those of _Lolium_, the ears being mere ledges; but the former has yellow sheaths, firmer and thicker leaves with more evident ridges, and the old plants usually have the characteristic crested spikes remaining. _Cynosurus_, moreover, has the sheath split only a short way down. With regard to _Agrostis_, there is no colour in the sheath, the ligule is longer and pointed, and the leaves drier and thinner than in _Lolium_, and harsher on both surfaces. _Agrostis_ has also no ears. _Alopecurus pratensis_ has much broader and flatter ridges than _Lolium_ and a longer ligule, and its sheaths are dark-brown or black--not red; but _A. agrestis_ has very similar ridges to _Lolium_ and may easily be confounded at first. _Agropyrum_ is sometimes nearly glabrous, and may then be confused with _Lolium_ by beginners: its low ridges, curled and pointed ears, obsolete ligule, and thinner, drier, harsher blade, as well as the stolons, distinguish it. _Lolium temulentum_ and _Hordeum murinum_ occasionally cause difficulty, but the latter is always more or less hairy, its blades thinner and drier, and the ridges less raised.