_Arrhenatherum_ (sheath keeled). _Poa_ (all except _P. maritima_). _Dactylis._ _Bromus._ _Bromus asper_ (sheath keeled, often a white line). _Holcus lanatus_ (slight and decurrent) (Fig. 15). _Digraphis_ (Fig. 14). _Glyceria._ Most grasses are glabrous, but there are a number in which hairs are nearly always a prominent feature. It must be remarked, however, that with grasses, as with other plants, the character of pubescence is apt to vary with the situation. In general it may be stated that a hairy grass tends to become more glabrous in a moist situation, and more pubescent in a dry one, but the rule is by no means absolute. In some cases,--e.g. _Avena pubescens_, _A. flavescens_, _Agropyrum_, the hairs are almost entirely confined to the crests of the ridges (Figs. 10, 15). The following is a list of hairy grasses. HAIRY GRASSES. _Holcus_ (Fig. 15). _Molinia cærulea._ _Brachypodium sylvaticum._ _Agropyrum_ (variable). _Bromus asper._ _B. mollis._ _Hordeum._ _Anthoxanthum._ _Avena flavescens_ (Fig. 10). _A. pubescens._ _Triodia._ _Kœleria._ To a less extent. _Festuca sciuroides_ (on ribs). _Melica._ Grasses as a rule are devoid of strong scents[5] or tastes, but _Anthoxanthum_ has a faint but distinct sweet odour, especially as it dries--it is one of the grasses which give the scent to new-mown hay--and a bitter flavour, and _Milium_, _Hierochloe_ and _Holcus_ are also more or less bitter. _Spartina stricta_ emits a strong unpleasant odour. The habitat of grasses is of great importance as an aid to determination. No one would expect to find a sea-shore grass growing in a beech-forest, or an aquatic grass on a dry chalk-down; but they are even more true to their habitats than this, and I append the following lists of habitats of British grasses as of use in determining them, though it is not pretended that the limits are absolute. In the following list “pasture-grass” (P) means useful for grazing, and “meadow-grass” (M) one that is especially valuable for mowing--i.e. for hay. A “weed” (W) is used in its agricultural sense for a grass not useful and not wanted on cultivated land, though often found there. MEADOW-AND PASTURE-GRASSES.