For difficulties with other species of Avena and Poa see pp. [44,] [54] and [60.]
(b) Grasses with the leaves expanded, more or less flat.
(1) Blades conspicuously ridged—i.e. the surface is raised in prominent longitudinal ridges with furrows between.
(i) Leaves rigid and hard, sharp pointed. Sheath and outer leaf-surface usually glabrous.
Aira cæspitosa, L. (Tufted Hair-grass). Forms large tufts. A coarse weed forming bad tussocks in wet meadows and pastures: useless for fodder. Leaves flat. Ligule long, acute. Ridges equal, high and sharp, and scabrid, with 5-6 white lines between, if viewed by transmitted light. Wet meadows.
A. cæspitosa cannot easily be mistaken for any other species. Alopecurus geniculatus is also a moisture-loving grass with strongly ridged leaves, but the interspaces are far less translucent and the whole habit is different.
All the other species of Aira have involute and setaceous leaves, and even A. cæspitosa is apt to roll in its leaves in mountain varieties, but they are easily flattened out, and show the ridges.
Psamma arenaria, Beauv. (Sea Mat-grass). This is one of the most valuable “sand-binders," its long matted rhizomes holding loose sand together. It is a sea-shore grass, of no use for fodder. It was formerly much used for mats and thatching. Leaves concave, long, narrow, erect, scabrid and glaucous above, and polished below: pungent. Ridges rounded, alternately high and low. Sheath long. Ligule very long and bifid.
Elymus arenarius, L. (Sand Lyme-grass). Like Psamma, this is a “sand-binder" and of no use for fodder. Leaves concave, and eared at the base of the blade: ears pointed and tend to cross in front. Ligule very short and obtuse. Ridges flattened above, not scabrid. Apex of blade rolled, forming a hard spine.
Psamma cannot easily be mistaken for the much less common Elymus, as it is not eared, and the ridges and ligule are very different.
(ii) Leaves not specially rigid and hard, and often thin; glabrous, or shining below. Ridges less evident.
✲ Ligule very short or obsolete; blade firm but not hard, glabrous or nearly so, and shining below. Sheath often coloured red or yellow at the base.
† Sections of sheathed leaves narrow, oblong, owing to compression of shoots. Sheath nearly entire.
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.