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. moorlands 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].
(a) Grasses with setaceous or bristle-like leaves;—i.e. the lamina of the lower leaves remains permanently folded instead of opening out flat.
(1) Ligule obsolete, auricled at the junction of blade and sheath.
Festuca ovina (Sheep’s Fescue). Densely tufted perennial. Leaves hard, glabrous and often glaucous, with 5-7 ridges if forcibly unrolled, ears short, stiff and erect. Branches in permanent sheaths. Chiefly useful as pastures on downs and dry chalk-soils. Several varieties are recognised by agriculturists, as hard, red, various-leafed, fine-leafed Fescue, &c. (see Figs. [13] and [18]).
Festuca Myurus, L. (Rat’s-tail Fescue). Annual, longer auricles, and hair on the ribbed inrolled surface. A roadside weed.
Festuca ovina presents difficulties with its varieties and with F. Myurus, L. (var. sciuroides, Roth.).
The chief varieties of F. ovina are Hard Fescue (F. duriuscula, L.), taller and with some of the upper leaves flat, and found in moister and rich soils: Red Fescue (F. sabulicola, Duf. or F. rubra, L.) more or less creeping and with red sheaths to the lower leaves, on poor stony land—F. heterophylla is a form of this on chalky soils, with flat leaves above: and F. tenuifolia a very wiry form on sheep-lands. They all pass into one another, however, and cannot be distinguished by the leaves (see Figs. [18]-20).
F. Myurus (var. sciuroides) is ruderal and annual, and has longer hairs on the ridges of the folded leaves. It has no agricultural value.
(2) Ligule membranous, not auricled.
(α) Bristle-like (setaceous) leaves, very hard and stiff, and more or less solid.