CHAPTER III.

GRASSES CLASSIFIED ACCORDING TO THEIR VEGETATIVE CHARACTERS.

I. SHEATHS ENTIRE EXCEPT WHERE THOSE OF LOWER LEAVES ARE BURST BY BRANCHES, &C.

+A. Aquatics with the sheaths reticulated, owing to large air-cavities. Leaves equitant, linear acute, often floating.+

_Glyceria fluitans_ (Br.). Floating sweet grass. Somewhat coarse, but useful pasture in water-meadows and fens. Sweet-tasting.

Section of sheathed leaves linear oblong; sheath striate or furrowed, keeled; leaf ribbed; ligule broad acute. Leaf-base with a yellow triangle. Smooth.

_Glyceria aquatica_ (Sm.). Reed sweet grass. Especially given to growing in the water-courses and on banks instead of spreading in the water-meadows, &c. Sweet-tasting.

Section of sheathed leaves broadly naviculate; sheath smooth, no keel; leaf not ribbed, thick and inflated with large air-cavities; ligule short. Leaf-base with a brown triangle. Margins and keel rather rough.

These two species of _Glyceria_ are distinguished by their shoot-sections and the ridges of the leaves of _G. fluitans_: they often occur in the same ditch.

They cannot readily be confused with others on account of their aquatic habit, and the characters given. The only other aquatic or semi-aquatic species are forms of _Catabrosa_, _Digraphis_, _Arundo_, _Alopecurus geniculatus_, _Molinia cærulea_ and the rare _Calamagrostis_.

The ligule and flat shoots with closed sheaths alone suffice to distinguish it from the round and split sheathed _Arundo Phragmites_; and the round shoots of _Digraphis_, its split sheath and firm leaves, suffice to distinguish it.

_Molinia_ also has a tuft of hairs instead of a ligule, and a split sheath, and its habit is different.

_Alopecurus geniculatus_, with its “kneed” shoots, has a totally different habit from _Glyceria_, and its very high ridges and want of visible air-chambers complete the diagnosis.

_Catabrosa_ is a small creeping aquatic with very flaccid leaves, quite glabrous and soft. Also sweet-tasting.

+B. Not aquatic, and devoid of visible air-chambers in leaf or sheath. Often perennial, i.e. having stolons or other branches with no rudiments of flowers in them, and with relics of old leaf-bases.+

(α) Sections of sheathed leaves acute: either two-edged or four-edged.

(1) Section of sheathed leaves quadrangular. Blades of leaf thin and dry, sparsely hairy. Sheath quite entire. Woods and shady places.

_Melica uniflora_, L. (Wood Melick). Lamina slightly tapered below, convolute. Ligule obsolete, with a stiff subulate process on the sheath opposite the blade-insertion. Ridges below, but not above.

_Melica nutans_, L. (Mountain Melick). Ligule longer, and without the awl-shaped peg. Only in Scotland and W. of England.

Both are shade grasses of no agricultural value.

_M. uniflora_, with its quadrangular shoots and anti-ligular peg, cannot be confounded with any other grass.

(2) Sections of sheathed leaves more or less acutely two-edged, owing to the keels of the compressed equitant leaves.

(i) _Shoots broad and fan-like, much compressed, with old brown leaf-sheaths below, sometimes burst by the intra-vaginal branches: leaf ridgeless, with prominent keel. No underground stolons._

_Dactylis glomerata_, L. (Cock’s-foot). An early and quick-growing pasture-grass, which forms much aftermath. Grows on all soils. Often coarse. Coarse tussocks, and harsh, with broad thick succulent bluish-green leaves.

Section of sheathed leaves acutely naviculate. Prominent obtuse ligule, torn above. Lamina long, rough, acute, with white lines if held up, and serrulate edges. No flanking lines[6]. No stolons (Fig. 6).

There is a cultivated variety of _Dactylis_ with broad opaque white stripes down the leaves: these are totally different from the translucent white stripes seen on holding the wild form, or _Aira cæspitosa_, up to the light. Another cultivated “ribbon-grass”--_Digraphis_--has _round_ shoots, _split_ sheaths, and a different habit, and the same applies to its wild form.

Probably the only serious chances of confusion with _Dactylis_ are between it and _Poa pratensis_, which also has flattened shoots and closed sheath; but in the latter the section of the shoot is _elliptical_--not _naviculate_,--the keel is far less prominent, and the ligule shorter. Moreover _P. pratensis_ is a creeping stoloniferous grass, less harsh, and with less pointed leaves.

The distance to which the sheath is torn may be from 1/8 to 1/2 down. Leaves tend to remain conduplicate. Margins serrulate with teeth extremely short and directed forwards.

(ii) _Shoots compressed but narrow: the section almost rhomboid with rounded edges._

_Poa trivialis_, L. (Rough-stalked Meadow-grass). Conspicuous in deep rich pastures and orchards, preferring slight shade and rich soil. Valuable pasture and hay grass.

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.

The Bromes are extremely variable and difficult to determine by the leaves. The annual species are apt to be biennial or (_B. sterilis_) perennial; and some vary much as regards hairiness--e.g. _B. mollis_ is connected by a series of semi-glabrous forms to varieties quite smooth, all grouped by Bentham under _B. arvensis_.

_Bromus asper_, being auriculate and a shade-species, runs some risk of confusion with _Hordeum sylvaticum_, but _Hordeum_ has a _split_ sheath and in _B. asper_ the translucent interspace between the ridges is 2-3 times as broad as in _Hordeum sylvaticum_.

The other species of _Bromus_ are not eared, and their entire sheaths at once distinguish them from _Hordeum_.

_Bromus giganteus_ has leaves glabrous and very like _Festuca elatior_. The red split sheaths of the latter, its sharp ears and prominent ridges afford the best distinctions; and _B. giganteus_ has broader leaves and more evident serrulation or descending bristles at the basal margins.

(2) Section of sheathed leaves elliptical, owing to the shoots being compressed. Sheaths often only slightly split above. No hair on surface of leaves or sheaths.

✲ _Margins of leaves smooth and even. Blades without ridges, a keel and flanking lines, acute, base rounded. Ligule of lower leaves very short._

_Poa pratensis_, L. (Smooth-stalked Meadow-grass). An early and valuable dry pasture-grass, but though deep-rooted, it yields thin hay: its chief value is for “bottom grass” and in lawn mixtures, &c. Leaves stiff and pointed. Extra-vaginal rooting underground stolons, and intra-vaginal branches. Shoots smooth. Keel slight: seven principal veins and smaller ones between. Leaves blunter and broader than in _P. trivialis_.

_Poa alpina_, L. (Alpine Poa). On mountains in the north. No stolons. 4-5 veins on each side of the median one.

_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. moor-lands 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 road-side 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._

_Nardus stricta_, L. (Moor Mat-grass). Roots very tough and stringy: ligule small, but thick and blunt. Leaves channelled: upper erect, lower horizontal. Sheath smooth. Moors and sandy heaths: useless (Figs. 2 and 26).

_Aira flexuosa_, L. (Wavy Hair-grass). Roots fibrous. Leaves short, filiform, terete, solid--the channel hardly discernible. Ligule short, obtuse. Heaths, &c. Of little use, even for sheep (Fig. 28).

(β) _Leaves bristle-like, but distinctly due to inrolling of edges._

_Aira caryophyllea_, L. (Silvery Hair-grass), is scabrid. A weed, with very slight foliage.

_A. præcox_, L. (Early Hair-grass). Greener and more glabrous. Habit more rigid.

_A. canescens_, L. (Grey Hair-grass). Glaucous or purplish; rare, on S.E. coasts.

(γ) _Leaves narrow and more or less involute, and subulate upwards, but easily unrolled, and apt to become flatter as they age._

_Avena pratensis_, L. (Perennial Oat). Leaves rather thin, dry, harsh, ridgeless, with flanking lines and a keel[8]; glaucous, glabrous, but edges scabrous. Usually involute, but may open out. Ligule long ovate-acute. Dry pastures, especially on calcareous soil, and of little value.

_Poa maritima_, Huds. (Sea-grass). Leaves narrow, rather short, and U-shaped in section. Involute: ridgeless, with flanking lines, but no keel; soft and rather thick. Ligule rather long, obtuse and decurrent. Useless agriculturally.

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.

_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.

†† _Sections rounded--elliptical or nearly circular. Sheath distinctly split, at least above._

_Cynosurus cristatus_, L. (Crested Dog’s-tail). Useful as pasture on dry soils, but only moderately so as hay. Blade narrow, slightly eared or collared below, tapered above; firmer than _Lolium_. Sheath only split a short way down. Yellow or yellowish-white at the base. Leaves conduplicate or convolute, short and narrow, the ligule short: minute ears at base. Usually easily recognised by the withered culms and persistent pectinate spikes (Fig. 16).

_Festuca elatior_, L. (Meadow Fescue). A valuable meadow and pasture grass, though somewhat coarse. Several varieties are known. Best on heavy soils. Deep rooted. Blade flat and broad, conduplicate, sharp-eared at the base, and there rough at the margin: lower surface polished. Rich green. Mid-rib flat above, numerous ribs with white lines between if held up and examined with a lens. Ligule obsolete (Figs. 12 and 17).

_Arundo Phragmites_, L. (Common Reed). A large aquatic, reed-like creeping grass, with broad leaves (3/4 to 1 in.), flat, rather rigid, acuminate, glaucous below, hispid at edges. Sheath smooth, striate, bearded at mouth. Ligule a mere fringe of hair. (Cf. _Digraphis_, p. 54.)

_Cynosurus_ is not very liable to confusion; but it has resemblances to _Lolium_ (see p. 49) and to species of _Agrostis_. The leaves of _Cynosurus_ are firmer, thicker, less dry, and with a shining undersurface, and the sheath is only split above, and yellow below; whereas _Agrostis_ has relatively thin and dry leaves, rough surfaces and margin, distinct ridges, and converging margins as the blade nears the sheath.

_Festuca elatior_ is easily confused with the glabrous Bromes. For _B. giganteus_ see p. 43.

_Bromus erectus_ is distinguished by the entire sheath, usually hairy, the want of auricles, and the conduplicate--not convolute--leaves.

_Agrostis_ has thinner, duller, and drier leaves, and no red sheath.

_Alopecurus pratensis_ has more depressed, flatter and broader ridges than _Festuca_, and a longer ligule, and lacks the pointed ears.

** _Ligule whitish, membranous, long, or at least well developed. Sheaths not coloured or brown. Leaves thin and rough, at least at the base. Ridges not very prominent, but numerous and distinct._

_Agrostis stolonifera_, L. (Fiorin). Stolons, with numerous short offsets bursting through the leaf-sheaths. Blade flat, rough, tapering, with rounded ridges, and convolute in bud: there are no auricles, but the blade may narrow, and form ledges, as it runs into the sheath. Sheaths nearly smooth. Ligule long and pointed, and often toothed at the margins. The leaves vary in breadth.

This and _A. vulgaris_, With. with shorter ligules, and, possibly, _A. canina_, L. with finer leaves, are varieties of _A. alba_, L. Only the variety _A. stolonifera_ is of moderate value for pasture, especially on poor soils, as it lasts late into autumn: the others are weeds, like couch-grass.

_Agrostis_ is full of difficulties for the beginner. The weed-forms often spring up after wheat has been cut, and count as “twitch,” like _Agropyrum_.

All the ordinary forms--_A. stolonifera_, _A. vulgaris_, and _A. canina_--may be included in _A. alba_ (Linn.). On dry hills a close tufted grass, with setaceous leaves, and in rich soils creeping and luxuriant with broad leaves. It is one of the few grasses that thrive in wet soils.

The chief points in the flat-leafed forms are the thin, dry leaves, rough on both sides and on the margins, with distinct raised ridges, and the base of the leaf narrowing suddenly into its insertion with the sheath, with no auricle, but with a long membranous ligule. The sheath not coloured, and the blade convolute.

Again, _A. stolonifera_ has a long, serrated, acute ligule, while _A. vulgaris_ has a much shorter, entire and truncate one, and narrower leaves.

_Agropyrum_ is the grass most likely to lead to confusion. Its ears, lower ridges, very short or obsolete ligule, and pubescence (sometimes glabrous) distinguish it.

_Cynosurus_ sometimes gives trouble (see p. 50) with _Alopecurus pratensis_: the sheaths, ligule and flattened ridges should suffice for distinction.

_Alopecurus geniculatus_ is even more like _Agrostis_, but its ridges are more prominent and sharp, and its aquatic habit and bent “knees” distinguish it.

_Alopecurus agrestis_, in dry corn-fields, has a thickened ligule, sometimes coloured, and is annual or biennial, but otherwise very like _Agrostis_.

_Alopecurus pratensis_, L. (Meadow Foxtail). Large grass with stolons; very early, and much prized as pasture and hay, but soon dies out on light poor soils. Especially good for stiff soils. Sheaths long, ridged, brown or nearly black at the base as they age. Ligule distinct and obtuse, entire. Leaves numerous. Blades long, dark green, succulent and scabrous: ridges numerous and flat above, but distinct (Fig. 9).

_A. agrestis_, L. in S. England has shorter leaves, and ridges not flattened; it is a troublesome pest of arable land, but does not usually invade pasture.

_A. geniculatus_, L. is semi-aquatic, and like the last. It is easily recognised by its sharply bent “knees,” and is of little value (Fig. 3).

_Alopecurus_ shows resemblances to _Lolium_ (see p. 49), _Festuca_ (see p. 50), and _Agrostis_ (see p. 52). If well grown its ridged sheath and leaves, the former brown or black at the base, aid in distinguishing it.

(2) Blades either devoid of ridges or with very inconspicuous ones.

* _No trace of ridges, and the mid-ribs not prominent, but the leaves show median lines flanked by finer ones when held up. Blades thin and narrow. Somewhat keeled._

(i) _Shoots compressed._

_Poa compressa_, L. (Flat-stemmed Meadow-grass). Leaves rather short, more or less glabrous or glaucous, and +V+-shaped at the base; shoots compressed, and naviculate in section. Ligule short and thin. Sheath tends to be closed below. A creeping perennial on commons and waste lands, and of little or no value.

_Poa annua_, L. (Annual Meadow-grass). Small annual. Compressed shoots, limp. Leaves linear, pale, sub-acute, thin, often wavy, flat, flaccid, bright green; dull or slightly shining and +V+-shaped in section below. Ligule long, pointed, whitish and clasping the shoot. It is a harmless weed, and since it puts out shoots all the year round, furnishes a certain amount of pasturage.

(ii) _Shoots terete or nearly so._

_Poa nemoralis_, L. (Wood Poa). Leaves and sheaths smooth. Blade bright green, thin, often glaucous, linear-narrow, flaccid, acute. Ligule almost obsolete. Section of shoots round. Of little value.

_Poa bulbosa_, L. (Bulbous Meadow-grass). Stems bulbous at the base. Ligule long and acute. Leaves very narrow and tapering. Sections of shoot round. Coasts of S. and E.

All the Poas, except the aquatic ones (_Glyceria_) and _P. maritima_, have glabrous ribless blades with the median lines, and slight keel.

_P. pratensis_, _P. alpina_ and _P. trivialis_ (Fig. 8) have entire sheaths (as have _Glyceria fluitans_, _G. aquatica_ and _P. maritima_), but the others have them split some way down.

The leaves of _P. pratensis_ and _P. compressa_ are firmer than the thin leaves of _P. annua_, _P. trivialis_ and _P. nemoralis_.

Sheaths flattened in _P. pratensis_, _P. compressa_, _P. annua_, and _P. trivialis_; but rounded in _P. nemoralis_. _Glyceria aquatica_ and _G. fluitans_ have netted sheaths.

_Poa annua_ is annual, and _P. bulbosa_ has the bulbous base. _P. maritima_ has involute leaves and no keel, and the rare _P. alpina_ has short rigid keeled mucronate leaves, with tip often inflexed and thickened scabrid edges.

The leaves of Avena are apt to appear similar to those of the Poas at first sight, but the former are hairy, and ridged, dry as well as thin, and the peculiar median lines of _Poa_ are wanting. _Poa bulbosa_ has drier leaves than usual, but its leaves are devoid of ridges.

** _Ridges can be detected, but are slight and not distinct. Margins scabrid, at least at the base._

† _Leaves firm, flat, linear, acuminate, not narrowed below. Glabrous. Ligule membranous._

_Digraphis arundinacea_, Trin. (Reed-grass). Sheathed leaves round in section; blades convolute, tapering above, flat, firm, long and broad (1 in.) below. Mid-rib and veins numerous, and prominent below. Stoloniferous: branches extra-vaginal, often with deep red basal scales. Sheaths with much overlapping membranous margins, with a collar-like ledge above. Ligule long and somewhat acute. Wet ditches, &c., of no value (Figs. 7, 14).

For distinction between _Digraphis_ and _Dactylis_ see p. 41. _Poa pratensis_ is at once distinguished by its flattened shoots, more rounded leaf apex and shorter ligule. _Arundo Phragmites_ is easily distinguished by the ligule (see p. 51), and the other aquatic grasses are quite different (see p. 39).

_Phleum pratense_, L. (Timothy-grass). No stolons, but bulbous on dry ground. Early, and a heavy cropping hay grass: also excellent pasture; branches intra-vaginal, but burst the glabrous sheaths. Old sheaths fibrous. Leaves short, convolute, with scabrid margins owing to deflexed teeth: ridges obsolete above, no keel; broader and greyer green than _Alopecurus_. Ligule short on radical leaves, thin. Pastures. Perennial.

The smooth ligule, deflexed marginal teeth, and no keel distinguish it from _Arrhenatherum_.

_Phleum arenarium_, L. (Sand Phleum). Shoot annual, with no bulbs. Leaves broad, flat and glabrous, but rough at the edges, with descending teeth. Ridges low and flat. Sheaths smooth: leaves conduplicate. Ligule long. Sandy coasts, &c. A weed.

_Phleum asperum_, Jacq. and P. _Bœhmeri_, Schrad. are rare ruderal plants, and _P. alpinum_, L. is confined to the Scotch Highlands. _P. arenarium_ is sharply distinct by its conduplicate leaves and habitat.

_Alopecurus pratensis_ has narrower and less grey-green leaves than _Phleum pratense_, its ligule is shorter and blunter, its sheath more grooved and dark below, and the ridges more distinct and flat. It is relatively well rooted and is stoloniferous.

_Arrhenatherum avenaceum_, Beauv. (False Oat-grass). Loose tufts with short stolons, or bulbous below. Leaves few, narrow, thin, dry, rough, with very low flat ribs, convolute in bud, and practically glabrous. Sheath smooth. Ligule truncate, hairy on its outer surface. Bitter, and commonly undervalued by agriculturists, but useful in mixed pasture, and yields bulky, coarse hay.

There are often a few sparse isolated hairs on the low ribs. The base enters the sheath with slight and sometimes pinkish ledges. Ridges hardly observable. Traces of roughness if rubbed downwards. White lines, about 5 each side on holding up to the light. The not very long leaves taper slightly below.

_Arrhenatherum_ is liable to confusion with _Holcus_, _Anthoxanthum_, _Molinia_ and _Avena_, but it is typically glabrous, whereas the others are hairy.

From _Holcus_ it is easily distinguished by the sheaths, ligule and soft hairs of that genus.

_Anthoxanthum_ differs in its habit, ears, scent, sheath and ligule.

_Molinia_ differs in habit, ligule, sheath, and tough stringy roots, and the shape of the leaves.

_Avena pratensis_ differs in its narrow leaves, less prominent ridges, and ligule; _A. flavescens_ in its much broader and coarser hairy leaves, and the ligule; and _A. pubescens_ in pubescence and flat-shoots and ligule.

†† _Leaves very thin, blade tapering below. Keel prominent, but no ridges above. Ligule long and torn._

_Milium effusum_, L. (Spreading Millet-grass). Tufted perennial. Leaves linear-lanceolate, scabrid above. Sheath smooth. Bitter tasting. May be slightly hairy. Woods. It is much liked by birds, but is of no value in agriculture.

+B. Leaves or sheaths, or both, distinctly hairy.+

(α) Leaf-blades eared at the base.

(_a_) Ears sharply pointed. Leaves convolute, and sections of shoots round. Ligule short and inconspicuous.

_Agropyrum repens_, Beauv. (Couch-grass). A troublesome weed of arable land and gardens, &c., owing to the extraordinary vitality of its underground stolons. The young shoots are readily eaten by stock. Perennial, and extensively stoloniferous; bright or glaucous green. Blade thin, dry, rough edged, hairy and rough above, glabrous or hairy below. The short ligule fringed. Ears long, or sometimes short, pointed; often obliquely crossing in front of the sheath. Ridges inconspicuous. Hairs may be absent from the sheath, and nearly so from the blade.

The sea-shore varieties are stiffer and more glaucous, the leaves more ribbed, involute and pointed--e.g. _A. junceum_, Beauv.

_Agropyrum caninum_, Beauv. (Bearded Wheat-grass). Tufted weed, not creeping, in woods, &c. Blade thinner and rougher beneath, but very variable. Properties similar to those of _A. repens._

_Agropyrum_ may be confused with _Lolium_ (see p. 49) and _Agrostis_ (see p. 51), but hardly with any other grass, and with these only because it is liable to be glabrous or nearly so on poor soil.

_Elymus_ has much more pronounced ridges than the sea-shore varieties of _Agropyrum_.

(_b_) Base of blade with inconspicuous rounded ears. Leaves convolute. Ligule conspicuous.

_Anthoxanthum odoratum_, L. (Sweet Vernal-grass). Compact tuft. Common in pastures and hay, but it only forms a small proportion of the crop. One of the earliest grasses, and the principal one, which gives the scent to new-mown hay: a perfume has been extracted from it. Its value as fodder is probably overrated. Bitter tasted. Leaves more or less hairy at margins, especially at throat of sheath, flat, and slightly ridged. Sheath furrowed, often pubescent. Ligule long and blunt, with ciliate margins. Sweet scented when dried. The most shallow rooted of all meadow-grasses. Leaves often short and few.

_Anthoxanthum_ is sometimes confused with _Arrhenatherum_ (see p. 56) and _Molinia_; the latter differs in its ligule--a tuft of hair--its stringy roots, tapering leaf-base, less obvious ridges, and smooth sheaths, &c.

_Anthoxanthum_ is deep green and often very luxurious in rich wet soils--e.g. in Devonshire.

(_c_) Ears as mere collar-like ledges where the blade joins the sheath. Sheath usually pubescent or hispid with reflexed hairs. Ridges inconspicuous. Ligule very short.

✲ _Perennial, with firmer leaves_.

_Hordeum sylvaticum_, Huds. (Wood Barley). Leaves flat, thin but firm, rather broad, scaberulous. Sheath hispid, with reflexed hairs. Blade not tapering below. Translucent spaces between the veins as broad as the latter. Ligule short and blunt. Shady places. Useless.

_Hordeum pratense_, Huds. (Meadow Barley). Tufted, or bulbous below. Leaves narrower, flat, tending to roll up, scabrid above and hairy beneath. Sheath narrow, hairy. Moist meadows, and of some use as pasture in the young state.

✲✲ _Annual, with thin dry leaves_.

_Hordeum murinum_, L. (Wall Barley). Coarse tufts; leaves small, narrow, hairy or scabrid. Sheaths sparsely hispid, or very downy, inflated. Roads, &c. A useless weed.

_H. maritimum_, With. is a sea-side form, smaller and more glaucous. Sheaths hairy.

(β) Leaf-blades not eared at the base.

* Sheaths of radical leaves veined with red-purple.

_Holcus lanatus_, L. (Yorkshire Fog). A useless weed, but very common in pasture and hay; forming tussocks, greyish-green, softly hairy (tomentose). Blades with roundish ridges. Ligule short and obtuse. Sheath somewhat keeled, with trace of collar ledge. It is said to have a bitter taste (Fig. 15).

Ligule pilose. Tufted hairs along the broad rounded ridges, and on the lower surface and prominent keel.

The much rarer _H. mollis_, L. is not so long-haired, except on the nodes, and is more creeping and slender in habit. It is a “twitch.”

The Hordeums present several points of difficulty to beginners. The differences between the species are given above. _H. maritimum_ has narrower and thicker leaves than the rest.

Bromes are most likely to be confounded with Hordeums, but they have entire sheaths and no ears (see p. 43).

For distinctions between _H. murinum_ and _Lolium_ see p. 49. _H. sylvaticum_ and _Bromus asper_ (p. 44).

** No conspicuously red-veined sheaths.

† Ligule absent, or a tuft of hairs.

_Molinia cærulea_, Mœnch. (Purple Molinia). Tussocks, with tough stringy roots. Leaves narrowed below, and tapering above to a long point, ridges obsolete; very thin and dry but fairly stiff, and hairy above, especially at the base. Ligule absent, or a tuft of hairs. Sheaths smooth. Moors. Useless as forage, but used locally for brooms.

_Molinia_ is not easily confounded with any others but _Anthoxanthum_ (see p. 57), _Arrhenatherum_ (see p. 56) or _Brachypodium_.

_Brachypodium sylvaticum_ is distinguished by habitat, its broad leaves, membranous ligule, fibrous roots, &c.

_Kœleria cristata_, Pers. (Crested Kœleria). Very short, perennial in dry pastures, pubescent, pale green. Leaves narrow, tapering below, soon involute, ciliated. Ridges prominent, alternately high and low. Ligule obsolete, or a mere jagged yellowish line. Useless.

_Triodia decumbens_, Beauv. (Decumbent Heath-grass). Low perennial. Leaves narrow, obtuse, slightly ridged, tough, at length involute, with long, soft hairs, especially below and on the edges. Sheath grooved, hairy, especially at the throat. Ligule a tuft of hairs. Section of shoot flat; leaves conduplicate. Of no known use as fodder.

The rare grasses _Panicum glabrum_, Gaud., _P. viride_, _L._ and _P. Crus-galli_, L. introduced in the S.E. counties also come here.

†† _Ligule membranous._

_Avena flavescens_, L. (Yellow Oat-grass). Loose tufted perennial, pale green, with rounded shoots bursting the sheaths. Leaves flat, slender, soft, fine-ribbed and hairy, especially on the low ridges above. Sheath hairy, especially below, not keeled. Ligule short, obtuse, often truncate, ciliate. A valuable pasture and meadow-grass, also in water-meadows. Its roots are abundant, and it will grow well in calcareous soils (see Fig. 10).

_Avena pubescens_, Huds. (Downy Oat-grass). A variety of _A. pratensis_ (see p. 47), but less densely tufted, and the leaves flat and pubescent, and especially the sheaths very pubescent. Ligule ovate-acute. Shoots flat. Dry districts, and a weed.

_Avena flavescens_ is not easily confounded with any other grass if well grown. All the Poas otherwise like it are glabrous, and without the ridges. The same applies to _A. pubescens_.

_Arrhenatherum_ is also glabrous, its leaves narrower, its ridges much flatter and broader, and its ligule is hairy outside (see p. 56).

_Brachypodium sylvaticum_, Beauv. (Wood False-brome). Rather slender, perennial. Leaves flat and devoid of ridges; long, very thin and dry, limp, slightly tapering below, hirsute. Sheath round, hairy. Ligule fairly long, obtuse, toothed. Copses, &c. Useless.

_Brachypodium pinnatum_, L. (Heath False-brome), is a species growing in the open, with narrow, firm, rigid, erect leaves, hardly hairy; with distinct ridges, and tending to roll up. Ligule fringed with hair. Open heaths. Useless.

The only grasses likely to be confounded here are the Bromes, and they have entire sheaths.