CHAPTER I.

THE VEGETATIVE ORGANS.

That grasses are interesting and important plants is a fact recognised by botanists all the world over, yet it would appear that people in general can hardly have appreciated either their interest or their importance seeing how few popular works have been published concerning their structure and properties.

Apart from their almost universal distribution, and quite apart from the fascinating interest attaching to those extraordinary tropical giants, the Bamboos, West Indian Sugar-cane, the huge Reed-grasses of Africa, the Pampas-grasses of South America; and from the utilitarian value of the cereals--Maize, Rice, Wheat and other corn, &c.--everyone must be struck by the significance of the enormous tracts of land covered by grasses in all parts of the world, the Prairies of North America and the Savannahs of the South, the Steppes of Russia and Siberia, and the extensive tracts of meadow and pasture-land in Europe being but a few examples.

Although in the actual number of species the Grass family is by no means the largest in the vegetable kingdom, for there are far more Composites or Orchids, the curious sign of success in the struggle for existence comes out in grasses in that the number of _individuals_ far transcends those of any other group, and that they have taken possession of all parts of the earth’s surface. Some species are cosmopolitan--e.g. our common Reed, _Arundo Phragmites_; while others--e.g. several of our native species of _Festuca_ and _Poa_--are equally common in both hemispheres. On the whole the Tropics afford most species and fewest individuals, and the temperate regions most individuals.

Considering their multifarious uses as fodder and food, for brewing, weaving, building and a thousand other purposes, it is perhaps not too much to say that if every other species of plant were displaced by grasses of all kinds--as many indeed gradually are--man would still be able to supply his chief needs from them.

The profound significance of the grass-carpet of the earth, however, comes out most clearly when we realise the enormous amounts of energy daily stored up in the countless myriads of green blades as they fix their carbon. By decomposing the carbon-dioxide of the air in their chlorophyll apparatus by the action of the radiant energy of the sun, they build up starches and sugars and other plant-substances, which are then consumed and turned into flesh by our cattle and sheep and other herbivorous animals, and so furnish us with food. The whole theory of agriculture turns on this pivot, and the by no means small modicum of truth in such sayings as “All flesh is grass,” and that the man who can make two blades of grass grow where one grew before deserves well of his country, obtains a larger significance when it is realised that the only real gain of wealth is that represented by the storage of energy from without which comes to us by the action of green leaves waving in the sunshine.

The true Grasses, comprising the Natural Order Graminaceæ--also written Gramineæ--are often popularly confounded with other herbs which possess narrow green ribbon-like leaves, or even with plants of very different aspects--e.g. Cotton-grass (_Eriophorum_) and other Sedges, and the names Rib-grass (_Plantago_), Knot-grass (_Polygonum_), Scorpion-grass (_Myosotis_) and Sea-grass (_Zostera_), as well as the general usage of the word grass to signify all kinds of leguminous and other hay-plants in agriculture, point to the wider use of the word in former times. This has been explained by the use of the words _gaers_, _gres_, _gyrs_, and grass in the old herbals to indicate any kind of small herbage.

In view of the importance of our British grasses in agriculture, I have here put together some results of observation and reading in the hope that they may aid students in recognising easily our ordinary agricultural and wild grasses. During several years of work in the fields, principally directed at first to the study of the parasitic fungi on grasses, and subsequently to that of the importance of grasses in forestry and agriculture, and to the variations they exhibit, the need of some guide to the identification of a grass at any time of the year, whether in flower or not, forced itself on the attention, and although a botanist naturally turns to a good Flora when he has the grass in flower, as the best and quickest way of ascertaining the species, it soon became evident that much may be done by the study of the leaves and vegetative parts of most grasses. Indeed some are recognisable at a glance by certain characters well known to continental observers: in the case of others the matter is more difficult, and perhaps with a few it is impossible to be certain of the species from such characters only.

Nevertheless, while the best means for the determination of species are always in the floral characters so well worked up in the Floras of Hooker, Bentham and others, there is unquestionably much value in the characters of the vegetative organs also, as the works of Jessen, Lund, Stebler, Vesque and others abroad, and Sinclair, Parnell, Sowerby and others in this country attest.

Almost the only plants confounded with true grasses by the ordinary observer are the sedges and a few rushes. Apart from the very different floral structures, there are two or three easily discoverable marks for distinguishing all our grasses from other plants (Fig. 1). The first is their leaves are arranged in _two rows_, alternately, up the stems; and the second that their stems are circular or flattened in section, or if of some other shape they are _never triangular_ and _solid_[1] (Figs. 6 and 7). Moreover the leaves are always of some elongated shape, and without leaf-stalks[2], but pass below into a _sheath_, which runs some way down the stem and is nearly always perceptibly split (Figs. 8-13). Further, the stems themselves are usually terete, and distinctly hollow except at the swollen nodes, and only branch low down at the surface of the ground or below it[3].

All our native grasses are herbaceous, and none of them attain very large dimensions. In the following lists I term those small which average about 6-18 inches in the height of the tufts, whereas those over 3 feet high may be termed large, the tufts being regarded as in flower. The sizes cannot be given very accurately, and starved specimens are frequently found dwarfed, but in most cases these averages are not far wrong for the species freely growing as ordinarily met with, and in some cases are useful. I have omitted the rare species throughout, and in the annexed lists have added the popular names.

LARGE GRASSES.

(Over 3 feet.)

_Milium effusum_ (Millet-grass). _Digraphis arundinacea_ (Reed-grass). _Aira cæspitosa_ (Tufted Hair-grass). _Arrhenatherum avenaceum_ (False Oat). _Elymus arenarius_ (Lyme-grass). _Bromus asper_ (Hairy Brome). _B. giganteus_ (Tall Brome). _Festuca elatior_ (Meadow Fescue). _F. sylvatica_ (Reed Fescue). _Glyceria aquatica_ (Reed Sweet-grass). _G. fluitans_ (Floating Sweet-grass). _Arundo Phragmites_ (Common Reed).

MEDIUM GRASSES.

(1-3 feet.)

_Phleum pratense_ (Timothy). _Avena pratensis_ (Perennial Oat-grass). _Anthoxanthum odoratum_ (Sweet Vernal). _Alopecurus agrestis_ (Slender Foxtail). _A. pratensis_ (Meadow Foxtail). _Agrostis alba_ (Fiorin). _Psamma arenaria_ (Sea Mat-grass). _Avena flavescens_ (Yellow Oat-grass). _Holcus lanatus_ (Yorkshire Fog). _Hordeum sylvaticum_ (Wood Barley). _H. pratense_ (Meadow Barley). _Agropyrum repens_ (Couch-grass). _A. caninum_ (Fibrous Twitch). _Lolium italicum_ (Italian Rye-grass). _Brachypodium sylvaticum_ (Wood False-Brome). _B. pinnatum_ (Heath False-Brome). _Bromus erectus_ (Upright Brome). _B. sterilis_ (Barren Brome). _B. arvensis_ (Field Brome). _Festuca ovina_ (var. _rubra_, &c.). (Sheep’s Fescue). _F. elatior_ (var. _pratensis_). (Meadow Fescue.) _Dactylis glomerata_ (Cock’s-foot). _Cynosurus cristatus_ (Crested Dog’s-tail). _Poa pratensis_ (Meadow-grass). _P. trivialis_ (Rough stalked Meadow-grass). _P. nemoralis_ (Wood Poa). _Molinia cærulea_ (Flying Bent). _Melica nutans_ (Mountain Melick). _M. uniflora_ (Wood Melick).

SMALL GRASSES.

(6-18 inches.)

_Phleum arenarium_ (Sand Cat’s-tail). _Alopecurus geniculatus_ (Marsh Foxtail). _Agrostis canina_ (Brown Bent). _Aira flexuosa_ (Wavy Hair-grass). _Aira canescens_ (Grey Hair-grass). _A. præcox_ (Early Hair-grass). _A. caryophyllea_ (Silvery Hair-grass). _Nardus stricta_ (Moor Mat-grass). _Hordeum murinum_ (Wall Barley). _H. maritimum_ (Sea Barley). _Lolium perenne_ (Rye-grass). _L. temulentum_ (Darnel). _Bromus arvensis_ (var. _mollis_). (Field Brome). _Festuca ovina_ (Sheep’s Fescue). _F. Myuros_ (Rat’s-tail Fescue). _Briza media_ (Quaking-grass). _Poa maritima_ (Sea Poa). _P. annua_ (Annual Meadow-grass). _P. compressa_ (Flattened Meadow-grass). _P. alpina_ (Alpine Poa). _P. bulbosa_ (Bulbous Poa). _Triodia decumbens_ (Heath-grass). _Kœleria cristata_ (Crested Kœleria).

The roots of our grasses are almost always thin and _fibrous_ and are adventitious from the nodes, frequently forming radiating crowns round the base and easily pulled up, and usually broken in the process; but in the case of a few moor grasses--especially _Nardus_ (Fig. 2) and _Molinia_--the roots are so tough and thick (_stringy_) as to resist breakage very efficiently. In stoloniferous grasses a similar difficulty of removal may be caused in a slighter degree by the underground stems. In a few cases, e.g. _Alopecurus bulbosus_ (Fig. 3), _Poa bulbosa_, _Phleum pratense_ and _P. Bœhmeri_, _Arrhenatherum avenaceum_, and to a slighter extent in _Poa alpina_ and one or two others, the lowermost internodes and sheaths of the stems may be swollen and stored with food-materials, and a sort of _tuber_ or _bulb_ results; this is especially apt to occur in dry sandy soils. In old lawns, pastures, &c., the roots of _Poa annua_ and others may have nodules on them due to the presence of certain small Nematode worms, _Heterodera_.

Grasses are annual, biennial, or perennial, and it is often of importance to know which. The point may usually be determined by examining the shoots. If all the shoots have flowering stems in them, and are evidently of the current year, the grass is an annual; but if any shoots have leaves only, it is either biennial or perennial: to determine which is not always easy, but in perennial grasses there will generally be evident remains of older leaf-bases and shoots, and if there are distinct underground stolons or creeping rhizomes as well the point may be considered decided, and the grass is perennial, as is the case with most of our important species. If all the shoots are barren, the grass is a biennial in its first year of growth: if all have flowering stems in them, but show traces of old leaf-bases of the previous year, then the grass is a biennial in its second year. The proof of biennial character is not always easy, however, and a few grasses may be either annual or biennial, or biennial or perennial, according to conditions--e.g. species of _Hordeum_, _Bromus_, &c. In the following lists I have given the duration of the principal grasses, where the character is especially important.

ANNUALS.

_Phleum arenarium._ _Aira præcox._ _A. caryophyllea._ _Hordeum murinum._ _H. maritimum._ _Lolium temulentum._ _Festuca Myurus._ _Briza minor._ _Poa rigida._ _P. annua._

ANNUALS

which may become biennial or perennial.

_Alopecurus geniculatus._ _Hordeum pratense._ _Lolium perenne._ _L. italicum_ (may be perennial). _Bromus asper_ (may be perennial). _B. sterilis._ _B. arvensis_ (may be perennial).

PERENNIALS.

_Holcus lanatus._ _H. mollis._ _Nardus._ _Hordeum sylvaticum._ _Agropyrum._ _Brachypodium._ _Bromus erectus._ _B. giganteus._ _Festuca ovina._ _F. elatior._ _F. sylvatica._ _Dactylis._ _Cynosurus cristatus._ _Briza media._ _Milium._ _Anthoxanthum._ _Digraphis._ _Phleum pratense._ _Alopecurus pratensis._ _Agrostis alba._ _A. canina._ _Psamma._ _Aira cæspitosa._ _A. flexuosa._ _A. canescens._ _Avena pratensis._ _A. flavescens._ _Arrhenatherum._ _Glyceria aquatica._ _G. fluitans._ _Poa maritima._ _P. compressa._ _P. pratensis._ _P. trivialis._ _P. nemoralis._ _P. alpina._ _P. bulbosa._ _Molinia._ _Melica._ _Triodia._ _Kœleria._ _Arundo._

The rhizome of a perennial grass is continued sympodially by means of buds branching from the lowermost joints of the flowering shoots, and some importance is attached to the mode of spreading of these lateral sprouting shoots. The buds always arise in the axils of the lower leaf-sheaths--i.e. they are _intra-vaginal_. If they remain intra-vaginal during further growth, the shoots are forced upwards and only _tufts_ (Fig. 2) are formed, except in so far as such shoots may fall prostrate on the surface of the ground later, and throw out roots from their nodes, and so act as _runners_ or offsets, or put out a few roots &c. as they ascend through the soil. But in many cases the buds soon burst through the leaf-sheaths, and develope as _extra-vaginal_ shoots, and may then run horizontally as underground _stolons_. Only creeping grasses of these latter kinds can rapidly cover large areas[4]: the grasses with intra-vaginal shoots only can only make tufts or “tussocks.” Several peculiarities in the habits of grasses depend on these facts. The following are the most important creeping, or _stoloniferous_ species, contrasted with the much more common _tufted_ and the far rarer grasses with _runners_ above ground (Fig. 4). Some of these (_Elymus_, _Psamma_, &c.) are of great importance as sand-binders.—

With intra-vaginal branches only.

_Lolium_--slightly stoloniferous. _Festuca elatior_--slightly stoloniferous. _Avena flavescens_--slightly stoloniferous. _Phleum pratense_--no stolons, but may be bulbous. _Dactylis_--no stolons. _Festuca ovina_--no stolons. _Poa alpina_--no stolons. _Cynosurus_--no stolons.

With extra-vaginal shoots.

_Arrhenatherum_--short stolons, sometimes bulbous. _Holcus lanatus_--creeping. _Alopecurus pratensis_--long stolons. _Anthoxanthum_--slightly stoloniferous. _Agrostis alba_ (var. _stolonifera_)--long stolons and runners. _Digraphis_--long stolons. _Poa pratensis_--long stolons. _P. trivialis_--runners only. _Festuca heterophylla_, Lam.--a variety of _F. ovina_ with slight stolons. _F. rubra_ (Linn.)--a variety of _F. ovina_ with long stolons. _Bromus erectus_--no stolons. _B. inermis_--long stolons.

Creeping below ground and truly stoloniferous.

_Agropyrum._ _Elymus._ _Psamma._ _Poa pratensis._ _P. compressa._ _Agrostis alba_ (var. _stolonifera_). _Alopecurus pratensis._ _Brachypodium_ (slightly). _Bromus erectus_ (slightly). _Festuca ovina_ (var. _rubra_, Linn.). _F. elatior_ (slightly). _Briza_ (slightly). _Glyceria._ _Poa maritima._ _Melica._ _Arundo._

Tufted Grasses.

_Milium._ _Agrostis alba_ (on downs, &c.). _Aira cæspitosa._ _A. flexuosa._ _A. canescens._ _A. præcox._ _A. caryophyllea._ _Avena pratensis_ (slightly creeping). _Arrhenatherum._ _Nardus_ (Fig. 2). _Hordeum sylvaticum._ _Lolium._ _Bromus._ _Festuca ovina_ (except some varieties). _F. sylvatica._ _F. Myurus._ _Dactylis._ _Cynosurus._ _Poa rigida._ _P. annua._ _P. trivialis._ _P. nemoralis._ _P. alpina._ _P. bulbosa._ _Molinia._ _Triodia._ _Kœleria._

Creeping above ground (with runners).

_Holcus lanatus._ _Alopecurus geniculatus._ _Agrostis alba_ (var. _stolonifera_). _Hordeum pratense_ (slightly). _H. murinum_ (slightly). _Catabrosa_ (Fig. 4). _Cynodon_ (Fig. 5).

Hackel has pointed out that a distinction must be drawn between the true nodes of the _culm_, and the swellings often found at the base of the _sheaths_ themselves over these: the latter are often conspicuous when the former are inconspicuous--e.g. most species of _Agrostis_, _Avena_, _Festuca_, &c.

The nodes are of importance in the description of a few species only--e.g. they are usually dark coloured in certain _Poas_ such as _P. compressa_ and _P. nemoralis_; they are sharply bent in _Alopecurus geniculatus_, and may be so in other species if “layed” by wind, rank growth, &c.

A point of considerable classificatory value is the shape of the transverse section of the shoot, which is correlated with the mode of folding up of the young leaf-blades.

In most grasses the blades are _convolute_--i.e. rolled up like the paper of a cigarette, one edge over the other--and the section of the shoot is round (Fig. 7). In some cases, however, the leaves are _conduplicate_--i.e. each half of the lamina is folded flat on the other, the upper sides being turned face to face inwards, with the mid-rib as the hinge--and in this case the shoots are more or less compressed (Fig. 6).

In these latter cases the transverse section may be elliptical--e.g. _Poa pratensis_ and _P. alpina_, _Briza_, &c., or more flattened and linear-oblong--e.g. _Glyceria fluitans_--with the flattened sides straight, or the section is oval but pointed more or less at each end owing to projecting keels and leaf-edges, and the form is _naviculate_--e.g. _Glyceria aquatica_, _Dactylis_ (Fig. 6)--or, the sides being less flattened, more or less _rhomboidal_ as in _Poa trivialis_. In _Melica_ the leaves are convolute and the shoot-section _quadrangular_.

Flat, and usually sharp-edged shoots.

_Dactylis glomerata_ (Fig. 6). _Poa trivialis_, _P. annua_, _P. pratensis_, _P. compressa_, _P. maritima_, and _P. alpina_. _Glyceria aquatica_ and _G. fluitans_. _Avena pubescens._ _Lolium perenne._