CAMBRIDGE BIOLOGICAL SERIES.
GENERAL EDITOR:--ARTHUR E. SHIPLEY, M.A., F.R.S.
FELLOW AND TUTOR OF CHRIST’s COLLEGE, CAMBRIDGE.
GRASSES.
CAMBRIDGE UNIVERSITY PRESS WAREHOUSE,
C. F. CLAY, MANAGER.
London: FETTER LANE, E.C.
Edinburgh: 100, PRINCES STREET.
[Illustration]
ALSO
London: H. K. LEWIS, 136, GOWER STREET, W.C.
Leipzig: F. A. BROCKHAUS.
New York: G. P. PUTNAM’S SONS.
Bombay and Calcutta: MACMILLAN & CO. LTD.
[_All Rights reserved._]
GRASSES
A HANDBOOK FOR USE IN THE FIELD
AND LABORATORY.
BY
H. MARSHALL WARD, SC.D., F.R.S.
LATE PROFESSOR OF BOTANY IN THE UNIVERSITY OF CAMBRIDGE.
CAMBRIDGE:
AT THE UNIVERSITY PRESS.
1908
_First Edition 1901 Reprinted 1908_
PREFACE.
The following pages have been written in the hope that they may be
used in the field and in the laboratory with specimens of our ordinary
grasses in the hand. Most of the exercises involved demand exact
study by means of a good hand-lens, a mode of investigation far too
much neglected in modern teaching. The book is not intended to be a
complete manual of grasses, but to be an account of our common native
species, so arranged that the student may learn how to closely observe
and deal with the distinctive characters of these remarkable plants
when such problems as the botanical analysis of a meadow or pasture,
of hay, of weeds, or of “seed” grasses are presented, as well as when
investigating questions of more abstract scientific nature.
I have not hesitated, however, to introduce general statements on the
biology and physiological peculiarities of grasses where such may serve
the purpose of interesting the reader in the wider botanical bearings
of the subject, though several reasons may be urged against extending
this part of the theme in a book intended to be portable, and of direct
practical use to students in the field.
I have pleasure in expressing my thanks to Mr R. H. Biffen for
carefully testing the classification of “seeds” on pp. 135-174, and to
him and to Mr Shipley for kindly looking over the proofs; also to Mr
Lewton-Brain, who has tested the classification of leaf-sections put
forward on pp. 72-82, and prepared the drawings for Figs. 21-28.
That errors are entirely absent from such a work as this is perhaps too
much to expect: I hope they are few, and that readers will oblige me
with any corrections they may find necessary or advantageous for the
better working of the tables.
The list of the chief authorities referred to, which students who
desire to proceed further with the study of grasses should consult, is
given at the end.
I have pleasure in acknowledging my indebtedness to the following
works for illustrations which are inserted by permission of the
several publishers:--Stebler’s _Forage Plants_ (published by Nutt &
Co.), Nobbe’s _Handbuch der Samenkunde_ (Wiegandt, Hempel and Parey,
Berlin), Harz’s _Landwirthschaftliche Samenkunde_ (Paul Parey, Berlin),
Strasburger and Noll’s _Text-Book of Botany_ (Macmillan & Co.),
Figuier’s _Vegetable World_ (Cassell & Co.), Lubbock’s _Flowers, Fruits
and Seeds_ (Macmillan & Co.), Kerner’s _Natural History of Plants_
(Blackie & Son), and Oliver’s _First Book of Indian Botany_ (Macmillan
& Co.).
It is impossible to avoid the question of variation in work of this
kind, and students will without doubt come across instances--especially
in such genera as _Agropyrum_, _Festuca_, _Agrostis_ and _Bromus_--of
small variations which show how impossible it is to fit the facts
of living organisms into the rigid frames of classification. It
may possibly be urged that this invalidates all attempts at such
classifications: the same argument applies to all our systems, though
it is perhaps less disastrous to the best Natural Systems which attempt
to take in large groups of facts, than to artificial systems selected
for special purposes. Perhaps something useful may be learned by
showing more clearly where and how grasses vary, and I hope that the
application to them of these preliminary tests may elucidate more facts
as we proceed.
H. M. W.
CAMBRIDGE, _April_, 1901.
CONTENTS.
CHAPTER I.
PAGE
THE VEGETATIVE ORGANS 1
CHAPTER II.
THE VEGETATIVE ORGANS (_continued_) 17
CHAPTER III.
GRASSES CLASSIFIED ACCORDING TO THEIR VEGETATIVE CHARACTERS 39
CHAPTER IV.
ANATOMY AND HISTOLOGY 62
CHAPTER V.
GRASSES CLASSIFIED ACCORDING TO THE ANATOMICAL CHARACTERS
OF THE LEAF 72
CHAPTER VI.
GRASSES IN FLOWER 83
CHAPTER VII.
GRASSES GROUPED ACCORDING TO THEIR FLOWERS AND
INFLORESCENCES 99
CHAPTER VIII.
THE FRUIT AND SEED 119
CHAPTER IX.
CLASSIFICATION OF GRASSES BY THE “SEEDS” (GRAINS) 135
BIBLIOGRAPHY 175
INDEX, GLOSSARY AND LIST OF SYNONYMS 177
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].
[Illustration: Fig. 1. A plant of Oat (_Avena_), an example of a
typical grass, showing tufted habit and loose paniculate inflorescence
(reduced). Figuier.]
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_.
[Illustration: Fig. 2. _Nardus stricta._ Plant showing tufted habit,
and simple spikate inflorescence, with pointed spikelets all turned
towards one side (secund) on the rachis (reduced). Note also the
bristle-like (setaceous) leaves at length reflexed. Parnell.]
[Illustration: Fig. 3. _Alopecurus geniculatus_, var. _bulbosus_. Plant
(reduced) showing habit, bulbous shoots and cylindrical spike-like
inflorescences (Foxtail type). Notice the inflated sheaths, and the
“kneed” lower parts of the ascending stems. Parnell.]
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._
[Illustration: Fig. 4. _Catabrosa aquatica._ Plant showing the creeping
habit, rooting nodes, and paniculate inflorescence (reduced). Parnell.]
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.
[Illustration: Fig. 5. _Cynodon Dactylon._ Plant (reduced) showing
creeping and stoloniferous habit, and peculiar inflorescence of
digitate spikes. Parnell.]
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).
[Illustration: Fig. 6. _Dactylis glomerata._ Transverse section of a
leaf-shoot (× 5). _A_, conduplicate leaf-blade. _B_, sheath. Stebler.]
[Illustration: Fig. 7. _Digraphis arundinacea._ Transverse section of a
leaf-shoot (× 5). _A_, sheath. _B_, convolute leaves. Compare Fig. 14.
Stebler.]
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._