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Title: A Handbook of Some South Indian Grasses

Author: Rai Bahadur K. Ranga Achariyar
        C. Tadulinga Mudaliyar

Release Date: December 28, 2007 [EBook #24063]

Language: English

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A HANDBOOK
OF
SOME SOUTH INDIAN GRASSES


BY
RAI BAHADUR K. RANGA ACHARIYAR, M.A., L.T.,
_Indian Agricultural Service, Agricultural College, Coimbatore, and
Fellow of the Madras University_


ASSISTED BY
C. TADULINGA MUDALIYAR, F.L.S.,
_Agricultural College, Coimbatore._


MADRAS:
PRINTED BY THE SUPERINTENDENT, GOVERNMENT PRESS.
1921

Price, 4 _rupees_ 8 _annas_




PREFACE


This book is intended to serve as a guide to the study of grasses of the
plains of South India. For the past few years I have been receiving
grasses for identification, almost every week, from the officers of the
Agricultural and Forest Departments and others interested in grasses.
The requirements of these men and the absence of a suitable book induced
me to write this book.

I have included in this book about one hundred grasses of wide
distribution in the plains of South India. Many of them occur also in
other parts of India. The rarer grasses of the plains and those growing
on the hills are omitted, with a view to deal with them separately.

The value of grasses can be realized from the fact that man can supply
all his needs from them alone, and their importance in agriculture is
very great, as the welfare of the cattle is dependent upon grasses.
Farmers, as a rule, take no interest in them, although profitable
agriculture is impossible without grasses. Very few of them can give the
names of at least half a dozen grasses growing on their land. They
neglect grasses, because they are common and are found everywhere. They
cannot discriminate between them. To a farmer "grass is grass" and that
is all he cares to trouble himself about. About grasses Robinson writes
"Grass is King. It rules and governs the world. It is the very
foundation of all commerce: without it the earth would be a barren
waste, and cotton, gold, and commerce all dead."

In the early days when the population was very much limited and when
land not brought under cultivation was extensive plenty of green grasses
was upon it and pastures were numerous. So the farmer paid no attention
to the grasses, and it did not matter much. But now, population has
increased, unoccupied land has decreased very much and the cattle have
increased in number. Consequently he has to pay more attention to
grasses.

On account of the scarcity of fodder, people interested in agriculture
and cattle rearing have very often imported foreign grasses and fodder
plants into this country, but so far no one has succeeded in
establishing any one of them on any large scale. Usually a great amount
of labour and much money is spent in these attempts. If the same amount
of attention is bestowed on indigenous grasses, better results can be
obtained with less labour and money. There are many indigenous grasses
that will yield plenty of stuff, if they are given a chance to grow. The
present deterioration of grasses is mainly due to overgrazing and
trampling by men and cattle.

To prove the beneficial effects which result from preventing overgrazing
and trampling, Mr. G. R. Hilson, Deputy Director of Agriculture (now
Cotton Expert), selected some portion of the waste land in the
neighbourhood of the Farm at Hagari and closed it for men and cattle. As
a result of this measure, in two years, a number of grasses and other
plants were found growing on the enclosed area very well, and all of
them seeded well. Of course the unenclosed areas were bare as usual.

In the preparation of this book I received considerable help from
M.R.Ry. C. Tadulinga Mudaliyar Avargal, F.L.S., Assistant Lecturing and
Systematic Botanist, in the description of species and I am indebted to
M.R.Ry. P.S. Jivanna Rao, M.A., Teaching Assistant, for assistance in
proofreading.

I have to express my deep obligation to Mr. G. A. D. Stuart, I.C.S.,
Director of Agriculture, for encouragement to undertake this work and to
the Madras Government for ordering its publication.

For the excellence in the get up of the book I am indebted to Mr. F. L.
Gilbert, Superintendent, Government Press.

K. RANGACHARI.

AGRICULTURAL COLLEGE,
LAWLEY ROAD, COIMBATORE,
_2nd June 1921._




CONTENTS

                                                                    PAGE
PREFACE                                                              iii
CHAPTER    I--Introduction                                             1
          II--The vegetative organs                                    5
         III--The inflorescence and flower                            13
          IV--Histology of the vegetative organs                      19
           V--Classification                                          43
          VI--Panicaceae                                               45
         VII--Oryzeae and Zoysieae                                     123
        VIII--Andropogoneae                                           138
          IX--Agrostideae and Chlorideae                               220
           X--Festucaceae and Hordeae                                  283
GLOSSARY                                                             311
INDEX                                                                315




A HANDBOOK OF SOME COMMON SOUTH
INDIAN GRASSES.




CHAPTER I.

INTRODUCTION.


Grasses occupy wide tracts of land and they are evenly distributed in
all parts of the world. They occur in every soil, in all kinds of
situations and under all climatic conditions. In certain places grasses
form a leading feature of the flora. As grasses do not like shade, they
are not usually abundant within the forests either as regards the number
of individuals, or of species. But in open places they do very well and
sometimes whole tracts become grass-lands. Then a very great portion of
the actual vegetation would consist of grasses.

On account of their almost universal distribution and their great
economic value grasses are of great importance to man. And yet very few
people appreciate the worth of grasses. Although several families of
plants supply the wants of man, the grass family exceeds all the others
in the amount and the value of its products. The grasses growing in
pasture land and the cereals grown all over the world are of more value
to man and his domestic animals than all the other plants taken
together.

To the popular mind grasses are only herbaceous plants with narrow
leaves such as the hariali, ginger grass and the kolakattai grass. But
in the grass family or Gramineae the cereals, sugarcane and bamboos are
also included.

Grasses are rather interesting in that they are usually successful in
occupying large tracts of land to the exclusion of other plants. If we
take into consideration the number of individuals of any species of
grass, they will be found to out-number those of any species of any
other family. Even as regards the number of species this family ranks
fifth, the first four places being occupied respectively by Compositae,
Leguminosae, Orchideae and Rubiaceae.

As grasses form an exceedingly natural family it is very difficult for
beginners to readily distinguish them from one another.

The leaves and branches of grasses are very much alike and the flowers
are so small that they are liable to be passed by unnoticed. The
recognition of even our common grasses is quite a task for a botanist.

To understand the general structure of grasses and to become familiar
with them it is necessary to study closely some common grasses. We shall
begin our study by selecting as a type one of the species of the genus
Panicum.

_Panicum javanicum_ is an annual herb with stems radiating in all
directions from a centre. The plant is fixed to the soil by a tuft of
fibrous roots all springing from the bases of the stems. In addition to
this crown of fibrous roots, there may be roots at the nodes of some of
the prostrate branches. The stems and branches are short at first, and
leaves arise on them one after the other in rapid succession. After the
appearance of a fair number of leaves the stem elongates gradually and
it finally ends in an inflorescence.

[Illustration: Fig. 1.--Panicum javanicum. (Full plant.)]

The stem consists of =nodes= and =internodes=. The internodes are
cylindrical and somewhat flattened on the side towards the axillary bud.
When young they are completely covered by the leaves and the older ones
have only their lower portions covered by the leaf-sheaths. Usually they
complete their growth in length very soon, but the lower portion of the
internode, just above the node and enclosed by the sheath, retains its
power of growth for some time.

The leaf consists of the two parts, the =leaf-sheath= and the
=leaf-blade=. At the junction of these two parts there is a very thin
narrow membrane with fine hairs on its free margin. This is called the
=ligule=. (See fig. 2.)

The leaf-sheath is attached at its base to the node and it is slightly
swollen just above the place of insertion. It covers the internode, one
margin being inside and the other outside. The surface of the sheath is
sparsely covered with long hairs springing from small tubercles. The
outer margin of the sheath bears fine hairs all along its length. (See
fig. 2.)

The leaf-blade is broadly lanceolate, with a tip finely drawn out. Its
base is rounded and the margin wavy, especially so towards the base. On
the margin towards the base long hairs are seen, and some of these arise
from small tubercles. The margin has a hyaline border which is very
minutely serrate. There is a distinct midrib and, on holding the leaf
against the light, four or five small veins come in to view. In the
spaces between these veins lie many fine veins. All the veins run
parallel from the base to the apex. At the base of the blade the veins
get into the leaf-sheath and therefore the sheath becomes striated. Just
above the ligule and at the base of the leaf-blade there is a colourless
narrow zone. This is called the =collar=.

[Illustration: Fig. 2.--Leaf of Panicum javanicum.

A. Full leaf; B. a portion of the leaf showing 1. the ligule and 2. the
collar.]

As already stated the inflorescences appear at the free ends of
branches. Every branch sooner or later terminates in an inflorescence
which is a compound raceme. There are usually five or six racemes in the
inflorescence. Each raceme has an axis, called the =rachis=, which bears
unilaterally two rows of bud-like bodies. These bud-like bodies are the
units of the inflorescence and they are called =spikelets=. (See fig.
3.)

[Illustration: Fig. 3.--The inflorescence of Panicum javanicum.

1. Inflorescence; 2 and 3. the front and the back view of a raceme.]

The spikelets are softly hairy and are shortly stalked. The pedicels of
spikelets are hairy and sometimes one or two long hairs are also found
on them. Each of these spikelets consists of four green membranous
structures called =glumes=. The first two glumes are unequal, the first
being very small. The second and the third glumes are broadly
ovate-oblong with acute tips. Both are of the same height and texture,
but the second is 7-nerved and the third 5-nerved. The fourth glume is
membranous when young, but later on it becomes thick, coriaceous and
rugose at the surface. Just opposite to the fourth glume there is a flat
structure with two nerves, similar to the glume in texture. This is
called the =palea=. The fourth glume and its palea adhere together by
their margins. Inside the fourth glume and between it and the palea
there are three stamens and an ovary with two styles ending in feathery
stigmas. Just in front of the ovary and outside the stamens two very
small scale-like bodies are found. These are the =lodicules=. They are
fleshy and well developed in flowers that are about to open. In the
spikelet there is only one full flower. The third glume contains no
flower in it, but occasionally there may be in its axil three stamens.
The first two glumes are always empty and so they are called empty
glumes. (See fig. 4.) In mature spikelets the grain which is free is
enclosed by the fourth glume and its palea.

[Illustration: Fig. 4.--Parts of the spikelets of Panicum javanicum.

A. A spikelet; 1, 2, 3 and 4. the first, second, third and the fourth
glume, respectively; 3a. palea of the third glume; 4a. palea of the
fourth glume; 5. lodicules; 6. stamens; 7. ovary; 8. stigmas.]




CHAPTER II.

THE VEGETATIVE ORGANS.


Grasses vary very much in their habit. Some grasses grow erect forming
tufts and others form cushions with the branches creeping along the
ground. (See figs. 5 and 6.) We usually find all intermediate stages
from the erect to the prostrate habit. Underground stems such as stolons
and rhizomes occur in some grasses. Grasses of one particular species
generally retain the same habit but this does not always hold good. For
example _Tragus racemosus_ grows with all its branches quite prostrate
in a poor, dry, open soil. If, on the other hand, this happens to grow
in rich soils, or amidst other plants or grasses, it assumes an erect,
somewhat tufted habit. _Andropogon contortus_ and _Andropogon pertusus_
are other grasses with a tendency for variation in habit. Plants that
are usually small often attain large dimensions under favourable
conditions of growth. Ordinarily the grass _Panicum javanicum_ grows
only to 1 or 2 feet. (See fig. 1.) The same plant in a good rich soil
grew to about 6 feet in four months. (See fig. 7.)

[Illustration: Fig. 5.--Eleusine aegyptiaca.]

Some grasses are annual while others are perennial. It is often
difficult to determine whether a certain grass is annual or perennial.
But by examining the shoot-system this can be ascertained easily. In an
annual all the stems and branches usually end in inflorescences and they
will all be of the same year. If, on the other hand, both young leafy
branches and old branches ending in inflorescences are found mixed, it
must be a perennial grass. The presence of the remains of old leaves,
underground stolons and rhizomes is also evidence showing the perennial
character of the plant.

Grasses are eminently adapted to occupy completely large areas of land.
They are also capable of very rapid extension over large areas, on
account of the production of stolons, rhizomes and the formation of
adventitious roots.

=The root-system.=--The root-system of grasses is very striking in its
character. In most grasses, especially in erect ones, several roots all
of about the same diameter arise in a dense tuft from nearly the same
level and from the lower-most nodes of the stems. The roots are all thin
and fibrous in the vast majority of these plants, and they are tough and
wiry only in a few cases such as in the case of the roots of _Pennisetum
cenchroides_, _P. Alopecuros_, _Ischaemum pilosum_ and _Andropogon
Schoenanthus_.

On a close examination it will become evident that all the roots of a
grass plant are adventitious. Inasmuch as the growth of the primary root
is soon overtaken by other roots growing from the stem, all the roots
happen to be of the same size. Roots arise from the nodes just above the
insertion of the leaf, and they grow piercing the leaf-sheath.

[Illustration: Fig. 6.--Panicum Crus-galli.]

Grasses in which stolons and prostrate branches occur have, in addition
to the usual radiating crown of roots at the base, aerial roots growing
out of the upper nodes of the branches and fixing them to the soil. Such
roots become supporting or prop roots and are particularly conspicuous
in several stout tall grasses such as _Andropogon Sorghum_, _Zea Mays_
and _Pennisetum typhoideum_. (See figs. 8 and 9.)

All the roots bear branch-roots which originate from the inner portion
of the mother roots in the usual manner. The character and the extent of
the development of the root-system is to a large extent dependent upon
the nature of the soil and its moisture content. In light dry soils
roots remain generally stunted and in well drained rich soils they
attain their maximum development. In clayey soils roots penetrate only
to short distances. When the soil is rich and sandy roots go deeper and
extend in all directions. The root-systems of most grasses are
superficial and so are best adapted for surface-feeding.

[Illustration: Fig. 7.--Panicum javanicum.]

=The shoot-system.=--The shoot-system varies with the duration of the
life of the plant. In annual grasses stems are in most cases erect and
even if they are not entirely so they become erect at the time of
flowering. They are attached to the soil by a tuft of fibrous roots
arising from the base of the stems. But in perennials in addition to
erect branches, creeping branches, stolons and rhizomes may occur.

[Illustration: Fig. 8.--Prop roots of Andropogon Sorghum.]

[Illustration: Fig. 9.--Aerial roots of Ischaemum ciliare.]

The stem is either cylindrical or compressed and consists of nodes and
internodes. In most grasses the internodes are usually hollow, the
cavity being lined by the remains of the original pith cells. However,
there are also grasses in which the stems remain solid throughout. In
many grasses the basal portions of stems are more leafy and the
internodes are short, but in the upper portions the internodes become
longer separating the leaves one from the other.

In young shoots the leaves grow much faster than the internodes and
consequently internodes remain small, and leaves become very
conspicuous. The youngest portions of the shoots are by this means
always well protected by the surrounding leaf-sheaths. As soon as leaves
have grown fully, the internodes begin to elongate rapidly separating
the leaves. At first growth in length takes place throughout its length
in the internode and when it gets older this elongation ceases. But,
however, the lower portion of the internode close to the node and which
is enclosed by the leaf-sheath retains its power of growth for a
considerable time.

Branches arise from the axils of leaves and when a considerable number
of the axillary buds, especially from the lower nodes, develop into
branches the plant becomes tufted in habit. In most grasses branches
grow upwards through the sheath and emerge at its mouth as aerial
branches. Such branches are called =intravaginal= branches or stems. But
in some grasses axillary buds, instead of growing straight up through
the sheath, pierce the leaf-sheath, come out and then they grow out as
branches. This may be seen in the underground stolons of _Panicum
repens_ and in the ordinary aerial branches of _Arundo Donax_. Branches
that pierce through the sheaths are called =extravaginal= branches. (See
fig. 10.)

[Illustration: Fig. 10.--Extravaginal shoots of 1. Panicum repens and 2.
Arundo Donax.]

[Illustration: Fig. 11.--Nodes.

1. Glabrous node; 2. bearded node; 3. node cut longitudinally.]

The nodes are in most cases very conspicuous and they are often found
swollen. However, it must be remembered that the enlargement at the node
is not due to the increase in size of the actual node, but due to growth
in thickness of the base of the leaf-sheath. (See fig. 11-3.) Nodes may
be pale or coloured, glabrous, hairy or bearded with long hairs. When
the stem is erect the nodes are short and of uniform size all round.
But, if the stem is bent down or tipped over by accident, the nodes
begin to grow longer on the lower side until a curvature sufficient to
bring the stem to the erect position is formed and then it ceases to
grow.

As already noted some perennial grasses have creeping stems and stolons,
while others may have rhizomes. The grass _Cynodon dactylon_ develops
several underground stolons which are covered with white scale leaves
and whose terminal buds are hard and sharp so that they may be able to
make their way through the soil. The rhizomes when continuous and
elongated are usually sympodia formed by the lower portions of the
aerial shoots. The aerial shoot comes into the air and its lower portion
is continued by a branch arising from a lower leaf axil beneath the
soil.

=The leaf.=--Leaves are two-ranked and alternate, and very often they
become crowded at the lower portions of the shoots so as to form basal
tufts, though they are farther apart in the upper portions of these
shoots. Three distinct kinds of leaves are met with in grasses. First,
we have the fully formed foliage leaves so characteristic of grasses.
These are most conspicuous and are formed in large numbers.

The other two kinds of leaves are neither so conspicuous nor so numerous
as the foliage leaves. At the base of shoots occur abortive leaves which
are really rudimentary sheaths. These are called =scales=. The third
kind of leaf is a modified structure called the =prophyll= or
=prophyllum=. (See fig. 12.) It is the first leaf occurring in every
branch on the side next to the main shoot and it is a two-keeled
membranous structure resembling somewhat the palea found in the
spikelets of grasses. The portion of the prophyll between the keels is
concave due to the pressure of the main stem, while the sides beyond the
keels bend forward clasping the stem.

[Illustration: Fig. 12.--Prophylla.

A. A branch with its prophyllum; B. prophyllum; C. section of the
prophyllum.]

The ordinary foliage leaves of grasses consist of the two parts, the
flat expanded upper portion called the =blade= and the lower part called
the =sheath= that encircles the stem above the node from which it
arises. The leaf-sheaths usually fit close to the stem, but they may
also be loose or even inflated. Though the leaf-sheath surrounds the
internode like a tube, it is not a closed tube. It is really a flat
structure rolled firmly round the stem with one edge overlapping the
other. In most cases it is cylindrical and it may be compressed in a few
cases. Occasionally it may have a prominent ridge or keel down its back.
The sheath may be glabrous or hairy, smooth or striate externally, and
the outer margin is often ciliate. In a few grasses the sheaths become
coloured especially below or on the side exposed to the sun.

[Illustration: Fig. 13.--Ligules of 1. Oryza sativa; 2. Panicum
javanicum; 3. Andropogon Schoenanthus; 4. A. contortus.]

[Illustration: Fig. 14.--Shapes of leaf-blades.

1, 7 and 8. Lanceolate; 3 and 6. lanceolate-linear; 2 and 5. linear; and
4. ovate.]

The =ligule= is a structure peculiar to grasses and it varies very much.
In some grasses it is a distinct membrane narrow or broad, with an even,
truncate or erose margin, or finely ciliate. Very often it is only a
line or fringe of hairs, whilst in some it may be entirely absent as in
the leaves of _Panicum colonum_. When it is a membrane it may be broad
and oblong, ovate and obtuse, or lanceolate and acute. (See fig. 13.)
The function of the ligule is probably to facilitate the shedding of
water which may run down the leaf, and thus lessen the danger of rotting
of the stem which is sure to follow, if the water were to find its way
into the interior of the sheath. Sometimes, in addition to the ligule,
other appendages may be present in grass leaves as in _Oryza sativa_.
Such outgrowths are called =auricles= or =auricular outgrowths=. (See
fig. 13.)

The leaf-blade is well developed in the foliage leaves and in most cases
it follows directly on the sheath. But in bamboos and some species of
Ischaemum there occurs a short petiole or stalk between the leaf-blade
and the sheath. The sheath corresponds morphologically to the leaf base
of a leaf of other flowering plants.

[Illustration: Fig. 15.--Margins of leaves.

1 and 2. Finely serrate; 3. glandular; 4 and 5. very minutely serrate;
6. very minutely serrate and ciliate.]

In grasses the leaf-blades usually grow more in length than in any other
direction and there is no limit to the length they may attain. Some
grasses have very short leaves, others very long ones. The leaf-blade in
most grasses is more or less of some elongated form, such as linear,
linear-lanceolate, lanceolate, etc. (See fig. 14.) In a few grasses the
leaf-blade is ovate, but this is a rare condition. Therefore, in noting
the general shape of the leaf-blade the relation of the length to the
breadth, the amount of tapering towards the apex and base and the nature
of the apex should be considered.

The veins in the leaf-blade can usually be seen on holding the leaf up
to the light. All the veins run parallel. In most cases the midrib is
prominent and in some cases there may be also a distinct keel. Amongst
the veins running through the leaf-blade some are large and prominent,
while others are small and not conspicuous. On account of this
disparity, very often, ridges and furrows become prominent on the upper
or lower, or on both the surfaces of the leaf-blades. Generally the two
surfaces of the leaf-blade are distinct, and they may be glabrous or
hairy. In most grasses the surfaces are rough or scabrid to the touch
owing to the presence of regular rows of exceedingly fine sharp pointed
minute hairs.

The apex of the blade is generally sharp and pointed, acute or
acuminate, or sometimes it may be drawn to a very fine point by gradual
tapering. Blunt or obtuse tips are not altogether absent, but it is not
a common feature. The leaf-blades in _Panicum colonum_ and in some
species of Andropogon are rounded or obtuse at the apex.

The margins of the leaf-blade are somewhat hyaline and they may be
perfectly even or cut into serrations of fine teeth in various ways.
(See fig. 15.) In addition to these minute teeth, there may be long or
short cilia. Sometimes the margins are glandular as in _Eragrostis
Willdenoviana_ and _Eragrostis major_.

The base of the leaf may be narrower, broader than, or about the same as
the breadth of the leaf-sheath. It may be rounded, amplexicaul or
narrowed. At the base and just above the ligular region there will
always be a white distinct zone in the lamina of all grasses called the
collar. This collar varies in length and breadth according to the
species of grass.

[Illustration: Fig. 16.--Transverse section of leaf-buds.

A. Conduplicate; 1, 2 and 3. leaf-sheaths; 4 and 5. leaf-blades. B.
Convolute; 1 and 2, leaf-sheaths; 3 and 4. leaf-blades.]

In young shoots all the leaf-blades are usually found folded at the
terminal portions. In most cases the leaf-blade is rolled up inwards
from one end to the other so that one margin is inside and the other
outside. This folding is termed =convolute=. This is the kind of folding
that is found in most grasses. However, there are some grasses such as
_Eleusine aegyptiaca_ and _Chloris barbata_, in which the folding is
different. In these grasses the laminas are folded flat on their midribs
so that each half of the blade is folded flat on the other, the inner
surfaces being in contact. The leaves are said to be =conduplicate= in
this case. When the leaves are conduplicate the shoots are more or less
compressed. (See fig. 16.)




CHAPTER III.

THE INFLORESCENCE AND FLOWER.


The flowers of grasses are reduced to their essential organs, the
stamens and the pistil. The flowers are aggregated together on distinct
shoots constituting the inflorescence of grasses. Sooner or later all
the branches of a grass-plant terminate in inflorescences which usually
stand far above the foliage leaves. As in other flowering plants, in
grasses also different forms of inflorescence are met with. But in
grasses the unit of the inflorescence is the =spikelet= and not the
flower.

The forms of inflorescence usually met with are the spike, raceme and
panicle. When the spikelets are sessile or borne directly along an
elongated axis as in _Enteropogon melicoides_ the inflorescence is a
=spike=. If the spikelets borne by the axis are all stalked, however
short the pedicels may be, it is a =raceme=. It must, however, be
remembered that true spikes are very rare. An inflorescence may appear
to be a spike, but on a close examination it will be seen to consist of
spikelets more or less pedicelled. Such an inflorescence, strictly
speaking, is a =spiciform raceme=. The branches of the inflorescence in
_Paspalum scrobiculatum_ or _Panicum javanicum_ are racemes and the
whole inflorescence is a compound raceme. The inflorescence is a
=panicle= when the spikelets are borne on secondary, tertiary or further
subdivided branches. Panicles differ very much in appearance according
to the relative length and stoutness of the branches. In _Eragrostis
tremula_ the panicle is very diffuse, in _Eragrostis Willdenoviana_ less
so. The panicle in _Sporobolus coromandelianus_ is pyramidal and the
branches are all verticillate, the lower being longer than the upper.
The branches of a panicle are usually loose, spreading or drooping in
most grasses. But in some species of grasses such as _Pennisetum
Alopecuros_ and _Setaria glauca_, the paniculate inflorescences become
so contracted that the pedicels and the short branches are hidden and
the inflorescence appears to be a spike. Such inflorescences as these
are called =spiciform panicles=. The inflorescences in several species
of Andropogon consist of racemes so much modified as to appear exactly
like a spike. What looks like a spike in these cases consists of a
jointed axis and each joint bears a pair of spikelets, one sessile and
the other pedicelled.

The name =rachis= is given to the axis of the spike, raceme and panicle,
whether the axis is the main one or of the branch. The rachis of the
inflorescence is usually cylindrical. In some grasses it is zigzag as in
_Pennisetum cenchroides_. It is very much flattened in _Paspalum
scrobiculatum_, but somewhat trigonous in _Digitaria sanguinalis_. In
very many grasses the rachis is continuous, but in a few cases it
consists of internodes or joints which disarticulate at maturity. Many
species of Andropogon have such jointed rachises. Sometimes the joints
become greatly thickened and the surface hollowed out, the spikelets
fitting in the cavities as in Rottboellia and Manisuris.

In panicles, especially when they are diffuse, the primary branches may
be disposed irregularly or in verticils on the main axis. For example in
the panicle of _Eragrostis Willdenoviana_, the branches are irregularly
disposed, whereas in _Sporobolus coromandelianus_ the branches are
verticillate. In both these grasses fleshy cushions are developed in the
axils of the branches. These swellings help to spread out the branches
especially at the time of anthesis. The branches at the top spread out
earlier than those below.

Sometimes at the base of the rachises, main or secondary, glandular
streaks are seen as in the rachises of _Sporobolus coromandelianus_.
These glands secrete a viscid juice at the time of anthesis.

[Illustration: Fig. 17.--The Spikelet of Dinebra arabica.

1 and 2. Empty glumes; 3, 4, 5, and 6. flowering glumes with flowers.]

The =spikelet= may be considered as a specialised branch consisting of a
short axis, the =rachilla= bearing a series of modified bracts, the
=glumes=, the lower pair being empty but the others bearing flowers in
their axils. The glumes are two-ranked and imbricating. As a type for
the spikelet that of an Eragrostis or Dinebra may be chosen. (See fig.
17.) In this spikelet the rachilla bears a number of glumes alternating
and imbricating. The first two glumes at the base of the spikelet do not
bear any flowers and so these two glumes are usually called empty
glumes. This is the case in almost all the species of grasses. The third
and the subsequent glumes are regularly arranged on the slender rachilla
alternately in two rows. In the axils of each of these glumes there is a
flower, except perhaps in the topmost glume. The flower is usually
enclosed by the glume and another structure found opposite the glume and
differing very much from the glume. This is the =palea=. It is attached
to the axis of the flower and its back is towards the rachilla.
Generally there are two nerves in a palea and its margins are enclosed
within those of the glume. The palea is homologous with the prophyllum
which it very much resembles. The prophyllum is usually found in the
branches of grasses, but it is not confined to grasses alone. It occurs
in the branches of some species of Commelina.

The spikelets vary very much in their structure. The spikelets in
grasses of several genera consist of only four glumes. As usual the
first two glumes are empty and the remaining two are flower-bearing
glumes. Both these glumes may have perfect flowers as in Isachne or the
terminal one may contain a perfect flower, the lower having either a
staminate flower or only a palea. Very often the spikelets are unisexual
and the male and female spikelets may be on the same plant as in _Coix
Lachryma-Jobi_ and _Polytoca barbata_, or they may be on different
plants as in _Spinifex squarrosus_.

The glumes of a spikelet are really modified bracts and some
differentiate the flowering glumes from the empty ones, by giving them
different names. The first two empty glumes are called glumes by all
agrostologists. Some in Europe call the flowering glume lower palea to
distinguish it from the real palea which they call the upper palea. Some
American Authors have recently adopted for the flowering glume the term
=lemma= introduced by Piper.

Considerable variation is met with in the case of the empty glumes.
Generally they are unequal, the first being smaller. Very often the
first glume becomes very small and it may be altogether absent. In some
species of Panicum the first glume is very small, in Digitaria it is
very minute and in Paspalum and Eriochloa it is entirely suppressed. The
flowering glumes are generally uniform when there are many. In the
spikelet having only four glumes the fourth glume differs from the
others mainly in texture. Instead of being thin and herbaceous it
becomes rigid and hard, smooth or rugose externally as in Panicum.
Flowering glumes instead of being like empty glumes, become very thin,
shorter and hyaline in Andropogon. Sometimes the flowering glumes are
awned. All of them may be awned as in Chloris or only the fourth glume
as in Andropogon.

The palea is fairly uniform in its structure in many grasses, but it is
also subject to variation. It becomes shorter in some and is absent in
others. Instead of having two nerves, it may have one and rarely more
than two. The palea can easily be distinguished from the glume, because
its insertion in the spikelet is different from that of the glume.

[Illustration: Fig. 18.--Flower of Chloris.

1. lodicules; 2. stamens; 3. ovary.]

The =lodicules= are small organs and they are the vestiges of the
perianth. In most grasses there are only two, but in Ochlandra and other
bamboos we meet with three lodicules. There are also some species with
many lodicules. In shape they are mostly of some form referable to the
cuneate form. They are of somewhat elongated form in Aristida and
Chloris. The function of the lodicules seems to be to separate the glume
and its palea so as to enable the stamens to come out and hang freely at
the time of anthesis. So it is only at the time of the opening of the
flowers that the lodicules are at their best. Then they are fairly
large, fleshy and thick and conspicuous. In the bud stage they are
usually small and after the opening of the flower they shrivel up and
are inconspicuous. There are also species of grasses in which the
lodicules are not found.

The =stamens= are three in number in the majority of grasses and six are
met with in Leersia, Hygrorhiza and Bamboos. Each stamen consists of a
very delicate long filament and an anther basifixed to the filament. But
as the anthers are long and the connective is reduced to its minimum,
they appear as if versatile when the stamens are out. When there are
three stamens one stands in front of the flowering glumes and the other
two in front of the palea, one opposite each edge of the palea. The
relative positions of the parts of the floret are shown in the floral
diagrams. (See figs. 18 and 19.)

[Illustration: Fig. 19.--Floral diagrams.

The first is that of Chloris, second of Panicum and the third of Oryza.]

The =pistil= consists of an ovary and two styles ending in plumose
stigmas. The ovary is 1-celled and 1-ovuled. It is one carpelled
according to the views of Hackel and his followers and there are also
some who consider it as 3-carpelled because of the occurrence of three
styles in the pistil of some bamboos.

The =rachilla= is usually well developed and elongated in many-flowered
spikelets, while in 1-flowered spikelets it remains very small so that
the flower appears to be terminal. It often extends beyond the insertion
of the terminal flower and its glume, and then lies hidden appressed to
the palea. This may be seen in the spikelets of the species of Cynodon.
This prolonged rachilla sometimes bears a minute glume, which is of
course rudimentary. Usually the glumes are rather close together on the
rachilla so that the internodes are very short; but in some grasses, as
in _Dinebra arabica_, the glumes are rather distant and so the
internodes are somewhat longer and conspicuous. In some species of
Panicum the rachilla is jointed to the pedicel below the empty glumes,
whereas it is articulated just above these glumes in _Chloris barbata_.
Sometimes the rachilla is articulated between the flowers. This is the
case in the spikelet of _Dinebra arabica_.

Pollination in most grasses is brought about by wind, though in a few
cases self-pollination occurs. The terminal position of the
inflorescence, its protrusion far above the level of the foliage leaves,
the swinging and dangling anthers, the abundance of non-sticking pollen
and the plumose stigmas are all intended to facilitate pollination by
wind. Furthermore the stamens and the stigmas do not mature at the same
time. In some grasses the stamens mature earlier, (=protandry=) while in
others the stigmas protrude long before the stamens (=protogyny=). As
the result of the pollination the ovary developes into a dry 1-seeded
indehiscent fruit. The seed fills the cavity fully and the pericarp
fuses with the seed-coat and so they are inseparable. Such a fruit is
termed a =caryopsis= or =grain=. Though in the vast majority of grasses
the pericarp is inseparable, in a few cases it is free from the
seed-coat as in _Sporobolus indicus_ and _Eleusine indica_.

[Illustration: Fig. 20.--Longitudinal section of a portion of the grain
of Andropogon Sorghum. x 280 P. Pericarp; Sc. seed-coat; A. aleurone
layer; E. endosperm; S. scutellum; Rs. root-sheath; Rc. root-cap; R.
radicle; Pl. plumule; G. growing point.]

[Illustration: Fig. 21.--A portion of the section of the grain of
Andropogon Sorghum. x 500 P. pericarp; I. seed-coat; A. aleurone layer;
S. starch.]

The caryopsis consists of an embryo on one side at the base and the
endosperm occupies the remaining portion. The embryo can be made out on
the side of the grain facing the glume, as it is outlined as an oval
area. On the other face of the grain which is towards the palea, the
hilum is seen at the base. The grain varies in shape considerably. It
may be rounded, oval, ellipsoidal, narrow and cylindrical, oblong terete
or furrowed. There is considerable variation as regards the colour also.

The =embryo= consists of an =axis= and a =scutellum=. The axis, which is
differentiated into the plumule directed upward and the radicle
downward, is small and straight and it is covered more or less by the
edges of the scutellum. The scutellum is attached to the axis at about
its middle and its outer surface is in contact with the endosperm. This
is an important organ as its function is to absorb nourishment from the
endosperm during germination. The scutellum is considered to represent
the first leaf or cotyledon. The endosperm consists mostly of starch.
Just outside the endosperm and within the epidermis lies a layer of
cells containing much proteid substance. This layer is called the
=aleurone layer=. (See fig. 21.) As an illustration of the caryopsis,
the grain of Andropogon Sorghum may be studied. All the structural
details are shown in fig. 20 which is a longitudinal section of the
grain.

The primary axis of the embryo is enclosed by a closed sheath both above
and below. The sheath which envelopes the radicle is called =coleorhiza=
and that of the plumule, =pileole= or =germ-sheath=.




CHAPTER IV.

HISTOLOGY OF THE VEGETATIVE ORGANS.


The shoots and roots of grasses conform in their internal structure to
the monocotyledonous type. In all grasses numerous threads are found
running longitudinally within the stem and some of these pass into the
leaves, at the nodes, and run as nerves in the blades of the leaves.
These threads are the vascular bundles. The rest of the tissue of the
stem and leaves consists of thin-walled parenchymatous cells of
different sorts.

The general structure of these bundles is more or less the same in all
grasses. A vascular bundle consists of only xylem and phloem, without
the cambium, and so no secondary thickening can take place in the stems
of grasses. Such bundles as these are called =closed vascular bundles=
to distinguish them from the dicotyledonous type of vascular bundles
which are called =open vascular bundles= on account of the existence of
the cambium.

[Illustration: Fig. 22.--Transverse section of a vascular bundle. x 250

1. Annular vessel; 2. spiral vessel; 3. pitted vessel; 4. phloem or
sieve tubes; 5. sclerenchyma.]

The component parts and elements of which the vascular bundles in
grasses are composed may be learnt by studying the transverse and
longitudinal sections of these bundles in any grass. The cross and
longitudinal sections of a vascular bundle of the stem of _Pennisetum
cenchroides_, are shown in figs. 22 and 23. In the figure of the
transverse section the two large cavities indicated by the number 3 and
the two small circular cavities with thick walls lying between the
larger ones and indicated by the numbers 1 and 2 are the chief elements
of the xylem.

By looking at the longitudinal section it is obvious that these elements
are really vessels, the larger being pitted and the smaller annular and
spiral vessels. These vessels together with the numerous small
thick-walled cells lying between the pitted vessels constitute the
xylem. Just above the xylem there is a group of large and small
thin-walled cells. This is the phloem and it consists of sieve tubes and
thin-walled cells. All round the xylem and the phloem there are many
thick-walled cells. These are really fibres forming the =bundle-sheath=.
On account of this bundle-sheath the bundles are called =fibro-vascular
bundles=.

[Illustration: Fig. 23.--Longitudinal section of a vascular bundle. x
250

1. Annular vessel; 2. spiral vessel; 3. pitted vessel; 4. sieve tubes or
phloem; 5. sclerenchyma.]

[Illustration: Fig. 24.--Transverse section of a portion of the stem of
Rottboellia exaltata. x 70

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

=Structure of the stem.=--The stem of a grass consists of a mass of
parenchymatous cells with a number of fibro-vascular bundles imbedded in
it, and it is covered externally by a protective layer of cells, the
epidermis. The stem is usually solid in all grasses in the young stage,
but as it matures the internodes become hollow in many grasses and they
remain solid in a few. In the internodes the fibro-vascular bundles run
longitudinally and are parallel, but in the nodes they run in all
directions and form a net work from which emerge a few bundles to enter
the leaves. So far as the broad general features are concerned, the
stems of many grasses are more or less similar in structure. However,
when we take into consideration the arrangement of bundles, the
development and arrangement of sclerenchyma, every species of grass has
its own special characteristics. And these are so striking and constant
that it may be possible to identify the species from these characters
alone.

We may take as a type the stem of _Rottboellia exaltata_. This stem is
somewhat semi-circular in transverse section and it is almost straight
and flat in the front (the side towards the axillary bud). The
peripheral portion of the stem becomes somewhat rigid and thick due to
the aggregation of vascular bundles, some small and others large. The
outermost series of bundles consisting of small and larger bundles are
in contact with the layers of the cells lying just beneath the epidermis
and these cells are also thick-walled. A few are away from these being
separated by three or four layers of cells from the peripheral bundles.
In all these vascular bundles the bundle-sheath is very strongly
developed all round and is very much developed especially at the sides.
It is this great development of sclerenchyma that makes the outer
portion of the cortex hard. Within the ground tissue are found a number
of vascular bundles scattered more or less uniformly. These bundles have
no continuous bundle-sheaths but have instead groups of fibres at the
sides and in front of the phloem. The cavities near the annular vessels
are somewhat larger and conspicuous in these bundles.

[Illustration: Fig. 25.--Transverse section of the stem of Pennisetum
cenchroides. x 20]

The epidermal cells are all thickened very much and the outer layer is
cutinized and impregnated with silica. This is the case in the epidermis
of the stems and leaves of most grasses. (See fig. 24.)

In order to give a general idea of the variations in the structure of
the stem in grasses a few examples are chosen and the details of the
structure of the stems of these grasses are dealt with here.

[Illustration: Fig. 26.--Transverse section of a portion of the stem of
Pennisetum cenchroides. x 70

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

The stem of _Pennisetum cenchroides_ is somewhat round in outline in the
transverse section with a slight curvature in the front. The vascular
bundles are rather numerous and irregularly scattered all over the
ground tissue. The peripheral bundles are not so close to the periphery
of the stem as in _Rottboellia exaltata_. These are separated from the
epidermis by several layers of parenchymatous cells. Further, these
peripheral bundles are all imbedded in a continuous sclerenchymatous
band which runs round the stem in the form of a ring. The epidermal
cells as well as the layer of cells in immediate contact with it are
thick-walled. In the vascular bundles of the ground tissue the
bundle-sheath is rather prominent and the phloem portion is well
developed. (See figs. 25 and 26.)

[Illustration: Fig. 27.--Transverse section of the stem of Eriochloa
polystachya. x 25]

In the stem of _Eriochloa polystachya_, all the vascular bundles are
more or less peripheral in position leaving a wide area of
parenchymatous cells in the centre. The outline of the stem in cross
section is rotund or ovate-rotund with the front side somewhat flattened
and straight. The epidermal cells alone are thickened. A well developed
continuous ring of sclerenchyma is present and this is connected with
the epidermal layer at short intervals by means of short
sclerenchymatous bands. So the parenchymatous cells of the cortex lying
outside the sclerenchymatous ring are divided into small isolated areas.
There are three series of vascular bundles.

[Illustration: Fig. 28.--Transverse section of a portion of the stem of
Eriochloa polystachya. x 70

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

One series consists of small bundles lying inside the sclerenchyma ring
at the base of each of the connecting bands. The second series is made
up of large vascular bundles imbedded in the ring so as to bulge out
inside the ring. The vascular bundles of the third series are found just
away from the ring and separated from it by a few layers of
parenchymatous cells. (See figs. 27 and 28.)

[Illustration: Fig. 29.--Transverse section of the stem of Setaria
glauca. x 15]

[Illustration: Fig. 30.--Transverse section of a portion of the stem of
Setaria glauca. x 50

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

Another stem in which the vascular bundles are more or less peripheral
in position and enclosing a wide parenchyma is that of _Setaria glauca_.
In the transverse section of the stem the outline is ovate, laterally
compressed, obtusely keeled at the back and somewhat concave in the
front. The sclerenchymatous band is narrow and continuous and very close
to the epidermis, being separated from it only by two or three layers of
thin-walled cells. The epidermal cells alone are thickened. As to the
vascular bundles there are three sets. One set of bundles lying just
outside the sclerenchymatous ring consists of small ones connecting the
ring with the epidermis. Just inside the sclerenchymatous ring lies a
series of bundles which are connected with it. Still inside, at some
distance from the sclerenchymatous band, are seen vascular bundles
forming a row and enclosing a large space of the ground tissue
consisting of only parenchyma. (See figs. 29 and 30.)

[Illustration: Fig. 31.--Transverse section of the stem of Panicum
ramosum x 24]

[Illustration: Fig. 32.--Transverse section of a portion of the stem of
Panicum ramosum. x 75

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

[Illustration: Fig. 33.--Transverse section of the stem of Andropogon
caricosus. x 25]

The stem of _Panicum ramosum_ is semi-circular and somewhat flat on one
side. The epidermal cells alone are thickened. There is a broad well
developed continuous band of sclerenchyma, which is connected at regular
intervals with the epidermis by small vascular bundles. Another row of
vascular bundles lies just inside the sclerenchymatous ring and each of
these bundles is in contact with the band. Away from the ring lie a
number of bundles forming a series disposed in two irregular rings
around a broad portion of the ground tissue. (See figs. 31 and 32.)

[Illustration: Fig. 34.--Transverse section of a portion of the stem of
Andropogon caricosus. x 75

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

[Illustration: Fig. 35.--Transverse section of a portion of the stem of
Panicum Isachne. x 100

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

The stem of the grass _Andropogon caricosus_ is oval in outline, the
front being flat. The epidermal cells and those below and in contact
with them are thick-walled. The sclerenchymatous ring though present is
very narrow and not very conspicuous. It consists of one or two layers
of cells connecting a few vascular bundles forming the outermost set.
There is a series of vascular bundles inside the ring which surrounds a
large area of the ground tissue. Two isolated bundles, one in front and
another at the back of the ground tissue, are found. The cells of the
ground tissue lying just inside the vascular bundles are all very much
thickened. (See figs. 33 and 34.)

[Illustration: Fig. 36.--Transverse section of the stem of Eragrostis
interrupta. x 25]

[Illustration: Fig. 37.--Transverse section of the stem of Panicum
flavidum. x 15]

[Illustration: Fig. 38.--Transverse section of a portion of the stem of
Panicum flavidum. x 70

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

The stems of _Panicum Isachne_ and _Eragrostis interrupta_ are hollow.
The stem of the former is circular in outline in cross section, though
wavy. There is a sclerenchymatous ring close to the epidermis but
separated from it by a few layers of parenchyma. One set of bundles is
imbedded in the band, and another set just touches the inner border of
it. A third series is disposed around a fairly large amount of ground
tissue, which may or may not have a cavity in the centre. The stem of
_Eragrostis_ _interrupta_ has more or less the same structure, but the
cortex has air spaces here and there. Other minor differences may be
seen on referring to figs. 35 and 36.

[Illustration: Fig. 39.--Transverse section of a portion of the stem of
Panicum colonum. x 70

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

The stems of grasses growing in wet or marshy situations differ in
structure from those detailed above. As examples the stems of _Panicum
flavidum_, _Panicum colonum_, _Panicum Crus-galli_ and _Panicum
fluitans_ may be considered. The stem of _Panicum flavidum_ is broadly
ovate in cross section with a flat front and is more or less solid,
though occasionally the parenchymatous cells in the centre get broken.
Two rows of vascular bundles surround a fairly large amount of
parenchymatous cells of the ground tissue. There is a continuous ring of
sclerenchyma separated from the epidermis by a fairly broad cortex. The
cortex has a number of fairly large air-cavities separated by bands of
parenchymatous cells. Within the sclerenchymatous band lie small
vascular bundles at regular intervals just towards the cortex. A few
isolated bundles are in contact with the inner border. (See figs. 37 and
38.)

The stems of _Panicum colonum_, _Panicum stagninum_ and _Panicum
Crus-galli_ have in their centre in the ground tissue stellate cells
with air-cavities. This part is surrounded by a fairly broad portion of
parenchymatous cells in which are imbedded two rows of bundles. Outside
these bundles runs round the stem a narrow sclerenchymatous band with a
few bundles in it of which some touch it inside and others outside. Two
bundles are found by themselves in the tissue of stellate cells. In
_Panicum Crus-galli_ three or four bundles are met with amidst the
stellate cells.

[Illustration: Fig. 40.--Transverse section of a portion of the stem of
Panicum Crus-galli. x 70

1. Epidermis; 2. sclerenchyma; 3. vascular bundle.]

[Illustration: Fig. 41.--Transverse section of the stem of Panicum
stagninum. x 10]

The cortex outside the band of sclerenchyma is full of air-cavities,
small and large. In _Panicum colonum_ the outline of the stem is
ellipsoidal with the front quite flat, and the cortex is narrow at the
sides and very broad in front and at the back. The sclerenchymatous ring
is circular in outline. The stem of _Panicum Crus-galli_ is broadly
ovoid and the cortex is uniformly broad. The epidermal cells as well as
the lower cells are thickened in the stems of _Panicum fluitans_ and
_Panicum Crus-galli_, but in the stems of _Panicum colonum_ and _Panicum
flavidum_ the epidermis alone is thickened. In the cortical portion
outside the sclerenchymatous band, small vascular bundles occur in the
stems of _Panicum colonum_, _Panicum Crus-galli_ and _Panicum fluitans_.
(See figs. 39, 40, 42 and 43.)

[Illustration: Fig. 42.--Transverse section of the stem of Panicum
fluitans. x 15]

[Illustration: Fig. 43.--Transverse section of a portion of the stem of
Panicum fluitans. x 60

1. Epidermis; 2. sclerenchyma; 3. vascular bundle; 4. air-cavity; 5.
diaphragm.]

The stem of _Panicum fluitans_ is round in outline in the transverse
section and has a large cavity. Just close to the cavity and separated
from it by only one or two parenchymatous cells are found vascular
bundles forming a series. Outside this series of bundles lies a
sclerenchymatous band which is wavy, following the lower edges of the
large air-cavities. One series of bundles is connected with this
sclerenchymatous ring. The air-cavities are large and uniform and are
separated by bands of parenchymatous cells. In each of these bands lies
a vascular bundle on the upper side near the periphery. Sometimes we
find, especially in young stages, diaphragms of stellulate cells
stretched across the air-cavities. Later as the stem matures these
disappear and the cavities become conspicuous. (See figs. 42 and 43.)

=Structure of the root.=--As already stated, the roots of grasses
conform to the monocotyledonous type, but the variations met with in
their structure are not so great as in the case of the stem. The
root-tips are protected by root-caps, and the actual tip of the root is
very distinct in the roots of all grasses and it can be seen very
clearly in a longitudinal section of the root. The actual tip of the
root is sharply distinct from the root-cap as there are two distinct
sets of cells, one giving rise to the root-tip and the other to the
root-cap.

The young root-tips are always free from root-hairs, and they are
confined to the portions behind the root-tips. The extent of the
root-hair region will vary according to the vigour and development of
the roots and the nature of the soil. The root-hairs are mere
protrusions of the cells of the outermost layer of the cortex of the
root and this layer is called the =piliferous layer=.

[Illustration: Fig. 44.--Transverse section of a part of the root of
Pennisetum cenchroides. x 100

1. Root-hair; 2. piliferous layer; 3. cortex; 4. endodermis; 5.
pericycle; 6. xylem; 7. phloem.]

To learn the structure of the roots of grasses we may select as types
the roots of _Pennisetum cenchroides_ and _Andropogon Sorghum_ and
consider their structural details. In the transverse sections of these
roots we find a fairly broad cortex consisting of thin-walled
parenchymatous cells more or less regularly arranged. (See figs. 44 and
45.) Just below the piliferous layer two or three layers of thick-walled
cells are seen. In the roots of _Andropogon Sorghum_ these thick-walled
cells are very conspicuous as they consist of several layers. These
layers of thick-walled cells constitute the =exodermis=. (See fig. 46.)
The innermost layer of cells of the cortex is called the =endodermis=
and it becomes conspicuous on account of the thickening in the lateral
and inner walls of the cells of this layer. (See figs. 44 and 47.)

[Illustration: Fig. 45.--Transverse section of the entire root of
Andropogon Sorghum. x 25]

[Illustration: Fig. 46.--Transverse section of the cortical portion of
the root of Andropogon Sorghum. x 150

r.h. Root-hair; p.l. piliferous layer; ex. exodermis; co. cortex.]

The rest of the root forming the central core is the stele and at its
periphery there is a single layer of cells called the =pericycle=. The
arrangement of the xylem and the phloem is different from that of the
stem. They lie side by side on different radii, and not one behind the
other on the same radius as in the stem. The number of xylem groups is
fairly large and the development of the xylem is from the pericycle
towards the centre of the stele. (See figs. 44 and 45.) The
parenchymatous cells in the centre of the stele become thick-walled in
older roots.

=Structure of the leaf.=--The structure of the leaf of grasses is quite
characteristic of the family. In every leaf a number of vascular
bundles, some small and others large, pass from the base to the apex.
Externally the leaf is covered on both the sides by the epidermis. The
spaces existing between the vascular bundles and the epidermis are
filled with parenchymatous cells. The larger vascular bundles consist of
xylem and phloem surrounded by a bundle sheath of a single layer of
cells. In the smaller bundles the xylem is very much reduced. Around
every vascular bundle there is a single row of somewhat large cells
densely packed with large chloroplasts, the =chlorophyllous layer=. The
vascular bundles are strengthened by fibres, on both the sides in the
case of larger bundles and on only one side in small bundles.

[Illustration: Fig. 47.--Transverse section of the stele portion of the
root of Andropogon Sorghum. x 150

Co. Cortex; en. endodermis; pe. pericycle; ph. phloem; pr. protoxylem;
xy. xylem vessel.]

[Illustration: Fig. 48.--A portion of the transverse section of the leaf
of Panicum javanicum. x 100

Ep. c. An ordinary epidermal cell; st. stomata; sc. sclerenchyma; ph.
phloem; chl c. chlorenchyma; m. motor cells; xy. xylem.]

For a detailed study of the structure of the leaves of grasses the leaf
of the grass _Panicum javanicum_ may be chosen. In a transverse section
of this leaf, the vascular bundles are very conspicuous. The larger
bundles are normal in every way, while in the smaller ones the xylem
elements are considerably reduced. Around every one of the vascular
bundles there is a single row of large cells containing large
chlorophyll grains (the chlorophyllous layer). In a well developed large
vascular bundle the chlorophyllous layer is open below just close to the
sclerenchymatous band. On both sides of the larger vascular bundle there
are bands of sclerenchyma. In the case of smaller bundles some are
strengthened by sclerenchyma on the lower side and others have none. The
spaces between the bundles are occupied by thin-walled parenchymatous
cells containing small chlorophyll grains.

[Illustration: Fig. 49.--Upper epidermis of the leaf of Panicum
javanicum. x 300]

[Illustration: Fig. 50.--Lower epidermis of the leaf of Panicum
javanicum. x 300]

The lower epidermis of the leaf in the transverse section is even and
consists of small and large round cells. The upper epidermis is slightly
wavy and it is made up of some small round cells alternating with groups
of larger cells. The epidermal cells lying over sclerenchyma and the
smaller vascular bundles are small and round, while those lying over the
furrows between the vascular bundles are large and are called =motor= or
=bulliform cells=. The presence of motor cells is a characteristic
feature of the leaves of many grasses.

The continuity of both the upper and the lower epidermis is interrupted
by the stomata. Air-cavities are seen below these stomata. The
arrangement of the stomata, the shape of the guard cells and the
characteristics of the epidermal cells become clear on examining a piece
of epidermis. (See figs. 49 and 50.)

The structure of the leaf of _Panicum javanicum_ may be taken as typical
of the structure of the leaves of most grasses. The leaves of _Eriochloa
polystachya_, Cynodon and Paspalums are very much like the leaves of
_Panicum javanicum_ in their internal structure.

Considerable amount of variation, however, occurs in the leaves of
grasses especially as regards the arrangement of fibres and motor cells.

[Illustration: Fig. 51.--A portion of the transverse section of the leaf
of Eriochloa polystachya x 120

1. Motor cell; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer.]

Every large primary vascular bundle in the leaves of many grasses
possesses sclerenchymatous bands both above and below. The other
vascular bundles may have bands of sclerenchyma on both sides or on one
side only or none. For example, in the leaves of _Panicum repens_ both
the primary and secondary bundles are provided with sclerenchyma on both
the sides, while those of the third order may have it on one side or
not. The hyaline margin of this leaf and of the leaves of other grasses
consists entirely of sclerenchyma. (See fig. 53.)

[Illustration: Fig. 52.--Transverse section of a portion of the leaf of
Panicum repens. x 120

1. Motor cells; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer.]

All the vascular bundles in the leaves of _Aristida setacea_ have broad
sclerenchymatous bands on both the sides. Besides these bands arranged
like a girder above and below each bundle, there are on the lower side
bands of sclerenchyma. So the sclerenchyma becomes almost continuous on
the lower side.

[Illustration: Fig. 53.--Transverse section of the leaf margin of
Panicum repens. x 180

1. Sclerenchyma; 2. stomata; 3. chlorophyllous layer.]

[Illustration: Fig. 54.--Transverse section of a part of the leaf of
Aristida setacea. x 30.

1. Vascular bundle; 2. sclerenchyma; 3. motor cells.]

[Illustration: Fig. 55.--Transverse section of a portion of the leaf of
Aristida setacea. x 120

1. Motor cells; 2. stomata; 3. sclerenchyma; 4. epidermis; 5. cutin
layer.]

The sclerenchyma lying on the lower side of the primary bundles are
contiguous with the bundle, while those above are separated from the
bundle by the chlorophyllous layer. (See fig. 55.) In the case of
secondary and tertiary bundles the sclerenchymatous bands lying on the
lower side are in contact with the chlorophyllous layer, whereas the
upper bands are either in contact with this layer or separated from it
by a few parenchymatous cells.

All the vascular bundles in the leaves of _Eragrostis Willdenoviana_ are
provided with sclerenchyma on both the sides. The lower band of the
primary vascular bundles is continuous with the vascular bundle, the
chlorophyllous layer being open below. The upper bands of the primary
and the lower bands of the secondary vascular bundles just touch the
chlorophyllous layer. In the secondary bundles the sclerenchyma band
above is separated from the chlorophyllous layer by two layers of
parenchyma. In the case of the leaves of _Panicum flavidum_, _P.
colonum_, _P. fluitans_ and _Pennisetum cenchroides_ the sclerenchyma is
separated from the chlorophyllous layer by layers of parenchyma.

[Illustration: Fig. 56.--Transverse section of a part of the leaf of
Eragrostis Willdenoviana. x 30

1. Vascular bundle; 2. sclerenchyma; 3. motor cells.]

[Illustration: Fig. 57.--Transverse section of a portion of the leaf of
Eragrostis Willdenoviana. x 150

1. Motor cells; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer; 5.
vascular strand cut through; 6. hair.]

[Illustration: Fig. 58.--Transverse section of a part of the leaf of
Panicum colonum. x 30

1. Vascular bundle; 2. sclerenchyma; 3. motor cells.]

Even from the few examples dealt with above, it is obvious that the
range of variation of sclerenchyma in leaves is very great. In the
leaves of _Aristida setacea_ there is a considerable amount of
sclerenchyma whilst in some leaves such as those of _Panicum_ _colonum_,
_P. flavidum_ and _Panicum fluitans_ the sclerenchyma is reduced to its
minimum.

[Illustration: Fig. 59.--Transverse section of a part of the leaf of
Panicum fluitans. x 30

1. Vascular bundle; 2. sclerenchyma.]

In the leaves of grasses growing in dry situations the development of
sclerenchyma is generally very considerable. The grass _Aristida
setacea_ is a good example of a xerophytic grass. The sea-shore grass
_Spinifex squarrosus_ is another example of the same kind. But in the
leaves of this grass, the development of sclerenchyma is not very
considerable, but there is a great development of parenchymatous cells
free from chlorophyll within the leaf, the chlorophyll bearing cells
being confined to the upper and the lower surfaces of the leaves.

[Illustration: Fig. 60.--Transverse section of a leaf of Spinifex
squarrosus. x 10

1. Vascular bundle; 2. sclerenchyma.]

[Illustration: Fig. 61.--A portion of the transverse section of the leaf
of Spinifex squarrosus. x 60

1. Sclerenchyma; 2. vascular bundle; 3. epidermis; 4. stomata.]

The upper and the lower surfaces of the leaves of many grasses are more
or less even, but in the case of a few grasses the upper surface
consists of ridges and furrows, instead of being even. In the leaves of
_Panicum repens_ and _Eragrostis Willdenoviana_ the upper surface is
wavy and consists of shallow furrows and slightly raised ridges. But in
the leaves of _Aristida setacea_ and _Panicum fluitans_ the furrows are
deeper and the ridges are more prominent. In _Aristida setacea_ the
ridges are flat-topped and they are rounded with broad furrows in
_Panicum fluitans_.

[Illustration: Fig. 62.--Upper epidermis of the leaf Panicum Isachne. x
200

1. Cells overlying the veins; 2. cells overlying the furrows; 3.
stomata.]

[Illustration: Fig. 63.--Lower epidermis of the leaf Panicum Isachne. x
200

1. Cells overlying the veins; 2. cells overlying the furrows; 3.
stomata.]

The epidermis covering the leaves consists of elongated cells with plane
or sinuous walls, various kinds of short cells intercalated between the
ends of long cells, motor-cells and stomata. Hairs of different sorts
occur as outgrowths of the epidermis. The roughness of the surface of
the leaves of grasses is due to the presence of very minute short hairs
borne by the epidermis. In most cases these short hairs are found in
regular rows. Although the epidermis is more or less even in the leaves
of several grasses such as _Panicum repens_, _P. flavidum_ and
_Eriochloa polystachya_, it is wavy or undulating in the leaves of a few
grasses. For example, the upper epidermis in the leaves of _Panicum
fluitans_ is undulating as it follows the contour of the ridges and
furrows.

The epidermal cells have even surfaces in the leaves of most grasses but
in some they bulge out. In the leaves of _Panicum flavidum_ the cells of
the lower epidermis are quite even, whilst those of the upper epidermis
bulge out. The cells of both the upper and the lower epidermis are
distinctly bulging out in the leaves of _Panicum colonum_. In _Panicum
fluitans_ the cells of the upper epidermis bulge out so much as to form
distinct papillae.

The free surface of the epidermis is more or less cutinised in the
leaves of all grasses. In some leaves the cuticle is very thick and even
papillate as in the leaves of _Aristida setacea_ and _Panicum repens_
whilst in others it is very thin, as in the leaves of _Panicum colonum_
and _P. fluitans_. Cutinisation is rather prominent in the leaves of
grasses growing under dry conditions and it is less pronounced in
mesophytic grasses.

[Illustration: Fig. 64.--Transverse section of a portion of the leaf of
Panicum colonum. x 120

1. Motor cells; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer.]

[Illustration: Fig. 65.--Transverse section of a portion of the leaf of
Panicum fluitans. x 120

1. Motor cells; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer.]

As regards size, the epidermal cells overlying the sclerenchyma are
small and those lying over parenchyma are larger. Amongst the larger
cells some may be motor-cells. The stomata occur in regular rows between
the vascular bundles and they are quite characteristic of grasses. They
are more or less similar in structure in all grasses. In the leaves of
many grasses stomata are found in both the upper and the lower epidermis
and they are confined to the lower epidermis in a few grasses only.

The motor-cells vary very much both as regards their shape and position.
In some leaves as in the leaves of the grass _Panicum flavidum_ the
motor-cells are confined to the midrib on the upper surface.

The epidermal cells of this leaf are large and uniformly round. (See
figs. 66 and 67.)

[Illustration: Fig. 66.--Transverse section of a leaf of Panicum
flavidum. x 20

1. Vascular bundle; 2. sclerenchyma; 3. motor-cells.]

[Illustration: Fig. 67.--Transverse section of the leaf of Panicum
flavidum. x 150

1. Motor-cells; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer.]

In the case of most grasses the motor-cells are found in groups of
three, four or five between the vascular bundles. The central motor-cell
is usually the largest and it is somewhat obovate in shape in a
transverse section of the leaf. In the leaves of _Panicum javanicum_ and
_Eriochloa polystachya_ there are three or four motor cells in the group
and the group consists of four, five or rarely six motor cells in the
leaves of _Eragrostis Willdenoviana_. When there are distinct furrows
between ridges these cells lie in the furrows and they are many in
number. In the leaves of _Panicum repens_ there are five to seven
motor-cells in the furrows and the single row of cells stretched between
the motor-cells and the lower epidermis in the furrow consists of more
or less clear cells with sparsely scattered small chlorophyll grains.
(See fig. 52.) The motor-cells occupying the furrows in the leaves of
_Aristida setacea_ are more in number than in _Panicum repens_ and are
of a different shape. All the cells lying in the furrow between the
motor-cells and the sclerenchyma are clear cells free from chlorophyll
grains.

Although the motor-cells differ in shape from the ordinary epidermal
cells in most grasses, there are, however, a few grasses in which the
motor-cells do not differ very much from the epidermal cells except in
size. For example, in the leaves of _Panicum colonum_ the motor-cells
are just like the ordinary epidermal cells in shape but are larger. (See
fig. 64.)

Motor-cells are usually confined to the upper epidermis, but they may
also be found in the lower epidermis. In the leaves of _Pennisetum
cenchroides_ motor-cells are found in both the upper and the lower
epidermis, the group in the upper epidermis alternating with that in the
lower.

[Illustration: Fig. 68.--Transverse section of a portion of the leaf of
Pennisetum cenchroides. x 100

1. Motor-cells; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer.]




CHAPTER V.

CLASSIFICATION.


The family Gramineae is usually divided into two series taking into
consideration the presence or absence of a joint in the pedicel or
rachis, the number of flowers in the spikelet and the position of the
fertile flower. All the species in which there is a joint just below the
spikelet, in the pedicel, in the rachis, or at the base of a cluster of
spikelets come under one series =Panicaceae=. The spikelets of the
grasses coming under this series, when mature, fall away singly by
themselves, or with their pedicels, or in groups with portions of the
rachis. The spikelets are all similar and consist of usually four
glumes. Each spikelet contains a single perfect flower and sometimes in
addition a staminate flower just below the perfect flower. In this
series the tendency for imperfection is always confined to the lower
flowers, the terminal flower alone being perfect. For inclusion under
this series the grass plant should have both the characters,
articulation and position of the flower as mentioned above.

The second series =Poaceae= includes those grasses in which the spikelets
are one to many-flowered and continuous with their pedicels. But the
rachilla of the spikelet may be jointed just above the empty glumes or
between the flowering glumes. The complete flower is the lowest and the
tendency for imperfection is in the upper flowers.

Of the two series the Panicaceae appears to be more highly developed than
the Poaceae.

KEY TO TRIBES.

Series I.--Panicaceae.

  A. Rachis of inflorescence not jointed.

    Spikelets 2-flowered; upper flower
    bisexual and lower male or neuter;
    the first glume the smallest                  I. Paniceae.

    Spikelets 1-flowered;

      Spikelets articulate on their
      pedicels and falling away from
      them; flowers bisexual and
      usually with six stamens                   II. Oryzeae.

      Spikelets falling away with their
      pedicels; flowers bisexual or
      rarely imperfect                          III. Zoysieae.

  B. Rachis of inflorescence usually
  jointed.

    Spikelets usually binate (3-nate at
    the top), pairs of spikelets alike
    or dissimilar; empty glumes
    larger and the flowering glumes
    smaller, hyaline, the fourth glume
    awned or reduced to an awn                   IV. Andropogoneae.

Series II.--Poaceae.

  A. Rachilla produced or not beyond the
  flowering glume.

    Spikelets 1-flowered, with three
    glumes; first and second empty,
    third flowering and awned;
    rachilla jointed                              V. Agrostideae.

    Spikelets 1- or more-flowered,
    biseriate and secund on an
    inarticulate spike or on the
    spiciform branches of a slender
    panicle; flowers all or the
    lower only bisexual                          VI. Chlorideae.

  B. Rachilla produced beyond the uppermost
  flowering glume and articulate.

    Spikelets 2- or more-flowered,
    pedicelled, rarely sessile, in
    effuse, contracted or rarely
    spiciform panicles                          VII. Festucaceae.

    Spikelets 1- or more-flowered,
    sessile, 1- to 2- or more-seriate on
    the rachis of a simple spike, or
    partially sunk in cavities of the
    same. Glumes awned or not,
    first and second glumes are
    opposite or subcollateral,
    persistent or separately deciduous;
    first glume minute or absent               VIII. Hordeae.




CHAPTER VI.

Series I--Panicaceae.

TRIBE I--PANICEAE.


This is a fairly large and important tribe flourishing mostly in the
warm regions and the tropics. It is very well represented in South India
and fifteen genera are met with.

The inflorescence varies very much within this tribe and consists of
spikes, racemes and panicles. The spikelets are usually four-glumed and
contain one terminal perfect flower and a staminate or neutral flower
below. But in the genus Isachne both the flowers are perfect. In some
grasses the spikelets contain only staminate or pistillate flowers. In
Coix and Polytoca the plant bears both male and female spikelets in the
same inflorescence, but in Zea on the same plant they occur as distinct
inflorescences. The littoral grass Spinifex is dioecious.

The first glume of the spikelet is the smallest. In Panicum it is nearly
two-thirds or less than the third glume. It is very small in Digitaria
and entirely suppressed in Paspalum. In Eriochloa it is reduced to a
minute ridge lying just close to the swollen ring-like joint of the
rachilla. The second and the third glumes are more or less equal and
similar in texture. The fourth glume becomes firm and rigid along with
its palea and usually encloses the grain.

The pedicel is jointed in some genera and in others it is continuous
with the spikelet and not jointed. When mature the spikelets fall away
either by themselves, singly with their pedicels or in groups with
portions of rachis, according to the position of the joint. Bristles
(branchlets) are often found on the pedicels. In Setaria a few are borne
by the pedicels. The bristles form a regular involucre at the base of a
group of spikelets in Pennisetum, and in Cenchrus these become united at
the base into a mass forming a kind of burr around the spikelets.

KEY TO THE GENERA.

  A. Spikelets articulate on their pedicels.

    B. Spikelets without involucels.

      C. Spikelets dorsally flattened, awnless.

	Inflorescence racemed; glumes
	three; nerves of second glume
	five or less, side nerves curved            1. Paspalum.

	Inflorescence digitate; glumes
	three with a minute glume;
	nerves of second glume five to
	seven, straight and prominent               2. Digitaria.

	Inflorescence panicled; glumes
	three with a thickening at the
	base of the spikelet                        3. Eriochloa.

	Inflorescence racemed or paniculate;
	glumes four, first two glumes
	unequal                                     4. Panicum.

	Inflorescence panicled, branches of
	panicle produced beyond the
	uppermost spikelet; glumes four,
	the first being minute and hyaline          5. Chamaeraphis.

	Spikelets unisexual and dioecious           6. Spinifex.

      CC. Spikelets awned.

	Glumes four, second glume broadly
	fimbriate with hairs; palea of
	the third glume short and deeply
	cleft, fourth glume awned                   7. Axonopus.

    BB. Spikelets involucellate                     8. Setaria.

  AA. Spikelets not jointed but continuous.

	Spikelets in involucelled deciduous
	fascicles.

          Involucre of bristles free                9. Pennisetum.

          Involucre of bristles united             10. Cenchrus.



1. Paspalum, _L._

These are annuals or perennials. The spikelets are plano-convex,
orbicular to oblong, obtuse, secund, 2-ranked on the flattened or
triquetrous rachis of the spike-like branches of a raceme, one-flowered
and falling off entire from the very short or obscure pedicels. There
are three glumes, all more or less equal and similar. The first and the
second glumes are membranous, alike and as long as the third, the second
glume is usually epaleate and occasionally with a minute palea. The
third glume is chartaceous to sub-coriaceous and paleate. Lodicules are
two and small. Stamens are three. The styles are slender and distinct
with plumose stigmas exserted at the top of the spikelet. Grain is
tightly enclosed in the third glume and its palea.

[Illustration: Fig. 69.--Paspalum scrobiculatum.]


=Paspalum scrobiculatum, _L._=

This is an annual grass, with stems tufted on very short rhizomes, erect
or very shortly bent at base, glabrous, bifariously leafy and varying in
height from 1 to 3 feet or more.

_Leaf-sheaths_ are compressed, glabrous, loose, keeled, mouth hairy or
not. The _ligule_ is a short thin membrane. The _nodes_ are glabrous.

The _leaf-blade_ is linear-lanceolate, finely acuminate, keeled with a
distinct midrib, and with very minutely serrulate margins, 6 to 18
inches by 1/12 to 1/3 inch.

The _inflorescence_ consists of 2 to 5 sessile alternate spikes, usually
distant and spreading and varying in length from 1 to 8 inches; the
rachis is flattened and winged.

The _spikelets_ are either orbicular or ovate-oblong, as broad as the
rachis, glabrous, closely imbricating in two rows (rarely in three or
four rows), sessile or rarely geminate on a common pedicel.

There are three glumes. The _first glume_ is concave, 3- to 5-nerved
(rarely 3- to 7-nerved). The _second glume_ is flat, 5-nerved, with two
strong sub-marginal nerves, sometimes with shallow transverse pits along
the margins. The _third glume_ is thickly coriaceous, brownish, shining,
minutely striolate, margins roundly incurved throughout its length,
paleate; the _palea_ is similar to the glume in structure and colour,
margins strongly inflexed and with two broad membranous auricles almost
overlapping just below the middle. There are three _stamens_. The
_stigmas_ are white both when young and while fading. The style branches
are diverging widely and then straight. There are two oblong cuneate
fleshy _lodicules_.

[Illustration: Fig. 70.--Paspalum scrobiculatum.

1 and 2. Front and back view of a portion of spike; 3, 4 and 5.
spikelets; 6, 7 and 8. the first, second, and the third glume,
respectively; 9. palea of the third glume; 10. the ovary, stamens and
the lodicules.]

This grass flourishes all over the Presidency in moist places, such as,
bunds of wet lands, edges of ponds and lakes and in marshy land. There
are two forms of this grass, one with round and another with ovate
oblong spikelets. They also vary in the size of the spikelets--some
forms have small spikelets and others large. Sometimes the spikelets
show variation in the number of glumes.

This grass is also cultivated for its grain. In cultivated forms the
spikelets are larger and the whole plant grows bigger. It is grown both
in wet and dry land.

_Distribution._--Throughout India (wild and also cultivated).



2. Digitaria, _Rich._

Annuals or perennials. The spikelets are lanceolate, 2- to 3-nate, in
digitate or racemose spikes, jointed on the pedicels but not thickened
at the base, 1-flowered. There are usually four dissimilar glumes in the
spikelet. The first glume is hyaline very minute, sometimes absent in
the same species. The second glume is membranous, 1- to 5-nerved or
nerveless. The third glume is membranous, almost equal to the fourth,
usually 7- to 9-nerved, the nerves being straight, close, parallel and
prominent, with a minute palea or without a palea. The fourth glume is
chartaceous or sub-chartaceous, usually 3-nerved and paleate; palea is
equal to and similar to the fourth glume, 2-nerved. Lodicules are two,
small, broadly cuneate. Stamens are three. Styles are distinct with
plumose stigmas exserted laterally near the apex of the spikelet. Grain
is enclosed in the fourth glume and its palea.

KEY TO THE SPECIES.

  Spikelets 1/10 inch or more.

      Spikes usually few, spikelets
      bearded                          1. D. sanguinalis. Var. ciliaris.

      Spikelets not bearded            2. Do. Var. extensum.

      Spikes usually many; spikelets
      spreading                        3. Do. Var. Griffithii.

  Spikelets less than 1/10 inch.

      Spikes narrowly winged;
      spikelets subsilky with
      slender (not clavellate)
      hairs                            4. D. longiflora.

[Illustration: Fig. 71.--Digitaria sanguinalis, _Var. ciliaris_.]


=Digitaria sanguinalis, _Scop._=

_Var. ciliaris._

This is an annual grass either with erect tall stems or long prostrate
stems, varying in length from 1 to 3 feet or more.

The _leaf-sheath_ is herbaceous, loose and glabrous. The _ligule_ is a
distinct membrane. The _nodes_ are glabrous.

The _leaf-blade_ is linear-lanceolate or linear, flat, glabrous or very
sparsely hairy, varying in length from 2 to 5 or 6 inches and in breadth
from 1/6 to 1/3 inch.

The _spikes_ are usually few, 2 to 6, 3 to 6 inches long, with a
triquetrous, narrowly winged rachis.

The _spikelets_ are oblong, acute, binate, one pedicel being shorter
than the other, usually appressed to the rachis and not spreading.

[Illustration: Fig. 72.--Digitaria sanguinalis. _Var. ciliaris_.

1. A portion of the spike showing the binate spikelets; 2. a spikelet;
3. the minute scale-like first glume; 4, 5 and 6. the second, third and
the fourth glume, respectively; 7. the palea of the fourth glume.]

There are four _glumes_ including the minute glume. The _first glume_ is
a very minute scale. The _second glume_ is about half as long as the
third glume, membranous, usually 3-nerved and sometimes 3- to 5-nerved,
distinctly ciliate. The _third glume_ is oblong-lanceolate, acute,
membranous, 3- to 5-nerved, sparingly hairy in the lower spikelet and
densely bearded with soft spreading hairs in the upper spikelet. The
_fourth glume_ is lanceolate, or oblong-lanceolate, acute, somewhat
chartaceous, paleate; _palea_ is like the glume in texture. _Anthers_
are pale yellow. _Stigmas_ are white. There are two small cuneate
_lodicules_.

This is an excellent fodder grass. It grows well in all kinds of soils,
rich or poor, and is very common in dry fields brought under
cultivation.

_Distribution._--Throughout India.


=Digitaria sanguinalis, _Scop._=

_Var. Griffithii._

This is an annual with stems ascending from a prostrate or geniculate
base, glabrous and varying in length from 1 to 3 feet.

The _leaf-sheath_ is glabrous, thinly herbaceous and loose. The _ligule_
is a distinct membrane and the _nodes_ are glabrous.

The _leaf-blade_ is linear or linear-lanceolate, flat, acuminate,
varying in length from 2 inches to 12 inches and in breadth 1/6 to 1/3
inch.

The _inflorescence_ is of several slender spikes, usually drooping, 2 to
4 inches; the rachis is filiform and trigonous.

The _spikelets_ are linear-lanceolate, solitary or in distant pairs,
glabrous or ciliate, pedicelled and when binate the upper pedicel often
longer than the spikelets, usually spreading and not appressed to the
rachis.

[Illustration: Fig. 73.--Digitaria sanguinalis, _Var. Griffithii_.

1. Inflorescence; 2. a portion of the spike; 3 and 4. sessile and
pedicelled spikelets front and back view, respectively; 5. the
scale-like first glume; 6, 7 and 8. the second, third and the fourth
glume, respectively; 9. palea of the fourth glume; 10. the lodicules,
stamens and the ovary.]

There are four _glumes_. The _first glume_ is a minute scale. The
_second glume_ is shorter than the third and narrower, 5-nerved,
ciliate, acute or sometimes with two fine teeth. The _third glume_ is
oblong-lanceolate, acute, 5-nerved (rarely 3-nerved), ciliate on the
nerves. The _fourth glume_ is lanceolate, acute, sub-chartaceous,
paleate; _palea_ is like the glume in texture. _Anthers_ are yellow and
_stigmas_ are white. _Lodicules_ are two and small.

This seems to be a good fodder grass. It grows in all kinds of soils. It
is not so common in the plains as on the hills, though it occurs in the
plains at the base of the hills.

_Distribution._--Throughout India.

[Illustration: Fig. 74.--Digitaria sanguinalis, _Var. extensum_.]


=Digitaria sanguinalis, _Scop._=

_Var. extensum._

This grass is an annual with stems ascending from a prostrate or
geniculate, rooting branched base, greenish or purplish, glabrous and
varying in length from 1 to 2-1/2 feet.

The _leaf-sheath_ is thin, herbaceous, rather loose, keeled and
glabrous. The _ligule_ is a distinct membrane, truncate, rarely
irregularly toothed. The _nodes_ are glabrous.

The _leaf-blade_ is linear-lanceolate, acuminate, flat when mature and
convolute when young, glabrous, 1 to 12 inches long and 1/6 to 1/3 inch
broad, the margin is very closely and finely serrate, the midrib is
prominent with three or four main veins on each side.

The _inflorescence_ consists of a few or many spikes, corymbosely
arranged on a short angular slightly rough axis, erect or spreading,
1-1/2 to 4 inches long, the lowest ones in whorls of two to four; the
rachis is nearly triquetrous, laterally winged, base thickened and with
a few long white hairs; the peduncle is cylindric, smooth, 6 to 12
inches long.

[Illustration: Fig. 75.--Digitaria sanguinalis, _Var. extensum_.

1. A portion of spike; 2, 3 and 3a. the back and front views of a
spikelet; 4, 5 and 6 the first, second and the third glume,
respectively; 7. palea of the third glume; 8. anthers, lodicules and the
ovary.]

The _spikelets_ are oblong-lanceolate, acute, about 1/10 inch long,
binate, one pedicelled and the other subsessile, the pedicel is angular,
about 1/2 to 2/3 the length of the spikelet.

There are three _glumes_ in the spikelet corresponding to the second,
third and fourth glumes of a Panicum, the first glume being obsolete.
The _first glume_ is membranous, ovate-lanceolate, acute, about 1/3 the
length of the spikelet or very much less, 3-nerved, densely ciliate
along the margins and silkily hairy between the nerves. The _second
glume_ is greenish, oblong lanceolate, acute, ciliate along the margins
and with fine appressed silky hairs between the lateral nerves,
5-nerved, palea is very minute or absent. The _third glume_ is oblong,
sub-acuminate, a little shorter than the second glume, 3-nerved,
sub-chartaceous, paleate; _palea_ is similar to the glume in texture.
_Anthers_ are pale yellow with a tinge of purple. _Stigmas_ are white.
_Lodicules_ are two, minute and cuneate.

This is an excellent fodder grass and is very much liked by cattle. It
grows very rapidly and is found in cultivated fields and in somewhat
rich loamy soils.

_Distribution._--Throughout the Presidency in the plains and low hills.

[Illustration: Fig. 76.--Digitaria longiflora.]


=Digitaria longiflora, _Pers._=

This is a perennial grass with short underground branches covered with
scales. Stems are many, tufted, slender, creeping and rooting, or
ascending and suberect, simple or branched, 6 to 20 inches long and
leafy and leaves bifarious and divaricate.

_Leaf-sheaths_ are hairy or glabrous, compressed, keeled. The _ligule_
is a short membrane. _Nodes_ are glabrous.

_Leaf-blades_ are broadly lanceolate or linear-lanceolate, acute,
spreading, flat, or in short-leaved forms, stiff and pungent, 1 to 2
inches long (rarely also 5 inches long), glabrous above and below,
ciliate at the margins towards the base, and with a very minutely
serrate hyaline margin.

The _inflorescence_ consists of two to four terminal spikes with a
slender, long, hairy or glabrous peduncle. The spikes are slender, erect
or spreading with fine winged glabrous rachis.

The _spikelets_ are small, 1/20 to 1/14 inch, geminate, one short and
the other long pedicelled, appressed to the rachis, elliptic, silky with
slender crisped hairs, pale green or purplish.

[Illustration: Fig. 77.--Digitaria longiflora.

1. A portion of the spike; 2. the first glume; 3 and 4. the second and
third glumes; 5 and 6. the fourth glume and its palea; 7. lodicules,
ovary and stamens.]

There are three _glumes_ with a rudimentary first glume. The _first
glume_ is very minute and hyaline. The _second glume_ is as long as the
third, membranous, 5-nerved (rarely 3- to 7-nerved), silkily hairy. The
_third glume_ is similar to the second and usually 7-nerved (rarely 3-
to 5-nerved). The _fourth glume_ is sub-chartaceous, ovate-oblong,
paleate, slightly shorter than the third glume, pale brown, smooth.
There are two small _lodicules_. Styles are long and purple.

This grass grows in cultivated dry fields. It seems to like a sandy
loamy soil.

_Distribution._--Throughout India.



3. Eriochloa, _H. B. & K._

These are annuals or perennials. Leaves are flat. The inflorescence is a
raceme or a panicle. Spikelets are one-flowered, borne unilaterally on
the branches, and the base is thickened and jointed on the top of a
short pedicel. The spikelet has three glumes. The first and the second
glumes are subequal, membranous. The third glume is apiculate, hardened
in fruit. The lodicules are small and truncate. There are three stamens
with linear anthers. Styles are two free, with plumose stigmas. The
grain is oblong, free within the hardened glume and its palea.

[Illustration: Fig. 78.--Eriochloa polystachya.]


=Eriochloa polystachya, _H. B. & K._=

This grass is a densely tufted perennial, varying in height from 2 to 3
feet, with a short creeping root-stock. Stems are slender, or stout,
simple and branching, ascending from a short creeping and rooting base,
glabrous, slightly channelled on one side.

The _leaf-sheath_ is glabrous, green or partly purplish, striate, loose,
mouth and margins above sometimes pubescent. The _ligule_ is a short
villous ridge. _Nodes_ are perfectly glabrous.

The _leaf-blade_ is flat, linear or linear-lanceolate, acuminate,
glabrous on both sides, with a slender or prominent midrib, veins more
or less uniform, 2 to 10 inches long and 1/6 to 1/3 inch wide, convolute
when young. Sometimes the blade is purplish below.

The _inflorescence_ is a panicle on a long or short glabrous stalk,
striate, 2 to 7 inches long, with four to fifteen erect or spreading,
lax branches, the main rachis is glabrous, angular and deeply grooved.
Spikes or branches are slender, alternate, 1 to 2-1/2 inches, becoming
shorter upwards, thickened and puberulous at the base, and the secondary
rachis is flexuous, grooved, angular, and obscurely pubescent.

[Illustration: Fig. 79.--Eriochloa polystachya.

1. A portion of the branch; 2, 3 and 4. the first, second and the third
glume, respectively; 4a. back view of the third glume; 5. palea of the
third glume; 6. lodicules, stamens and the ovary; 7. grain.]

The _spikelets_ are green or purplish, ovate, lanceolate, acuminate 1/8
to 1/6 inch long, softly hairy, stalked, solitary above and binate below
and then one with a long and the other with a short pedicel rising from
a common short branchlet, loosely imbricate, distichous and shortly
stipitate and the stipe with a purple thickening; pedicel is short, 1/24
to 1/12 inch with sometimes long deciduous hairs and the tip somewhat
thickened.

There are three _glumes_ in the spikelet. The _first glume_ is
membranous, covered densely with silky hairs, ovate-lanceolate,
acuminate, tip very minutely 3-toothed with three to five fine nerves.
The _second glume_ is similar to the first glume but with a more pointed
tip, faintly 3- to 5-nerved; _palea_ is not present and if present it is
very small, hyaline and empty. The _third glume_ is shorter than the
first and the second glumes, thinly coriaceous, punctate, oblong,
obtuse, pale, faintly 3- to 5-nerved with a short scaberulous awn,
paleate; _palea_ is oblong, similar to the glume in texture, margin
infolded. _Anthers_ are three, linear, pale yellow. _Stigmas_ are
feathery, white when young and purple later. _Lodicules_ are two and
distinct.

This is a common succulent grass growing in large or small tufts in
moist situations such as sides of water channels, rivulets and bunds of
paddy fields. It is very much liked by cattle. This grass is easily
recognized by the silky lanceolate spikelets which have a purple
thickening at the base.

_Distribution._--Plains of India and Ceylon and in all hot countries.



4. Panicum, _L._

The grasses of this genus are annual or perennial and of various habits.
Inflorescence is either a raceme of spikes or, a lax or contracted
panicle. Spikelets are small, solitary or two to four, rarely more
ranked, 1- to 2-flowered, ovoid or oblong, rounded, or dorsally or
laterally compressed, falling entire with the pedicels. There are four
glumes in a spikelet. The first two glumes are empty and the first glume
is small (sometimes minute) and fewest nerved. The second glume is equal
or very nearly equal to the third glume, oblong-ovate or lanceolate, 5-
to many-nerved. The third glume is similar to the second, male or
neuter, paleate or not, 3- to 9-nerved. The fourth glume is chartaceous,
sometimes shortly stalked, ovate-oblong or lanceolate, hardened in the
fruit, smooth or rough, bisexual, paleate; the palea is as long and of
the same texture as the glume. Lodicules are cuneate or quadrate and two
in number. There are three stamens and an ovary with two style branches
ending in feathery stigmas. Grain is free and enclosed by the hardened
fourth glume and its palea.

KEY TO THE SPECIES.

  A. Inflorescence racemose of simple (rarely
  branched) spikes bearing secund spikelets.

    I. Rachis of spikes broad and flattened.

      (a) Spikelets biseriate.

            Spikelets villous.                   1. P. Isachne.

          Spikelets glabrous.

            Spikes shorter than the internodes.  2. P. flavidum.

            Spikes longer than the internodes.   3. P. fluitans.

      (b) Spikelets 3- to 5-seriate.

              Third glume awned.

            Stems stout, erect.                  4. P. Crus-galli.

            Stems stout, prostrate at base.      5. P. stagninum.

              Third glume cuspidate.

            Stems slender.                       6. P. colonum.

    II. Rachis of spikes narrow, filiform,
    terete or angular.

	First glume shorter than the third.

          First glume semilunate, about 1/4
          of the third glume.                    7. P. prostratum.

          First glume 1/2 of or less than
          1/2 of third glume, 5-nerved.          8. P. ramosum.

	Leaf base broad or cordate.

          Fourth glume shortly awned.            9. P. javanicum.

          Fourth glume muticous.                10. P. distachyum.

  B. Inflorescence a contracted or open panicle.

    I. Panicle contracted and spike-like.

          Spikelets lanceolate and first glume
          minute.                               11. P. interruptum.

    II. Panicle effuse.

          Annuals; first glume nearly 3/4 of
          the third glume.                      12. P. trypheron.

          Perennials; first glume less than
          1/3 of the third glume.               13. P. repens.

[Illustration: Fig. 80.--Panicum Isachne.]


=Panicum Isachne, _Roth._=

This is an annual grass usually growing in tufts with fine fibrous roots
and many slender spreading branches, all of them at first creeping and
horizontal, rooting at the nodes and then becoming erect and varying in
length from 1 to 2 feet.

Stems are very slender, glabrous or covered with scattered hairs,
purplish or pale green, and branching freely towards the base.

The _leaf-sheath_ is shorter than the internodes, green or purplish,
striate, externally hairy with scattered bulbous-based hairs, varying in
length from 1/2 to 3 inches, the outer margin of the sheath is ciliate
with long hairs and at the mouths sometimes long hairs are present,
especially when the leaves are young. The _ligule_ is merely a dense
fringe of long hairs. _Nodes_ are tumid, purplish, covered with long
hairs.

The _leaf-blade_ is flat but convolute when young, lanceolate or
linear-lanceolate, acuminate, base rounded and margin with minute
serrations. It is glabrous or occasionally hairy with scattered,
tubercle-based, deciduous hairs, and varying in length from 1 to 3
inches generally (sometimes in well-grown plants it is 5 inches) and in
breadth from 1/8 to 1/4 inch. The midrib is prominent though slender at
the base and four veins are present on each side with five or six
smaller ones between them.

[Illustration: Fig. 81.--Panicum Isachne.

1 and 1a. Front and back view of a spike; 2 and 2a. back and front views
of a spikelet; 3 and 4. the first and the second glume, respectively; 5
and 5a. the third glume and its palea; 6 and 6a. the fourth glume and
its palea; 7. lodicules, anthers and ovary; 8. grain.]

The _inflorescence_ is an erect, narrow panicle consisting of spikes
varying in number from 5 to 12 and in length from 2 to 3 inches. The
_spikes_ are erect, pressed to the very slender rachis, longer than the
internodes of the main rachis, stalked or sessile, mostly simple but
sometimes the lower dividing into two or three branches, 1/2 to 1 inch
long. The rachis of the spike is very slender, angular, flexuous,
narrower than the spikelets, scaberulous with a few long cilia at the
angles.

The _spikelets_ are very small, 1/16 inch long, turned all to one side
and closely packed in two rows, oblong or oval-oblong, obtuse or
subacute, softly hairy, pale green or purplish, with very short pedicels
which are pubescent with a few long hairs towards the thickened cupular
tips.

There are four _glumes_ in the spikelet. The _first glume_ is very
small, membranous, glabrous, broader than long, cordate or triangular,
broadly but shallowly emarginate, nerveless or very obscurely 1- to
2-nerved. The _second glume_ is pale or purplish, 5-nerved, hairy, as
long as the third glume, membranous, oblong and obtuse. The _third
glume_ is pale, nearly equal to the second glume with a longitudinal
depression at the back, less hairy than the second glume, 3-nerved
(rarely 5-nerved also); _palea_ is present, and it is hyaline, shorter
than the glume, truncate or shallowly retuse, usually barren but
occasionally with three stamens. The _fourth glume_ is oblong, rounded,
coriaceous, smooth, shining, dorsally flattened, 3- or indistinctly
5-nerved; _palea_ is similar to the glume in texture and with folded
margins. There are three _stamens_ with yellow anthers. _Lodicules_ are
two, very small and distinct. _Ovary_ has two styles with feathery
_stigmas_ white at first, but turning deep purple while withering.

This delicate and small grass occurs here and there as mere tufts
especially in sheltered situations. It usually flourishes in black
cotton soils amidst cholam (_Andropogon Sorghum_), although it thrives
equally well in other rich soils. This is considered to be a very good
fodder grass.

_Distribution._--It is fairly common all over the Madras Presidency, and
goes up to 3,000 or 4,000 feet. It occurs in Africa, America and Italy.

[Illustration: Fig. 82.--Panicum flavidum.]


=Panicum flavidum, _Retz._=

This plant is a tufted annual. It branches freely from the base;
branches are tufted, decumbent at first but soon becoming erect,
slender, glabrous, compressed and leafy, varying in length from 1 to 3
feet.

Leaves are somewhat distichous. The _leaf-sheath_ is compressed,
glabrous, sometimes with a tinge of purple, the lower ones swollen at
the base and the mouth is hairy. The _ligule_ is a fringe of hairs.
Nodes are glabrous.

The _leaf-blade_ is flat, thinly coriaceous, linear-lanceolate and
acuminate, or ligulate with a rounded tip, 3 to 5 inches in length, 3/16
to 5/16 inch wide, glabrous or very thinly scaberulous, base rounded or
slightly cordate with long white ciliate hairs on the small basal lobes.

[Illustration: Fig. 83.--Panicum flavidum.

1 and 2. Front and back view of a portion of spike; 1a and 2a. the front
and back view of a spikelet; 3 and 4. the first and the second glume,
respectively; 5 and 5a. the third glume and its palea; 6 and 6a. the
fourth glume and its palea; 7. anthers and ovary; 8. grain.]

The _inflorescence_ is a raceme of spikes, 5 to 10 inches long, erect or
inclined on a short or long, glabrous, strongly channelled peduncle; the
main rachis is grooved, angled and scaberulous. _Spikes_ are few or
many, 1/4 to 1 inch long, erect, pressing on the rachis of the
inflorescence along the groove, distant and sessile; the lower spikes
are very much shorter than the internodes, but the upper equal to or
longer than the internodes; the rachis of the spike is angular,
flattened below, erect or slightly recurved.

The _spikelets_ are white, in two rows on a flattened rachis, obliquely
ovoid or gibbously globose, glabrous, sessile, 1/8 inch in length.

There are four _glumes_. The _first glume_ is suborbicular, about half
the length of the third glume, usually 3-nerved. The _second glume_ is
broadly ovate, obtuse, concave, larger than the first glume and nearly
equal to or shorter than the fourth glume, 7-nerved, rarely 7- to
9-nerved, nerves are anastomosing, tip rounded. The _third glume_ is
broadly ovate or oblong, equal to or longer than the fourth glume,
obtuse, 3- to 5-nerved, paleate, mostly with and rarely without stamens.
The _anthers_ are yellow and they do not open until the stigmas and
anthers of the fourth glume are thrown out. _Lodicules_ are two and
conspicuous. _Palea_ is hyaline with infolded margins. The _fourth
glume_ is coriaceous, broadly ovate, tip acutely pointed and almost
cuspidate or acute, mucronate, white or brownish, reticulately minutely
pitted. _Anthers_ are three and yellow. _Stigmas_ are purplish.
_Lodicules_ are small but conspicuous.

This grass is very common throughout the plains and grows in the bunds
of paddy fields and in wet situations, and goes up to moderate
elevations on the hills. Cattle eat this grass greedily and seem to like
it. It is considered to be an excellent fodder.

_Distribution._--In wet situations all over India ascending to 6,000
feet. Occurs also in Ceylon, Africa, Tropical Asia and Australia.

[Illustration: Fig. 84.--Panicum fluitans.]


=Panicum fluitans, _Retz._=

This is a perennial grass with prostrate branches which afterwards
become erect towards the free ends. The young branches are covered with
scale-leaves. Stems are stout, glabrous, smooth and hollow, rooting at
the lower nodes.

The _leaf-sheath_ is loose, glabrous, striate, margins not ciliate. The
_ligule_ is a ridge with a row of erect long hairs. _Nodes_ are
glabrous.

The _leaf-blade_ is firm, linear, finely acuminate, base rounded, rather
narrower than the sheath at the white band, very thinly scaberulous
above and glabrous below, veins prominent above, 3 to 9 inches long, 1/4
to 7/16 inch broad; margins are slightly incurved and the midrib is
conspicuous only at the lower portion of the blade. The scale-leaves
persist at the base of the stems.

[Illustration: Fig. 85.--Panicum fluitans.

1 and 2. Front and back view of a spike; 1a. and 2a. front and back view
of a spikelet; 3, 4 and 5. first, second and third glume respectively;
5a. palea of the third glume and stamens in it; 6 and 6a. fourth glume
and its palea; 7. stamens and ovary.]

The _inflorescence_ is a compound spike varying in length from 4 to 10
inches, erect; the main rachis is triquetrous, dorsally rounded,
glabrous and very thinly scaberulous at the edges. _Spikes_ are many
(fifteen and more), sessile, secund, generally longer than the
internodes, and appressed to the rachis, 1/4 to 1-1/2 inches long; the
rachis of the spike is angular, edges scaberulous and with very fine
short hairs.

The _spikelets_ are pale, ovoid, acute, biseriate, imbricate, very
shortly pedicellate, glabrous, 1/16 to 1/8 inch, pedicels are hairy with
a few long hairs towards the base.

There are four _glumes_. The _first glume_ is white, thin, membranous,
truncate and wavy at the apex, nerveless or sometimes with one to three
short nerves, less than one-third of the third glume, broader than long
and clasping at the base. The _second glume_ is ovate, obtuse or
subacute, concave, submembranous, slightly shorter than the fourth
glume, 5-nerved but occasionally 6- or 7-nerved. The _third glume_ is a
little longer than the second and the fourth, usually 5-nerved, broadly
ovate, acute, paleate, always with three stamens which come out only
after the fading of the stigmas and enlargement of the ovary in the
fourth glume. _Lodicules_ are distinct and conspicuous; _palea_ is broad
with incurved broad margins and hyaline. The _fourth glume_ is thinly
coriaceous, shining, striolate, broadly ovate, mucronate, compressed,
faintly and thinly 5-nerved and _palea_ with infolded margins. _Anthers_
are yellow. _Stigmas_ are white when young. _Lodicules_ are distinct.

It is a common grass of the wet lands met with in many parts of the
Presidency and often confused and united with _Panicum punctatum_, Burm.

_Distribution._--Throughout India and Ceylon. It is also found in
Arabia, Afghanistan, Africa and Tropical America.

[Illustration: Fig. 86.--Panicum Crus-galli.]


=Panicum Crus-galli, _L._=

It is a tufted annual with many erect branches growing to a height
varying from 2 to 3 or 4 feet and the whole plant is glabrous. Stem is
stout or slender, simple or branched.

The _leaf-sheath_ is smooth, glabrous and loose, varying in length from
2 to 6 inches, keeled. The _ligule_ is only a smooth semilunar line
without hairs. _Nodes_ are glabrous and the lower nodes bear
adventitious roots.

The _leaf-blade_ is narrowly linear-lanceolate, flat, finely acuminate,
glabrous or very minutely scabrid with a stout midrib; margin is
minutely serrate and with tubercle-based hairs near the base. The blades
of the lower leaves are longer than those in the upper and at the
junction with the sheath the blade is narrow, just as broad or less than
the sheath, and becomes broader about the middle; the length varies from
6 to 10 inches generally, also to 14 inches, and breadth at base 1/4
inch and at the middle 5/16 inch; the upper leaf-blade is generally
shorter, varying from 5 to 10 inches and very broad at the base near the
sheath, about 7/16 inch and gets gradually narrow upwards. It is
convolute when young.

The _inflorescence_ is a compound spike varying in length from 4 to 8
inches, contracted and pyramidal and always erect; the main rachis is
stout, angled with very minute hairs on the ridges and with a tuft of
bristly hairs and also tubercle-based hairs at the place of insertion of
the spikes. _Spikes_ are many (up to 16 or rarely more), simple or
branched, the lower ones longer, but getting gradually shorter upwards,
and varying in length from 1/2 to 2 inches. The rachis of the spike is
angular, with scattered tubercle-based bristly hairs.

[Illustration: Fig. 87.--Panicum Crus-galli.

1 and 2. Front and back views of spike; 3. spikelet; 4 and 5. first and
second glumes; 6 and 7. third glume and its palea; 8. fourth glume,
front and back view; 9. ovary, anthers and lodicules.]

The _spikelets_ are turgid, densely packed on one side of the rachis in
three to five rows, sessile or subsessile, sub-globose or ovoid, with
unequal tubercle-based bristly hairs on the nerves of the glumes and
with short minute hairs on the outer surface of the glumes, 1/12 to 1/8
inch; awn 1/4 inch to 5/16 inch.

There are four _glumes_. The _first glume_ is 1/3 to 1/2 of the third
glume, suborbicular, abruptly acuminate or rarely mucronate and 5-nerved
(very rarely 5- to 7-nerved), clasping at base and margins thinly
ciliolate. The _second glume_ is ovate oblong, short, awned and
5-nerved; sometimes with partial nerves at the apex between the central
and the lateral nerves, and then 5- to 7- or 5- to 9-nerved, hispidly
hairy on the nerves, margins ciliolate. The _third glume_ is as long as
the second, ovate-oblong and the apex abruptly ending in a stout scabrid
nerved awn, varying in length from 1/4 to 3/8 inch, rarely 1 inch; 5- to
7-nerved (two partial at tip), paleate and sometimes with three stamens;
_palea_ is hyaline, ovate-oblong with infolded margins. The _fourth
glume_ is smooth, shining, broadly oblong, faintly 5-nerved, apex
rounded or cuspidate with a few cilia; paleate with a single bisexual
flower; _palea_ is similar to the glume in structure. _Anthers_ are
orange yellow, and _lodicules_ are very small. _Stigmas_ are white.
Grain is smooth and ovoid.

This grass grows in paddy fields and wet places generally. It is
considered to be a very good fodder grass in Australia and America. This
is the "Barn-yard" grass of the Americans, highly valued as a fodder
grass.

_Distribution._--Throughout India in wet places and in paddy fields.


=Panicum stagninum, _Retz._=

It is an annual. The stems are glabrous, creeping and somewhat prostrate
at the base, and the upper portion is erect, 3 to 4 feet long, and
rooting at the nodes in the geniculate portion of the stem.

The _leaf-sheath_ is smooth, striate, glabrous, sometimes pubescent
about the lower nodes, varying in length from 1-1/2 to 4-1/2 inches. The
_ligule_ is distinct, consisting of a fringe of stiff hairs.

The _leaf-blade_ is linear-lanceolate, acuminate or acute, base rounded,
glabrous, smooth below, especially in the lower part, and scabrid above
and in the upper part, 6 to 12 inches long, by 1/4 to 3/8 inch; the
lower leaves have their blades somewhat narrower at the base than in the
middle, but the blades in the upper part of the stem and in the middle
are of the same breadth; margins are very minutely serrate.

[Illustration: Fig. 88.--Panicum stagninum.

1. Front view of a portion of spike; 2. back view of the same; 3 and 4.
front and back views of a spikelet; 5, 6 and 7. the first, second and
the third glume, respectively; 8. palea of the third glume with its
anthers; 9. front and back view of fourth glume; 10. the ovary, stamens
and lodicules.]

The _inflorescence_ is 4 to 8 inches long; the main _rachis_ is angular,
grooved, scabrid on the ridges. The _spikes_ are 7 to 10 inches,
alternate, pale green or purplish, rather distant, spreading or suberect
(never erect) 1/2 to 1-1/2 inches long, sessile and with a tuft of
bristly hairs at the base; the rachis of the spike is angular, grooved
with scattered bulbous-based bristles on the ridges.

The _spikelets_ are four ranked, ovoid-lanceolate, 1/8 to 1/6 inch long
without the awn, somewhat flattened on one side and gibbous on the
other, pale green or purplish, with equal bulbous-based bristly hairs on
the nerves.

There are four _glumes_. The _first glume_ is half of the third glume,
thin, membranous, hairy, broadly ovate, abruptly cuspidate at the apex,
and acuminate, 5-nerved (rarely 3-nerved). The _second glume_ is broadly
ovate-lanceolate, concave, acuminate, short awned, 5-nerved with two
partial nerves one on each side of the central nerve (7- to 9-nerved at
the tip), hairs on nerves, a few tubercled. The _third glume_ is similar
to the second, broadly ovate-lanceolate, awned, awn 1/8 to 1/4 inch,
paleate with usually three stamens, occasionally neuter. _Lodicules_ are
present. The _fourth glume_ is chartaceous, shining, smooth
ovate-oblong, apex cuspidate, with a few hairs on the edges at the apex,
faintly 5-nerved. The _anthers_ within this glume come out before those
of the third glume. _Anthers_ are three, yellowish and _lodicules_ are
conspicuous though small.

In this grass very often, purple streaks or bands occur across the leaf
blades and the sheath and the spikelets become purple on one side as is
met with in P. colonum. This grass is occasionally found in the paddy
fields either alone, or along with _Panicum Crus-galli_.

_Distribution._--Throughout the Madras and the Bombay Presidencies and
in Ceylon in wet places especially in cultivated ground and in ditches.
Occurs more or less throughout India.

[Illustration: Fig. 89.--Panicum colonum.]


=Panicum colonum, _L._=

This is a slender annual growing to a height of 2 feet. The stems are
creeping below, erect above, and with roots in the lower internodes of
the decumbent part of the stem, smooth, dull green or partly purplish.

The _leaf-sheath_ is glabrous and sharply keeled. The _nodes_ are
glabrous or obscurely pubescent. There is no _ligule_.

The _leaf-blade_ is narrow, lanceolate, acuminate, glabrous but
sometimes tubercle-based hairs occur just on the margin at the base of
the leaf-blade close to the white band, varying in length from 1 to 6
inches and in breadth 3/16 to 5/16 inch; the margin is minutely and
distantly serrate, midrib is quite distinct and there are three main
veins on each side and three or four smaller between main ones. The
blades of the lower leaves are narrow at the base and broader at about
the middle but those of the upper are equally broad at the base, as well
as at the middle.

[Illustration: Fig. 90.--Panicum colonum.

1 and 2. The front and back view of the spikes; 1a and 2a. the back and
the front view of the spikelet; 3, 4 and 5. the first, second and the
third glume, respectively; 6. palea of the third glume; 7 and 8. the
fourth glume and its palea; 9. ovary anther and lodicules.]

The _inflorescence_ is a contracted panicle, 3 to 5 inches long.
_Spikes_ are from 8 to 20, suberect, usually distant, 1/4 to 1 inch long
and getting shorter upwards; the rachis of the spike is stout, angular,
scaberulous on the angles with a few long hairs towards the base.

The _spikelets_ are small green or partly purplish 1/12 to 1/10 inch
long, globosely ovoid, acute, pubescent with minute hairs on the outer
surface of the glumes and bristly hairs on the nerves, all on one side,
sessile or very shortly pedicelled, two or three from a node, one or two
barren, 3- to 5-seriate.

There are four _glumes_ in the spikelet. The _first glume_ is about half
of the third glume, broadly ovate or suborbicular, acute, generally
3-nerved, rarely 5-nerved, pubescent between and hispidly hairy on the
nerves. The _second glume_ is as long as the third, broadly ovate,
cuspidate, 5-nerved sometimes with two partial nerves added one on each
side of the central vein, pubescent between the veins and hispid on the
veins. The _third glume_ is similar to the second, 5-nerved, tip with a
few cilia, paleate; _palea_ is empty oblong-orbicular, subacute. The
_fourth glume_ is coriaceous, shining, turgid, broadly ovate, acute,
paleate. Sometimes the tip possesses a few cilia. _Anthers_ are three,
pale yellow and _stigmas_ dark purple. _Lodicules_ are small but
conspicuous.

This grass is common in water-logged situations, in paddy fields and in
irrigated dry lands. Sometimes on the blades of this grass purple bands
are present and the internodes and the spikes also become purplish.

It is really a weed of cultivation met with generally on rich soils.
This grass is considered to be one of the best fodder grasses in India.
All kinds of cattle eat it greedily.

_Distribution._--It is found throughout India up to 6,000 feet and also
in all warm countries.

[Illustration: Fig. 91.--Panicum prostratum.]


=Panicum prostratum, _Lamk._=

The plant is a slender annual and it consists of several branches,
prostrate and creeping, with adventitious roots at the nodes below,
branching or ascending above, all green or sometimes purple above and
green below, 4 to 18 inches long.

The _leaf-sheath_ is striate, 1 to 2 inches long, glabrous or very
sparsely hairy, purplish above and green below or all green, keeled,
margins ciliate on one side only throughout its length. The _ligule_ is
a fringe of white hairs. The _nodes_ are glabrous or pubescent.

The _leaf-blade_ is short or long, varying from 1/2 to 2-1/2 inches in
length and 3/16 to 5/16 inch in breadth, convolute when young,
lanceolate to broadly ovate-lanceolate, acute or acuminate, upper
surface glabrous, and the lower glabrous or with a few scattered
tubercle-based hairs; margins are very minutely serrate; base is
cordate, amplexicaul with a few long slender hairs (sometimes
tubercle-based), just close to the white patch on both sides on the
margin of the blade about the ligule. The midrib is distinct.

The _inflorescence_ consists of five to fifteen or twenty spikes
spreading in all directions, distant or crowded; peduncle varies from 1
to 4 inches. _Spikes_ are 1/2 to 1-3/8 inches, sessile or shortly
stalked; the _rachis_ of the spike is slender, trigonous and
scaberulous.

[Illustration: Fig. 92.--Panicum prostratum.

A. Front and back view of spike; B. front and back view of a spikelet;
1, 2, 3 and 4, the first, second, third and the fourth glume,
respectively; 3a and 4a. the palea of the third and the fourth glumes;
5. anthers, ovary and lodicules.]

The _spikelets_ are crowded all on one side, 2- to 3-seriate,
ellipsoidal, 1/20 to 1/16 inch long, glabrous or pubescent, pale green
or purple on one side, in pairs on pedicels, one with a slightly longer
pedicel than the other; fine long hairs, varying in number from one to
eight and longer than the spikelets, are found on the pedicels at their
tips in some plants and not in others.

There are four _glumes_ in the spikelet. The _first glume_ is very short
about 1/4 of the third or less, semilunar, membranous, hyaline,
subtruncate, obtuse or acute, generally nerveless, but rarely, obscurely
1- to 3-nerved. The _second glume_ is membranous, ovate, acute, glabrous
or pubescent and 7-nerved. The _third glume_ is of about the same length
as the second, 5-nerved, always paleate, with or without stamens;
_palea_ is broad, margins infolded, 2-nerved, obtuse and hyaline; when
stamens are present the _lodicules_ are very conspicuous. The _fourth
glume_ is slightly shorter than the third, oblong or elliptic,
apiculate, minutely rugulose, thinly coriaceous, with bisexual flower;
_palea_ is similar to the glume in texture and markings. _Stamens_ are
three with yellowish anthers. _Lodicules_ are small and fleshy.

This plant occurs widely as a weed of cultivation in black cotton as
well as other kinds of soil and shows variation in its leaves and
spikelets. In some plants growing in somewhat dry places the leaves are
shorter and broader, and those in favourable situations have longer
narrower leaves. The spikelets are either perfectly glabrous or
pubescent and long hairs may or may not be present on the pedicels. As
regards colour the whole plant is green or the exposed portions of stems
and spikelets are purplish. This grass is liked by cattle and is one of
the most nutritious of Indian fodder grasses.

_Distribution._--Throughout India and Ceylon in the plains. Common in
the Tropics.

[Illustration: Fig. 93.--Panicum javanicum]


=Panicum javanicum, _Poir._=

This is an annual and it branches freely and the branches are decumbent
and rooting at the nodes at the base, and erect to some extent at the
free end, 1 to 2 feet long; the internodes are glabrous, thinly striate,
shallowly channelled on one side.

The _leaf-sheath_ is somewhat compressed and loose, covered with
scattered long hairs, some of them being tubercle-based; the margin is
ciliate on one side only. The _nodes_ are pubescent with long hairs. The
_ligule_ is a distinct fringe of hairs.

The _leaf-blade_ is broadly lanceolate, cordate at base, amplexicaul,
acuminate or acute, with scattered long hairs both above and below, and
some of the hairs of the under surface are tubercle-based, convolute
when young; margin of the leaf is wavy, minutely serrate, and ciliated
with distant hairs towards the lower half of the leaf when young; the
midrib is prominent below.

[Illustration: Fig. 94.--Panicum javanicum.

1 and 2. Front and back view of a spike; 3, 4, 5 and 6. the first,
second, third and the fourth glume, respectively; 5a and 6a. the palea
of third and fourth glumes; 7. the ovary and the stamens.]

The _inflorescence_ is a panicle of spikes on a short or long erect
slender peduncle. _Spikes_ vary from two to ten in number and in length
from 1/2 to 2 inches, distant and spreading; the rachis of the spike is
zigzag, somewhat flattened with a wavy ridge, scaberulous or glabrous,
swollen towards the base and the swollen part is pubescent.

The _spikelets_ are biseriate, loosely imbricate, ovate, acute,
pubescent or villous (sometimes quite glabrous), sessile or shortly
pedicelled; the pedicels have one or two (rarely more) long hairs.

There are four _glumes_. The _first glume_ is small, membranous, less
than 1/2 of the third glume, ovate, acute or obtuse, 3- to 5-nerved. The
_second glume_ is nearly equal to the third, ovate acute, generally
7-nerved and sometimes 7- to 13-nerved. The _third glume_ is similar to
the second in shape, generally 5-nerved and occasionally 7-nerved,
paleate with three stamens or empty; _palea_ 2-nerved, ovate or oblong,
margins infolded. The _fourth glume_ is ovate or oblong, rugulose,
chartaceous, apex with a distinct mucro concealed in the second and
third glumes; _palea_ same as the glume in texture, etc. _Anthers_ are
yellowish; _stigmas_ are feathery and purple in colour; _lodicules_ are
small and fleshy.

This is an excellent fodder grass. Though it is an annual it grows
rapidly under favourable conditions. A single plant found growing in the
compound of the Agricultural College, Coimbatore, weighed 15 lb. and
occupied 15 square feet of the ground. It flourishes in cultivated dry
fields and in rich loamy soils. (See fig. 7.)

_Distribution._--Plains of India and Ceylon and in Tropical countries
generally.

[Illustration: Fig. 95.--Panicum ramosum.]


=Panicum ramosum, _L._=

This is an annual with stems erect or ascending from a creeping base,
rooting at the lower nodes, 1 to 2 feet long. The stem is slender or
stout, usually glabrous though occasionally glabrescent or pubescent,
channelled on one side, branched from base upwards, and leafy.

The _leaf-sheath_ is finely striate, keeled, thinly pubescent with the
margins ciliate near the ligule. The _ligule_ is only a fringe of short
hairs. _Nodes_ are softly hairy.

The _leaf-blade_ is flat, linear-lanceolate, acuminate, softly pubescent
or glabrescent on both the surfaces, with rounded or subcordate base and
margins minutely serrate and ciliate, 2 to 6 inches long 1/6 to 1/2 inch
broad; the midrib is distinct though slender with four to six main veins
on each side.

The _inflorescence_ is a pyramidal panicle 2 to 6 inches long,
consisting of usually five to ten (rarely also up to twenty) erect or
spreading spikes. _Spikes_ are distant, alternate and in some the lower
ones are opposite, 1/2 to 2-1/2 inches long or shorter. The _rachis_ of
the spike is thin, angular and scaberulous.

The _spikelets_ are usually pubescent, ovoid or obovoid, acute, turgid,
1/8 inch, pale green and some occasionally purplish on one side,
alternate close or distant, in pairs lower down and then one with a
somewhat longer pedicel, solitary in the upper portions, pedicels with
hairs, some of them especially those near the apex being longer.

[Illustration: Fig. 96.--Panicum ramosum.

1 and 2. Back and front view of spike; 3 and 4. front and back view of a
spikelet; 5 and 6. first and second glumes; 7 and 8. third glume and its
palea; 9 and 10. fourth glume and its palea; 11. ovary, anthers and
lodicules.]

There are four _glumes_. The _first glume_ is nearly half the length of
the third glume, broadly ovate, subacute, margin overlapping at the
base, and usually 5-nerved. The _second glume_ is broadly ovate acute,
rather cuspidate, usually 5-nerved (rarely 7-nerved). The _third glume_
is similar to the second glume, 5-nerved, paleate, empty; _palea_ is
hyaline oblong, acute. The _fourth glume_ is ovoid-oblong, acute,
coriaceous, rugulose, w