ON VEGETABLE DEMONS
Animals and grass--Travellers in the elephant grass--Enemies
in Britain--Cactus _versus_ rats and wild asses--Angora
kids _v._ acacia--The Wait-a-bit thorn--Palm roots and
snails--Wild yam _v._ pig--Larch _v._ goat--Portuguese and
English gorse--Hawthorn _v._ rabbits--Briers, brambles,
and barberry--The bramble loop and sick children or ailing
cows--Briers of the wilderness--Theophrastus and Phrygian
goats--Carline near the Pyramids--Calthrops--Tragacanth--Hollies
and their ingenious contrivances--How thorns and spines are
formed--Tastes of animals.
By far the greater number of wild animals live by eating vegetables.
If one thinks of the elephant's trunk, the teeth of a hippopotamus,
or even of the jaws and lips of mice, rats, and voles, the thoroughly
practical character and efficiency of their weapons become the more
astonishing the more one reflects upon them.
Yet the defences adopted by plants are just as wonderful, and are
often most ingenious.
It seems at first remarkable that the most usual food of animals,
grass, should be apparently unprotected. It is upon grass that the
great herds of bison, of buffalo, of antelope, and guanaco, are or
were supported. Yet grass is so wonderfully reproductive, produces
such enormous quantities of buds and foliage, and grows in such
luxuriance, that there is no fear of its being killed out.
There are many places in the world where vegetation defies the
attacks of the animal world. Neither man nor elephant can live
comfortably in the thick jungles of West Africa and the great forests
of Brazil. Nor can either man or elephant utilize great tracts of
country in Central Africa which are covered by the Elephant Grass.
For, perhaps, four or five hours the weary caravan plods on through a
sort of burrow, two feet wide, made in this gigantic grass. The stems
are ten feet or more in height, and nearly meet overhead. There is
nothing whatever to be seen except the narrow path. The atmosphere is
stifling and hot. To cut a new road a few hundred yards long through
it involves hours of labour. It is only when there has been a long
drought that it is possible to set fire to the Elephant Grass, and
then for a very short time the young growing shoots can be grazed.
But no cattle can break through when it is fully grown.
The very exuberance of vegetation in such cases prevents any harm.
Perhaps it is best to show how, even in Great Britain, all plants
have many dangerous foes. The roots of trees are nibbled by mice,
voles, and sometimes by swine. The bark is injured by cattle,
roedeer, reddeer, fallowdeer, who tear the bark with their horns,
and especially by rabbits and hares. The leaves are eaten by the
same animals and also by horses, goats, sheep, etc. The young buds
are attacked by squirrels, who also break off the leading shoots of
certain firs when they happen to be in a playful mood.
But it is in cultivated lands and in open, rather dry and arid
country that one finds the most interesting weapons in the fights
between plant and animal. It is in such places that some of the most
beautiful and useful creatures have their home. The horse, ass,
camel, goat, and sheep probably belong to those wonderful lands
which border the great deserts of Africa and Asia. These animals have
been obliged to travel far and fast, and to perfect their bodily
strength in order to pick up a living.
[Illustration: _Stereo Copyright, Underwood & Underwood_
_London and New York_
CULTIVATED BAMBOO IN A CHINESE PLANTATION
These giant grasses are sometimes one hundred and twenty feet
high and one foot in diameter. They at times grow at the rate of
three feet per day, and are used for all sorts of purposes, such
as scaffolding poles, flower-pots, as a vegetable, etc. etc.]
They have been taught (perhaps we should say learnt) by the thorns
and briers of the wilderness.
The Cactus, Prickly Pears, or other succulent plants which belong
to true deserts, are covered over with most curious and interesting
spines. A row of little projections runs down each edge of the
round fleshy stem. On each projection there is a rosette of spines.
Sometimes these are long, slender, and diverging; in other cases they
are short, stout, and curving over.
Now imagine a guanaco in South America, or even a rat or mouse, which
is perishing of thirst in the arid desert where such things are
found. It will be seen that it is by no means easy for it to taste
the water in the juicy stem, for even the thin muzzle of a rat could
scarcely get between the thorns.
Kerner describes how the wild asses in South America root up or try
to split the Cacti with their hoofs to get at the juicy tissue of the
unarmed lower parts. Yet they often receive dangerous wounds in doing
so from the frightful spines of Melocactus[80] and others.
[80] Kerner, _l.c._, vol. I, p. 447.
It is very interesting to see a flock of Angora goats in South Africa
attacking an Acacia. The kid is a pretty, white, fluffy little
creature, with the most meek, mild, and innocent expression. Yet it
is a quarrelsome little brute. In a few minutes an Acacia will be
despoiled, broken, and robbed of its foliage by a flock of them,
although it bristles all over with long spines, of which there are a
pair at the base of each leaf.
Even the _Kameeldorn_, Camelthorn Acacia, or the Wait-a-bit in South
Africa cannot defend itself.
The Wait-a-bit (_Wacht een beetje_) is so called from the ingenious
nature of its spines. There are two together, of which one is
straight and the other curved round like a hook. Both are very sharp
and strong, so that an incautious traveller is sure to injure himself
and his clothes. The straight one runs into his tender flesh, whilst
the curved one fixes itself in his clothes.
It is by thorns, spines, and prickles that plants often protect
themselves against the attacks of grazing animals. But it must be
remembered that these are by no means the only safeguard. Plants
produce poisonous, bitter, or strong-smelling substances which keep
off their enemies, and these indeed often afford a more efficient
protection (see Chap. III.). These thorns, etc., can be produced in
the most unexpected places. There is one rule, however, namely that
they are invariably found in the exact spot where they can be most
useful.
Thus there are certain palms which possess green, juicy leaves,
much relished by snails. These are protected by a sort of spine
entanglement formed upon certain roots, which grow at the base of
the leaves. Nor is this the only case in which spines are found on
roots. There are certain South African bulbs (_Moræa_) which are
protected from the wild pigs by a dense mass of spiny roots.[81] On
my march to Uganda from Mombasa, I was very much astonished to see an
extraordinary Wild Yam. It had a huge underground tuberous part full
of starchy matter, but it was quite impossible for any marauding wild
boar to get at it, for it was entirely enclosed in a sort of arbour
of long, arching roots densely covered by stout spines, which made a
perfect protection.[82]
[81] Scott, _Annals of Botany_, vol. 11, p. 327.
[82] Scott Elliot, _Naturalist in Mid Africa_.
It is more usual to find thorns developed on the branches or stems.
Generally these are formed on the outside towards the end of the
branches. In the Alps, larches have to suffer from the attacks of
goats which nibble off the ends of the young shoots. The part behind
the scar dries up, but fresh twigs are put out from further back
along the branch, until the tree becomes a closely branched, twiggy,
bristling mass which looks like the clipped yews in old gardens. But
so soon as it has grown tall enough to be above the reach of the
goats, an ordinary larch stem develops and may grow into quite a
respectable tree. This fact is given by Kerner von Marilaun (_l.c._,
p. 445), and is very instructive, as explaining why it is that so
often the ends of the branches become hard thorns: the green leaves
and twigs are hidden and protected.
One of the neatest examples of this is the Portuguese Gorse or Whin,
which resembles a little cushion with every branch ending in strong
thorns and every leaf terminated by a stout spine.
The common Whin, Furze, or Gorse, is very nearly as perfect an
example of thorniness and spininess. The Southdown sheep do not seem
to injure it on those beautiful Sussex downs so famous for succulent
mutton, yet in the early spring, or in a very wet season, one often
finds in the grass at the foot of the bush (or even in the bush
itself) small shoots which would be taken at first sight as belonging
to some other plant. These little shoots are grey with hairs and have
soft trefoil leaves which are quite unprotected, for their spines are
quite soft. They are probably seldom eaten, for most of them are in
the shelter of the old spiny bushes.
Yet even the old bushes can be used as fodder for sheep if they are
crushed and ground up so as to break the thorns and spines. The Gorse
is a very hardy plant, and is said to be only out of flower "when
kissing is out of fashion" (see p. 100).
There is still some uncertainty as to the exact way in which animals
set to work when they are eating thorny or spiny bushes. This makes
the arrangement of the thorns sometimes a little difficult to follow.
Moreover it is often not so much the leaves as the juicy bark in
winter and early spring that is required. Sometimes everything above
ground is eaten down.
Rabbits, for instance, do not as a rule touch the Hawthorn, yet Mr.
Hamilton says, "The second winter after planting was very severe and
this hedge was eaten down to the very ground by rabbits. For about
600 yards I do not think that a single plant was missed."[83] In
frost and snow almost every plant is attacked by rabbits, and indeed
by any grazing animal.
[83] Mr. Thomas Hamilton, _Researches by Lanarkshire Teachers_,
1902-3.
Remembering that it is very often the young juicy shoots that are
sought after, it is quite easy to see why the young Rose suckers and
shoots from the base of the stem fairly bristle with long and short
prickles. These latter are generally straight, not curved like those
of the long arching branches which are supposed to hook themselves
on the branches of the surrounding trees. The young light-coloured
branches of the cultivated Gooseberry are flexible, and hang over in
such a way as to make it difficult for an animal to reach the bark: a
cow or sheep, if it wished to eat these branches, would begin at the
hanging tip and make a sort of upward tearing jerk while its tongue
gathered the branch into its mouth. If one copies this with the hand
it is easy to see how the length and arrangement of the prickles and
the flexible nature of the spray would make such a proceeding on the
cow's part most uncomfortable.
So also in the Barberry, the young juicy upright shoots which spring
from the older branches have stout three to seven-branched prongs
pointing downwards, of the most efficient character. Each is really
a modified leaf and is found below each bud. Even the mere idea of
an animal's tender lips or tongue tearing at these shoots from below
gives one a momentary shudder. In the younger, wavy branches of the
Barberry the spines are straighter or more diverging. The young
leaves of the short bud above alluded to are also most efficiently
protected by their spines. The Hawthorn has a curious arrangement of
very long stout thorns, behind which the leaves are sheltered. The
younger flexible branches have smaller spines, which become efficient
in winter and tend to prevent animals from eating the bark. The
Cockspur thorns are 4 to 5-1/2 inches long, and extremely like the
spur of a gamecock.
Bramble prickles are generally curved back in order to hook or cling
to the branches of other trees, but any one who has tried to force
his way through a clump of brambles knows the difficulty of doing so.
The loops made by the branches fixing themselves in the ground (see
p. 93) were at one time given credit for healing various diseases.
Children in Gloucestershire used to be dragged backwards and forwards
under these loops; in Cornwall also people afflicted with boils were
made to crawl under them. Even cows when suffering from paralysis
(supposed to be due to a shrew-mouse walking over them) were dragged
through the Bramble-loop, in which case Professor Buckman remarks,
"If the creature could wait the time of finding a loop large enough
and suffer the dragging process at the end, we should say the case
would not be so hopeless as that of our friend's fat pig, who, when
she was ailing, had a mind to kill her to make sure on her."[84] The
brambles and briers of Gilead and Ezekiel were probably brambles of
which _Rubus discolor_ is common in Palestine,[85] and the Butcher's
Broom (_Ruscus aculeatus_). This last plant is really of the Lily
family, and its flat leaf-like branches end in a sharp spine. The
rabbit does not eat it.[86]
[84] Lindley's _Treasury of Botany_.
[85] Ridley, _Pharmac. Journ._, May 19, 1900.
[86] Maxwell, _Memories of the Months_, First Series, 1, pp.
74-76.
Amongst foreign thorny and spiny plants it is very difficult to make
a selection.
Theophrastus (one of the very earliest botanists--see p. 37)
describes a class of shrub very common in Phrygia, in which the
leaves are produced at the base of the young shoots, which latter end
at the top in branch thorns. These thorns, therefore, entirely cover
the foliage and keep off that vegetable demon the goat. Some of the
Crucifers, Roses, Composites, Labiates, etc., take on this habit in
goat-infested countries.[87]
[87] Kerner, _l.c._
In Egypt, near the Pyramids, one often finds _Carlina acaulis_, a
little thistle which has no stem, but is merely a flower seated in
the middle of a rosette of leaves which lie flat on the sand. In the
centre there is a circle of sharp spines, each of which is from one
to two inches in length. The nostril of a hungry camel or donkey is
sure to be pierced if it tries to eat the leaves. The spines of this
thistle, like those of our Carline and the _Centaurea calcitrapa_
(thistle of the Bible), spring from the bracts surrounding the
flower.
The ancient "calthrops" or "crawtaes" (first used by the Romans) were
designed from the spines of the last-named plant[88] (_calx_, heel,
and _trappa_, snare.) It had four iron spines, so that, however it
was thrown down on the ground or in a ford, a spine was sure to stick
up and to lame man or horse.
[88] Ridley _l.c._
[Illustration: 1. Old Roman Calthrops, left on roads, fords,
etc., to lame horses.
2, 3. Fruits of Tribulus, showing efficient spines. Animals'
feet, in passing, must catch them. They are more efficient than
Calthrops.]
The Tragacanth plant has also very neat spines. They are the
persistent spiny stalks or midribs of the older leaves from which
the leaflets have dropped away. The fresh green leaflets are quite
protected inside these withered spines.
Several grasses have leaves which end in sharp or needlelike points.
One of these, _Festuca alpestris_, actually produces bleeding at the
nostrils of grazing cattle, and is detested by all the shepherds of
the Alps.
The Holly is one of our most beautiful trees, as John Evelyn points
out: "This _vulgar_ but _incomparable_ tree.... Is there under
_Heaven_ a more glorious and refreshing object of the kind than
an impregnable _hedge_ of near _three hundred_ feet in _length_,
_nine_ foot _high_ and _five_ in _diameter_: which I can show in my
poor _Gardens_ at any time in the year, glittering with its arm'd
and vernished _leaves_? The taller _Standards_ at orderly distances
blushing with their natural _Coral_."[89] This apparently was the
identical hedge into which Peter the Great used to trundle his
wheelbarrows. The barrows contained his courtiers. There was a nice
run from the top of rising ground close at hand. It was at Sales
Court, Deptford.
[89] Evelyn, _Silva_.
The spiny leaves of the Holly are unfortunately not nearly strong
enough to save it from its enemies. The bark is apparently of a
particularly delicious and toothsome nature, for sheep, cattle, and
the ubiquitous rabbit are always delighted to destroy the trees.
It has been noticed that wild hollies have at the base very spiny
leaves, but that higher up on the tree (above the reach of cattle)
the leaves have no spines at all. Sir Herbert Maxwell, in his
_Memories of the Months_,[90] takes up this question. It is best to
give the description in his own words:--
[90] Third Series, p. 60.
"I strolled out along the banks of Tay in that noble woodland which
is continuous from Dunkeld to Murthly. Here there are many fine
hollies, some on the river banks and cliffs, others on level ground,
planted by no hand of man. There was not one of these which did
not confirm my observations first made many years ago, and hardly
one which did not bear evidence of special growth--not merely as a
reaction against pruning or cropping, but _as a precaution_ _against
any such contingency_--so regular and deliberate as to suggest that
these trees are something more than unconscious automata.
"Many of these hollies are thirty feet high, with foliage down to
the ground. They carry spinous leaves up to a height of three or
four feet; above that level all the foliage is absolutely smooth
and spineless. One tree rose from the ground in two bare stems, and
the lower branches did not reach below the browsing level. But from
between the two old stems rose a young shoot about four feet long,
clothed throughout its entire length with intensely prickly leaves.
This tree was growing in an enclosed wood where cattle could not
come; still, roedeer might be about, and the holly armed its young
growth at the low level, although the leaders of the old stems, not
less vigorous in growth, bore leaves as smooth as a camellia's. I
noted one particularly suggestive tree, an unhealthy one. The growth
had died back along most of the branches, which stood out bare and
dry; but a recuperative effort was in progress; fresh and luxuriant
growth was bursting along nearly the whole height of the stem, and
the foliage of this was vigorously prickly up to about four feet,
and smooth above that height. I noticed many instances of localised
prickly growth where boughs, originally above the browsing level,
and clothed with spineless leaves, had been weighed down and cropped
by cattle. But this is merely a vigorous reaction against external
injury, such as makes a clipped holly hedge bear spinous foliage from
base to summit."[91]
[91] _Memories of the Months_, Third Series, p. 366.
This quotation shows that there is no doubt as to the facts. It is
true that one finds cultivated hollies showing many variations.
Sometimes all the leaves are spiny, both above and below. In other
varieties none of the leaves possess spines at all. Yet it must be
admitted that these are facts and cannot be denied.[92]
[92] I had expressed some doubt in my _Nature Studies: Plant
Life_.
Moreover, the Osmanthus, with its holly-like leaves, the Evergreen
Oak, and some Junipers are found to show exactly the same curious
difference. The perilously-situated lower leaves are more spiny than
those which are above the reach of grazing animals.
Kerner von Marilaun[93] also has remarked a similar protective
arrangement in _Gleditschia chinensis_ and in the Wild Pear. Trees
of the latter, when they are young, "bristle with the spines into
which the ends of the woody branches are transformed"; but tall trees
twelve to fifteen feet high are entirely without thorns!
[93] _l.c._, vol. I, p. 433.
It is when one meets coincidences of this nature that the full
meaning of plant life begins to dawn upon the mind.
How is it that the plant knows the time to produce its spines, and
the time to refrain from doing so?
There are certain queer facts that have been given on good authority
as to the causes which tend to produce thorniness and spininess.
Linnæus, _Philos. Bot._, p. 215, § 272, says:--
"Spinosae arbores cultura saepius deponunt spinas in hortis."
Lothelier found that Barberries grown in a moist atmosphere had no
spiny leaves, and that the thorns were far less woody under those
conditions, whilst in a perfectly arid and dry atmosphere only spines
were formed; a strong light also tended to produce spines.
Professor Sickenberger grew a desert plant (_Zilla myagroides_) in
the Botanic Garden at Cairo, and found that its spines were much
weaker and more slender than the strong rigid thorns which cover it
in its natural desert.
Professor Henslow[94] found that the spiny form of the Rest Harrow,
when grown in a rich soil with an abundance of water, gradually loses
its spines. All these experiments certainly show that a dry desert
sort of life, and possibly strong sunlight, favour the development of
spines and thorns.
[94] _Origin of Plant Structures_, pp. 38-40.
Of this there cannot be any reasonable doubt, for the extraordinary
quantity of thorny, spiny things in deserts shows that there must be
some connexion between such a life and their production (see Chapter
X.). In such places animals are always abundant. But these hollies,
pears, and other plants show exactly the opposite to what we should
expect. It is when the head of the young holly reaches the sunlight
and feels the wind that its leaves become harmless!
If one remembers the case of the young larch and its goat enemies on
page 181, it is perhaps possible to think that the lower branches
and twigs were for untold generations exposed to laceration and
biting. Thus, suffering from the loss of water by these regular
annual wounds, the leaves developed their spines in response. So far,
belief is not more difficult than it is with regard to the origin
of any variety. But whenever, by reversion to their ancestral type,
the original not-spiny leaves developed on the top of a tree, that
tree would have an advantage, for every leaf on it would be more
economically produced; a smooth leaf would not require to spend food
in order to make spines. Such trees, spiny below and smooth above,
would be best fitted to survive, healthier and more vigorous, and in
the end would leave more descendants.
At the same time, such a case as this reveals again that mysterious
and exquisite purposefulness which a reverent mind discovers in
Nature everywhere.
At the same time, as we have already pointed out, we are exceedingly
ignorant of many of the very commonest facts. Léo Errera, the great
Belgian botanist (whose recent death has been a terrible loss to
science), collected together some facts as to the taste of cattle for
various spiny and thorny plants; he found that cattle wished to eat
the following: Buckthorn, whin or gorse, raspberry, brambles, the
Scotch thistle, the creeping thistle, as well as musk, welted and
slender thistles, sow thistle, and saltwort.
They avoided: Barberry, the petty and German whin, rest harrow, the
carline, and the other thistles not given above, as well as the
common juniper.
They disdained or despised: Sea holly, common holly, milk thistle,
_Lactuca_, and _Urtica urens_.[95]
[95] Errera, _Un Ordre de Recherches trop négligé_. See also
Ludwig, _Biologie d. Pflanzen_, p. 210.
So far as the holly is concerned, it is certainly not despised
by sheep and rabbits in this country. But how few are the plants
investigated! Several of the commonest British plants are omitted
just because no one has taken the trouble to watch them.
Here, then, is an opportunity of discovering something new, fresh,
and interesting which should be well within the reach of any one who
passes his life in the country.