The Romance of Plant Life

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.

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 Melocactus81 and others.

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.82 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.83

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."84 In frost and snow almost every plant is attacked by rabbits, and indeed by any grazing animal.

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."85 The brambles and briers of Gilead and Ezekiel were probably brambles of which Rubus discolor is common in Palestine,86 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.87

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.88

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 plant89 (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.

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."90 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.

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,91 takes up this question. It is best to give the description in his own words: —

"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."92

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.93

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 Marilaun94 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!

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 Henslow95 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.

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.96

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.