Chapter VII: The Stem

§ 1. We must be content, in this most complex subject, to advance very slowly: and our easiest, if not our only way, will be to examine, first, the conditions under which boughs would form, supposing them all to divide in one plane, as your hand divides when you lay it flat on the table, with the fingers as wide apart as you can. And then we will deduce the laws of ramification which follow on the real structure of branches, which truly divide, not in one plane, but as your fingers separate if you hold a large round ball with them.

The reader has, I hope, a clear idea by this time of the main principle of tree-growth; namely, that the increase is by addition, or superimposition, not extension. A branch does not stretch itself out as a leech stretches its body. But it receives additions at its extremity, and proportional additions to its thickness. For although the actual living shoot, or growing point, of any year, lengthens itself gradually until it reaches its terminal bud, after that bud is formed, its length is fixed. It is thenceforth one joint of the tree, like the joint of a pillar, on which other joints of marble may be laid to elongate the pillar, but which will not itself stretch. A tree is thus truly edified, or built, like a house.

§ 2. I am not sure with what absolute stringency this law is observed, or what slight lengthening of substance may be traceable by close measurement among inferior branches. For practical purposes, we may assume that the law is final, and that if we represent the state of a plant, or extremity of branch, in any given year under the simplest possible type, Fig. 44, _a_, of two shoots, with terminal buds, springing from one stem, its growth next year may be expressed by the type, Fig. 44, _b_, in which, the original stems not changing or increasing, the terminal buds have built up each another story of plant, or repetition of the original form; and, in order to support this new edifice, have sent down roots all the way to the ground, so as to enclose and thicken the inferior stem.

But if this is so, how does the original stem, which never lengthens, ever become the tall trunk of a tree? The arrangement just stated provides very satisfactorily for making it stout, but not for making it tall. If the ramification proceeds in this way, the tree must assuredly become a round compact ball of short sticks, attached to the ground by a very stout, almost invisible, stem, like a puff-ball.

For if we take the form above, on a small scale, merely to see what comes of it, and carry its branching three steps farther, we get the successive conditions in Fig. 45, of which the last comes already round to the ground.

"But those forms really look something like trees!" Yes, if they were on a large scale. But each of the little shoots is only six or seven inches long; the whole cluster would but be three or four feet over, and touches the ground already at its extremity. It would enlarge if it went on growing, but never rise from the ground.

§ 3. This is an interesting question: one, also, which, I fear, we must solve, so far as yet it can be solved, with little help. Perhaps nothing is more curious in the history of human mind than the way in which the science of botany has become oppressed by nomenclature. Here is perhaps the first question which an intelligent child would think of asking about a tree: "Mamma, how does it make its trunk?" and you may open one botanical work after another, and good ones too, and by sensible men,--you shall not find this child's question fairly put, much less fairly answered. You will be told gravely that a stem has received many names, such as _culmus_, _stipes_, and _truncus_; that twigs were once called _flagella_, but are now called _ramuli_; and that Mr. Link calls a straight stem, with branches on its sides, a _caulis excurrens_; and a stem, which at a certain distance above the earth breaks out into irregular ramifications, a _caulis deliquescens_. All thanks and honor be to Mr. Link! But at this moment, when we want to know _why_ one stem breaks "at a certain distance," and the other not at all, we find no great help in those splendid excurrencies and deliquescencies. "At a certain distance?" Yes: but why not before? or why then? How was it that, for many and many a year, the young shoots agreed to construct a vertical tower, or, at least, the nucleus of one, and then, one merry day, changed their minds, and built about their metropolis in all directions, nobody knows where, far into the air in free delight? How is it that yonder larch-stem grows straight and true, while all its branches, constructed by the same process as the mother trunk, and under the mother trunk's careful inspection and direction, nevertheless have lost all their manners, and go forking and flashing about, more like cracklings of spitefullest lightning than decent branches of trees that dip green leaves in dew?

§ 4. We have probably, many of us, missed the point of such questions as these, because we too readily associated the structure of trees with that of flowers. The flowering part of a plant shoots out or up, in some given direction, until, at a stated period, it opens or branches into perfect form by a law just as fixed, and just as inexplicable, as that which numbers the joints of an animal's skeleton, and puts the head on its right joint. In many forms of flowers--foxglove, aloe, hemlock, or blossom of maize--the structure of the flowering part so far assimilates itself to that of a tree, that we not unnaturally think of a tree only as a large flower, or large remnant of flower, run to seed. And we suppose the time and place of its branching to be just as organically determined as the height of the stalk of straw, or hemlock pipe, and the fashion of its branching just as fixed as the shape of petals in a pansy or cowslip.

§ 5. But that is not so; not so in anywise. So far as you can watch a tree, it is produced throughout by repetitions of the same process, which repetitions, however, are arbitrarily directed so as to produce one effect at one time, and another at another time. A young sapling has his branches as much as the tall tree. He does not shoot up in a long thin rod, and begin to branch when he is ten or fifteen feet high, as the hemlock or foxglove does when each has reached its ten or fifteen inches. The young sapling conducts himself with all the dignity of a tree from the first;--only he so manages his branches as to form a support for his future life, in a strong straight trunk, that will hold him well off the ground. Prudent little sapling!--but how does he manage this? how keep the young branches from rambling about, till the proper time, or on what plea dismiss them from his service if they will not help his provident purpose? So again, there is no difference in mode of construction between the trunk of a pine and its branch. But external circumstances so far interfere with the results of this repeated construction, that a stone pine rises for a hundred feet like a pillar, and then suddenly bursts into a cloud. It is the knowledge of the mode in which such change may take place which forms the true natural history of trees:--or, more accurately, their moral history. An animal is born with so many limbs, and a head of such a shape. That is, strictly speaking, not its history, but one fact of its history: a fact of which no other account can be given than that it was so appointed. But a tree is born without a head. It has got to make its own head. It is born like a little family from which a great nation is to spring; and at a certain time, under peculiar external circumstances, this nation, every individual of which remains the same in nature and temper, yet gives itself a new political constitution, and sends out branch colonies, which enforce forms of law and life entirely different from those of the parent state. That is the history of the state. It is also the history of a tree.

§ 6. Of these hidden histories, I know and can tell you as little as I did of the making of rocks. It will be enough for me if I can put the difficulty fairly before you, show you clearly such facts as are necessary to the understanding of great Art, and so leave you to pursue, at your pleasure, the graceful mystery of this imperfect leafage life.

I took in the outset the type of a _triple_ but as the most general that could be given of all trees, because it represents a prevalently upright main tendency, with a capacity of branching on both sides. I would have shown the power of branching on _all_ sides if I could; but we must be content at first with the simplest condition. From what we have seen since of bud structure, we may now make our type more complete by giving each bud a root proportioned to its size. And our elementary type of tree plant will be as in Fig. 46.

§ 7. Now these three buds, though differently placed, have all one mind. No bud has an oblique mind. Every one would like, if he could, to grow upright, and it is because the midmost one has entirely his own way in this matter, that he is largest. He is an elder brother;--his birthright is to grow straight towards the sky. A younger child may perhaps supplant him, if he does not care for his privilege. In the meantime all are of one family, and love each other,--so that the two lateral buds do not stoop aside because they like it, but to let their more favored brother grow in peace. All the three buds and roots have at heart the same desire;--which is, the one to grow as straight as he can towards bright heaven, the other as deep as he can into dark earth. Up to light, and down to shade;--into air and into rock:--that is their mind and purpose for ever. So far as they can, in kindness to each other, and by sufferance of external circumstances, work out that destiny, they will. But their beauty will not result from their working it out,--only from their maintained purpose and resolve to do so, if it may be. They will fail--certainly two, perhaps all three of them: fail egregiously;--ridiculously;--it may be agonizingly. Instead of growing up, they may be wholly sacrificed to happier buds above, and have to grow _down_, sideways, roundabout ways, all sorts of ways. Instead of getting down quietly into the convent of the earth, they may have to cling and crawl about hardest and hottest angles of it, full in sight of man and beast, and roughly trodden under foot by them;--stumbling-blocks to many.

Yet out of such sacrifice, gracefully made--such misfortune, gloriously sustained--all their true beauty is to arise. Yes, and from more than sacrifice--more than misfortune: from _death_. Yes, and more than death:--from the worst kind of death: not natural, coming to each in its due time; but premature, oppressed, unnatural, misguided--or so it would seem--to the poor dying sprays. Yet, without such death, no strong trunk were ever possible; no grace of glorious limb or glittering leaf; no companionship with the rest of nature or with man.

§ 8. Let us see how this must be. We return to our poor little threefold type, Fig. 46, above. Next year he will become as in Fig. 47. The two lateral buds keeping as much as may be out of their brother's way, and yet growing upwards with a will, strike diagonal lines, and in moderate comfort accomplish their year's life and terminal buds. But what is to be done next? Forming the triple terminal head on this diagonal line, we find that one of our next year's buds, _c_, will have to grow down again, which is very hard; and another, _b_, will run right against the lateral branch of the upper bud, A, which must not be allowed under any circumstances.

What are we to do?

§ 9. The best we can. Give up our straightness, and some of our length, and consent to grow short, and crooked. But _b_ shall be ordered to stoop forward and keep his head out of the great bough's way, as in Fig. 48, and grow as he best may, with the consumptive pain in his chest. To give him a little more room, the elder brother, _a_, shall stoop a little forward also, recovering himself when he has got out of _b_'s way; and bud _c_ shall be encouraged to bend himself bravely round and up, after his first start in that disagreeable downward direction. Poor _b_, withdrawn from air and light between _a_ and A, and having to live stooping besides, cannot make much of himself, and is stunted and feeble. _c_, having free play for his energies, bends up with a will, and becomes handsomer, to our minds, than if he had been straight; and _a_ is none the worse for his concession to unhappy _b_ in early life.

So far well for this year. But how for next? _b_ is already too near the spray above him, even for his own strength and comfort; much less, with his weak constitution, will he be able to throw up any strong new shoots. And if he did, they would only run into those of the bough above. (If the reader will proceed in the construction of the whole figure he will see that this is so.) Under these discouragements and deficiencies, _b_ is probably frostbitten, and drops off. The bough proceeds, mutilated, and itself somewhat discouraged. But it repeats its sincere and good-natured compliances, and at the close of the year, new wood from all the leaves having concealed the stump, and effaced the memory of poor lost _b_, and perhaps a consolatory bud lower down having thrown out a tiny spray to make the most of the vacant space near the main stem, we shall find the bough in some such shape as Fig. 49.

§ 10. Wherein we already see the germ of our irregularly bending branch, which might ultimately be much the prettier for the loss of _b_. Alas! the Fates have forbidden even this. While the low bough is making all these exertions, the boughs of A, above him, higher in air, have made the same under happier auspices. Every year their thicker leaves more and more forbid the light; and, after rain, shed their own drops unwittingly on the unfortunate lower bough, and prevent the air or sun from drying his bark or checking the chill in his medullary rays. Slowly a hopeless languor gains upon him. He buds here or there, faintly, in the spring; but the flow of strong wood from above oppresses him even about his root, where it joins the trunk. The very sap does not turn aside to him, but rushes up to the stronger, laughing leaves far above. Life is no more worth having; and abandoning all effort, the poor bough drops, and finds consummation of destiny in helping an old woman's fire.

When he is gone, the one next above is left with greater freedom, and will shoot now from points of its sprays which were before likely to perish. Hence another condition of irregularity in form. But that bough also will fall in its turn, though after longer persistence. Gradually thus the central trunk is built, and the branches by whose help it was formed cast off, leaving here and there scars, which are all effaced by years, or lost sight of among the roughnesses and furrows of the aged surface. The work is continually advancing, and thus the head of foliage on any tree is not an expansion at a given height, like a flower-bell, but the collective group of boughs, or workmen, who have got up so far, and will get up higher next year, still losing one or two of their number underneath.

§ 11. So far well. But this only accounts for the formation of a vertical trunk. How is it that at a certain height this vertical trunk ceases to be built; and irregular branches spread in all directions?

First: In a great number of trees, the vertical trunk never ceases to be built. It is confused, at the top of the tree, among other radiating branches, being at first, of course, just as slender as they, and only prevailing over them in time. It shows at the top the same degree of irregularity and undulation as a sapling; and is transformed gradually into straightness lower down (see Fig. 50). The reader has only to take an hour's ramble, to see for himself how many trees are thus constructed, if circumstances are favorable to their growth. Again, the mystery of blossoming has great influence in increasing the tendency to dispersion among the upper boughs: but this part of vegetative structure I cannot enter into; it is too subtle, and has, besides, no absolute bearing on our subject; the principal conditions which produce the varied play of branches being purely mechanical. The point at which they show a determined tendency to spread is generally to be conceived as a place of _rest_ for the tree, where it has reached the height from the ground at which ground-mist, imperfect circulation of air, &c., have ceased to operate injuriously on it, and where it has free room, and air, and light for its growth.

§ 12. I find there is quite an infinite interest in watching the different ways in which trees part their sprays at this resting-place, and the sometimes abrupt, sometimes gentle and undiscoverable, severing of the upright stem into the wandering and wilful branches; but a volume, instead of a chapter or two, and quite a little gallery of plates, would be needed to illustrate the various grace of this division, associated as it is with an exquisitely subtle effacing of undulation in the thicker stems, by the flowing down of the wood from above; the curves which are too violent in the branches being filled up, so that what was at _a_, Fig. 50, becomes as at _b_, and when the main stem is old, passes at last into straightness by almost imperceptible curves, a continually gradated emphasis of curvature being carried to the branch extremities.

§ 13. Hitherto we have confined ourselves entirely to examination of stems in one plane. We must glance--though only to ascertain how impossible it is to do more than glance--at the conditions of form which result from the throwing out of branches, not in one plane, but on all sides. "As your fingers divide when they hold a ball," I said: or, better, a large cup, without a handle. Consider how such ramification will appear in one of the bud groups, that of our old friend the oak. We saw it opened usually into five shoots. Imagine, then (Fig. 51), a five-sided cup or funnel with a stout rod running through the centre of it. In the figure it is seen from above, so as partly to show the inside, and a little obliquely, that the central rod may not hide any of the angles. Then let us suppose that, where the angles of this cup were, we have, instead, five rods, as in Fig. 52, A, like the ribs of a pentagonal umbrella turned inside out by the wind. I dot the pentagon which connects their extremities, to keep their positions clear. Then these five rods, with the central one, will represent the five shoots, and the leader, from a vigorous young oak-spray. Put the leaves on each; the five-foiled star at its extremity, and the others, now not quite formally, but still on the whole as in Fig. 3 above, and we have the result, Fig. 52, B--rather a pretty one.

§ 14. By considering the various aspects which the five rods would take in Fig. 52, as the entire group was seen from below or above, and at different angles and distances, the reader may find out for himself what changes of aspect are possible in even so regular a structure as this. But the branchings soon take more complex symmetry. We know that next year each of these five subordinate rods is to enter into life on its own account, and to repeat the branching of the first. Thus, we shall have five pentagonal cups surrounding a large central pentagonal cup. This figure, if the reader likes a pretty perspective problem, he may construct for his own pleasure:--which having done, or conceived, he is then to apply the great principles of subjection and resilience, not to three branches only, as in Fig. 49, but to the five of each cup;--by which the cups get flattened out and bent up, as you may have seen vessels of Venetian glass, so that every cup actually takes something the shape of a thick aloe or artichoke leaf; and they surround the central one, not as a bunch of grapes surrounds a grape at the end of it, but as the petals grow round the centre of a rose. So that any one of these lateral branches--though, seen from above, it would present a symmetrical figure, as if it were not flattened (A, Fig. 53)--seen sideways, or in profile, will show itself to be at least as much flattened as at B.

§ 15. You may thus regard the whole tree as composed of a series of such thick, flat, branch-leaves; only incomparably more varied and enriched in framework as they spread; and arranged more or less in spirals round the trunk. Gather a cone of a Scotch fir; begin at the bottom of it, and pull off the seeds, so as to show one of the spiral rows of them continuously, from the bottom to the top, leaving enough seeds above them to support the row. Then the gradual lengthening of the seeds from the root, their spiral arrangement, and their limitation within a curved, convex form, furnish the best _severe_ type you can have of the branch system of all stemmed trees; and each seed of the cone represents, not badly, the sort of flattened solid leaf-shape which all complete branches have. Also, if you will try to draw the spiral of the fir-cone, you will understand something about tree-perspective, which may be generally useful. Finally, if you note the way in which the seeds of the cone slip each farther and farther over each other, so as to change sides in the middle of the cone, and obtain a reversed action of spiral lines in the upper half, you may imagine what a piece of work it would be for both of us, if we were to try to follow the complexities of branch order in trees of irregular growth, such as the rhododendron. I tried to do it, at least, for the pine, in section, but saw I was getting into a perfect maelström of spirals, from which no efforts would have freed me, in any imaginable time, and the only safe way was to keep wholly out of the stream.

§ 16. The alternate system, leading especially to the formation of forked trees, is more manageable; and if the reader is master of perspective, he may proceed some distance in the examination of that for himself. But I do not care to frighten the general reader by many diagrams: the book is always sure to open at them when he takes it up. I will venture on one which has perhaps something a little amusing about it, and is really of importance.

56. Sketch by a Clerk of the Works.]

§ 17. Let X, Fig. 54, represent a shoot of any opposite-leaved tree. The mode in which it will grow into a tree depends, mainly, on its disposition to lose the leader or a lateral shoot. If it keeps the leader, but drops the lateral, it takes the form A, and next year by a repetition of the process, B. But if it keeps the laterals, and drops the leader, it becomes first, C and next year, D. The form A is almost universal in spiral or alternate trees; and it is especially to be noted as bringing about this result, that in any given forking, one bough always goes on in its own direct course, and the other leaves it softly; they do not separate as if one was repelled from the other. Thus in Fig. 55, a perfect and nearly symmetrical piece of ramification, by Turner (lowest bough but one in the tree on the left in the "Château of La belle Gabrielle"), the leading bough, going on in its own curve, throws off, first, a bough to the right, then one to the left, then two small ones to the right, and proceeds itself, hidden by leaves, to form the farthest upper point of the branch.

The lower secondary bough--the first thrown off--proceeds in its own curve, branching first to the left, then to the right.

The upper bough proceeds in the same way, throwing off first to left, then to right. And this is the commonest and most graceful structure. But if the tree loses the leader, as at C, Fig. 54 (and many opposite trees have a trick of doing so), a very curious result is arrived at, which I will give in a geometrical form.

§ 18. The number of branches which die, so as to leave the main stem bare, is always greatest low down, or near the interior of the tree. It follows that the lengths of stem which do not fork diminish gradually to the extremities, in a fixed proportion. This is a general law. Assume, for example's sake, the stem to separate always into two branches, at an equal angle, and that each branch is three quarters of the length of the preceding one. Diminish their thickness in proportion, and carry out the figure any extent you like. In Plate 56, opposite, Fig. 1, you have it at its ninth branch; in which I wish you to notice, first, the delicate curve formed by every complete line of the branches (compare Vol. IV. Fig. 91); and, secondly, the very curious result of the top of the tree being a broad flat line, which passes at an angle into lateral shorter lines, and so down to the extremities. It is this property which renders the contours of tops of trees so intensely difficult to draw rightly, without making their curves too smooth and insipid.

Observe, also, that the great weight of the foliage being thrown on the outside of each main fork, the tendency of forked trees is very often to droop and diminish the bough on one side, and erect the other into a principal mass.[1]

§ 19. But the form in a perfect tree is dependent on the revolution of this sectional profile, so as to produce a mushroom-shaped or cauliflower-shaped mass, of which I leave the reader to enjoy the perspective drawing by himself, adding, after he has completed it, the effect of the law of resilience to the extremities. Only, he must note this: that in real trees, as the branches rise from the ground, the open spaces underneath are partly filled by subsequent branchings, so that a real tree has not so much the shape of a mushroom, as of an apple, or, if elongated, a pear.

§ 20. And now you may just begin to understand a little of Turner's meaning in those odd pear-shaped trees of his, in the "Mercury and Argus," and other such compositions: which, however, before we can do completely, we must gather our evidence together, and see what general results will come of it respecting the hearts and fancies of trees, no less than their forms.

FOOTNOTE:

[1] This is Harding's favorite form of tree. You will find it much
insisted on in his works on foliage. I intended to have given a
figure to show the results of the pressure of the weight of all the
leafage on a great lateral bough, in modifying its curves, the
strength of timber being greatest where the leverage of the mass
tells most. But I find nobody ever reads things which it takes any
trouble to understand, so that it is of no use to write them.