V The Brush Pile
Today I visited the brush pile back of the orchard. Here the trimmings of the winter are placed, waiting to be burned when dry. How many are the archives that will be destroyed! Here are histories in every bud and twig and scar, of the seasons, of the accidents and deaths, the records of the tree as there are records of families.
These records are not written in numbers or in letters, nor yet in hieroglyphs; yet are they understandable. Alphabet is not needed, and the key is simple.
From the brush pile of records I took one. I must describe it in part by a picture (Fig. 14). On the living trees at this writing the petals mostly have fallen and the leaves are nearly full grown. This branch was cut in winter. It has lain in the snow and rain, putting forth no flowers or leaves. Yet we can read it.
It is May, 1921. The terminal shoot is obviously of 1920; we shall name it No. 1. It is a foot long, smooth and glossy, terminating at the base (o) in a “ring” and at a short stub or branchlet. If we count the buds on all sides of the shoot and at the tip we find them to be 13. The largest one is at the tip, and they are mostly successively smaller toward the base. Apparently the growth-energy was expended in the upper parts of the twig, making large full buds. In fact, the three or four lowermost buds are scarcely developed and would not grow unless the limb were broken off above them; they are dormant buds.
Looking along the shoot, I find that every six buds stand in the same line: the sixth bud is over the first, seventh over the second, eighth over the third. If I were to fasten a string to bud No. 1 and wind it around the stem to my left, passing over every bud until I had reached the sixth, I should find that it had made two circuits of the stem (passed twice around it) and had passed over five spaces between buds. This is the leaf-arrangement or phyllotaxy of the apple-tree, expressed by the fraction 2/5. The space between two buds is two-fifths of a diameter, and two circuits (ten-fifths) must be passed before a bud comes over the one from which we started. The 2/5 leaf-arrangement obtains on cherry, peach, apricot, pear, raspberry and many others; but a very different order is that of the linden, grape, currant, lilies, elm, maple.
We cannot understand this simple unbranched terminal twig (No. 1) until we know what took place last year. A year ago, in the spring of 1920, a terminal bud that had formed in 1919 expanded and gave rise to this rapidly growing shoot. By the end of May or early June this shoot had grown to twelve inches long, for the growth in length on the twigs of trees is usually completed that early. This shoot bore leaves on the 2/5 arrangement; in the axil of every leaf was a bud, the strongest buds being with the strongest leaves at the middle and top of the shoot; in the autumn of 1920 these leaves fell, but the buds remained, persisted the winter, and were ready to “grow” in the early spring of 1921. We see them on No. 1 (Fig. 14).
In 1921 these buds on No. 1, then, would have grown. New leaves would have come from the bud itself; in fact, the winter buds of the apple are packed with miniature leaves and sometimes with flowers as well. The shoot coming out of the bud may remain very short, constituting a “spur,” or grow with long internodes, making a slender twig. Fig. 15 shows a branch with new elongated growth, b to a, and a shoot or spur (c) arising from a bud of the previous year. Note the “ring,” or division beyond b, marking the turn of the year.
It will be noted in Fig. 14 that the buds are of two shapes and sizes, such as a, a, a, representing one kind and b, b, the other kind. The former, small and pointed, are leaf-buds; from them will arise a shoot bearing only leaves. The latter, b, large and rounded and usually more fuzzy, are flower-buds (fruit-buds): from them will arise a short shoot bearing leaves and a cluster of flowers; and we hope that at least one of the flowers will set fruit.
We are now ready to resume our lesson with the branch before us. We have identified the slender terminal part, No. 1, as the growth of 1920. We are now to account for all the remaining buds and branchlets.
If No. 1 grew in 1920, then the main shoot of No. 2 grew in 1919, from the point o o. It is also one foot long. Near its base are four small buds that remained dormant in 1920. There are nine branches (d) of various lengths besides the terminal shoot No. 1, all of which grew in 1920, for they are naturally a year younger than the main axis from which they arise; these branches are the same age as No. 1, with buds that would have produced shoots in 1921. But the terminal buds of eight of these lateral shoots (all but the lowermost) bear blossom-buds at the end; note their size and shape. Had not the branch been cut, these buds would have bloomed in 1921; the eight of them would have produced probably forty to fifty flowers; perhaps two or three good fruits would have resulted. Note that two of the lateral branches or spurs are short and weak: these would soon perish. The No. 2 branch has a dead end (e); in some way the terminal bud was destroyed, and No. 1 sprang from a lateral bud beneath it, changing the direction of growth.
If No. 2 grew in 1919, then No. 3 grew in 1918. It also grew about one foot in length, showing that the conditions in the three years must have been very uniform. There are remains of five dormant buds at its base. There are seven side branches. As the main axis is three years old, so these lateral shoots are two years old; they are the same age as the axis No. 2. The lower one (s) grew less than an inch in 1919, and made a fruit-bud; in 1920 it blossomed and one fruit set as is shown by the square scar at the end; as the scar is small and the twig weak, we are safe in assuming that the apple was very small or else did not mature. A bud formed at the side of s to continue the growth of the spur next year (1921), but it is a leaf-bud; apparently there was not sufficient energy to bear flowers and to make a fruit-bud; so there would have been no more fruit on this spur earlier than 1922: thus do we see that the alternate bearing of the apple-tree may have some of its origin in the fruit-spur.
The side spur f produced a terminal blossom-bud in 1919. In 1920 six flowers opened,—I could count the scars. One of the flowers produced a fruit, as I tell by the square scar at the end; the thickened stem also indicates fruit-bearing. The side bud in this case is a fruit-bud, but it is small and weak and is probably incapable of producing a fruit. There are no strong leaf-buds to take up the work, and this spur (f) would probably soon have died, as also would spur s.
The side shoot g grew to h in 1919 and made a flower-bud. In 1920 this bud gave blossoms and one fruit resulted; the scar is prominent and there is an enlargement of the tissue indicating that the fruit probably attained good size; in 1920 also, two side spurs were formed each with weak blossom-buds, also a terminal shoot (beyond h) with leaf-bud at the end.
The other shoots have similar histories: the long shoot i bore a fruit-bud at k in 1919 and a fruit in 1920; in 1920 it also made three lateral shoots and a terminal shoot, with flower-buds terminating two of them. Shoot l bore flowers at its point in 1920 but did not carry the fruit to maturity; it also made two side growths and one terminal growth, all terminated by flower-buds, to be blown in 1921. The shoot m is a short spur that made a flower-bud in 1919 and in 1920 carried three little fruits for a time and made a flower-bud in 1920. Shoot n remained very short in 1919, making a terminal leaf-bud; in 1920 it grew two inches and made a weak flower-bud.
If shoot No. 3 grew in 1918, then No. 4 grew in 1917; but the branch is severed and I cannot trace the record farther. We could trace the family history many years if we had the unpruned tree before us.
Here, then, in my yard-long manuscript are forty bud-records on the main axis, counting the terminals on No. 2 and No. 3. I can find record of 144 buds on the side shoots. This makes a grand total of 184 buds. There is a total growth in length of 108 inches, or 9 feet. Each of the buds that has already “grown” has produced an average of probably ten leaves, or say 340 leaves in total. If there were an average of five flowers to the cluster, then about 150 flowers would have been carried on my branch, with the potentiality of 150 fruits; but in fact not more than three or four maturing fruits would have been produced in these years: and I should think this a good proportion as blossoms and apples go. Certainly the branch has done its part. There have been three eventful years.
I would not have my reader to suppose that one may always distinguish leaf-buds and fruit-buds at a glance. I may be mistaken in some of the above determinations, but they are essentially correct for I have the twig before me. In some varieties of apples the differences between the two kinds of buds are less marked. The certain way is to dissect the bud: one may then see what it contains.
It now remains to determine how the branch was placed in the tree. It must have been upright or very nearly so, for the main axis is essentially straight and the branchlets are about equally developed on all sides; moreover, there is no indication in the bark that one exposure was the “weather side.” The big twig i apparently found a light and unoccupied space into which to develop, but its extension is not greatly out of proportion. I suppose, however, that my branch was not topmost in the tree; there is no indication in very long growth or strong upward tendency of the branchlets to mark the branch as a “leader.”
Years ago I became fascinated with the study of knots and knot-holes in the timber of wood-piles. They are excellent records of the events in the life of trees. In print I have tried to show what they mean. I also worked out the life-histories of twigs and published them in nature-study leaflets and elsewhere. Hundreds of children were interested in the twigs and buds, finding them unusual, every one of them a different story, and yet not difficult to read. These lessons gave meaning to trees and seasons. Such observations have always meant much to me, even when made in the most casual way in the midst of constraining activities. And now in this later day I come back to a bare twig with all the joy of youth. The records of the years are in these piles of brush.