Gateway to the Classics: Handbook of Nature Study: Trees by Anna Botsford Comstock
 
Handbook of Nature Study: Trees by  Anna Botsford Comstock

The Pine

Teacher's Story

dropcap image ONE other of our native trees is more beautiful than the pine. In the East, we have the white pine with its fine-tasselled foliage, growing often 150 to 200 feet in height and reaching an age of from two to three hundred years. On the Pacific coast, the splendid sugar pine lifts its straight trunk from two to three hundred feet in height; and although the trunk may be from six to ten feet in diameter yet it looks slender, so tall is the tree. A sugar pine cone on my desk measures 22 inches in length and weighs almost one pound, although it is dried and emptied of seed.

There is something majestic about the pines, which even the most ignorant feel. Their dark foliage outlined against wintry skies appeals to the imagination, and well it may, for it represents an ancient tree-costume. The pines are among the most ancient of trees, and were the contemporaries of those plants which were put to sleep, during the Devonian age, in the coal beds. It is because the pines and the other evergreens belong essentially to earlier ages, when the climate was far different than it is to-day, that they do not shed their leaves like the more recent, deciduous trees. They stand among us, representatives of an ancient race, and wrap their green foliage about them as an Indian sachem does his blanket, in calm disregard of modern fashion of attire.

All cone-bearing trees have typically a central stem from which the branches come off in whorls, but so many things have happened to the old pine trees that the evidence of the whorls is not very plain; the young trees show this method of growth clearly, the white pine having five branches in each whorl. Sometimes pines are seen which have two or three stems near the top; but this is a story of injury to the tree and its later victory.

The very tip of the central stem in the evergreens is called "the leader," because it leads the growth of the tree upward; it stretches up from the center of the whorl of last year's young branches, and there at its tip are the buds which produce this year's branches. There is a little beetle which seems possessed of evil, for it likes best of all to lay its rascally eggs in the very tip of this leader; the grub, after hatching, feeds upon the bud and bores down into the shoot, killing it. Then comes the question of which branch of the upper whorl shall be elected to rise up and take the place of the dead leader; but this is an election which we know less about than we do of those resulting from our blanket ballots. Whether the tree chooses, or whether the branches aspire, we may not know; but we do know that one branch of this upper whorl arises and continues the growth of the tree. Sometimes there are two candidates for this position, and they each make such a good struggle for the place that the tree grows on with two stems instead of one—and sometimes with even three. This evil insect injures the leaders of other conifers also, but these are less likely to allow two competitors to take the place of the dead leader.


[Illustration]

The young and the mature cones of white pine.

Photo by Ralph Curtis.

The lower branches of many of the pines come off almost at right angles from the bole; the foliage is borne above the branches, which gives the pines a very different appearance from that of other trees. The foliage of most of the pines is dark green, looking almost black in winter; the pitch pine has the foliage yellowish green, and the white pine, bluish green; each species has its own peculiar shade. There is great variation in the color and form of the bark of different species. The white pine has nearly smooth bark on the young trees, but on the older ones it has ridges that are rather broad, flat and scaly, separated by shallow sutures, while the pitch pine has its bark in scales like the covering of a giant alligator.


[Illustration]

A part of a necklace of pitch pine needles.

The foliage of the pine consists of pine needles set in little bundles on raised points which look like little brackets along the twigs. When the pine needles are young, the bundle is enclosed in a sheath making the twig look as if it were covered with pin-feathers. In many of the species this sheath remains, encasing the base of the bundle of needles; but in the white pine it is shed early. The number of leaves in the bundle helps to determine the tree; the white pine has five needles in each bunch, the pitch pine has three, while the Austrian pine has two. There is a great difference in the length and the color of the needles of different species of pine. Those of the white pine are soft, delicate and pliable, and from three to four inches in length; the needles of the pitch pine are stiff and coarse and about the same length; the white pine needles are triangular in section, and are set so as to form distinct tassels, while those of the Austrian pine simply clothe the ends of the twigs. The needles of the pine act like the strings of an aeolian harp; and the wind, in passing through the tree, sets them into vibration, making a sighing sound which seems to the listener like the voice of the tree. Therefore, the pine is the most companionable of all our trees and, to one who observes them closely, each tree has its own tones and whispers a different story.


[Illustration]

Austrian pine in blossom showing staminate flowers.

Photo by G. F. Morgan.

The appearance of the unripe cone is another convincing evidence that mathematics is the basis of the beautiful. The pattern of the overlapping scales is intricate and yet regular—to appreciate it one needs to try to sketch it. Beneath each scale, when it opens wide, we find nestled at its base two little seeds in twin boxes; each provided with a little wing so that it can sail off with the wind to find a place to grow. The shape of the scales of the cone is another distinguishing character of the pine, and sketching the outside of scales from several different species of pine cones will develop the pupils' powers of observation; the tip of the scale may be thickened or armed with a spine, and one wonders if these spines are for the purpose of discouraging the squirrels from stealing the green seeds.


[Illustration]

White pine, staminate blossoms and empty cones.

Photo by Morgan.

The pine cone requires two years for maturing; the pistillate flower from which it is developed is a tiny cone with each scale spread wide and standing upright to catch the pollen for the tiny ovule nestled within it. The pistillate flower of the white pine grows near the tip of the new twig, and is pinkish in color. In the Austrian pine it is the merest pink dot at first, but after a little shows itself to be a true cone with pink-purple scales, which stand up very erect, and makes a pretty object when viewed through a lens; each scale is pink at its three-pointed tip, with pink wings just below, the inner portions being pale green. The cone is set just beside the growing tip of the twig, is pointed upward, and its sheath-scales are turned back like chaff around its base.

In June when the new shoots of the pine twigs stand up like pale green candles on a Christmas tree, at their bases may be found the staminate catkins set in radiating whorls, making galaxies of golden stars against the dark green background of foliage. In the Austrian pine, one of these pollen catkins may be an inch or two long and a half-inch in width; each little scale of this cone is an anther sac, filled to bursting with yellow pollen. From these starry pollen cones there descends a yellow shower every time a breeze passes; for the pine trees depend upon the wind to sift their pollen dust into the lifted cups of the cone scales, which will close upon the treasure soon. The pollen grains of pine are very beautiful when seen through a microscope; and it seems almost incredible that the masses of yellow dust sifted in showers from the pines when in blossom, should be composed of these beautiful structures. When the pine forests on the shores of the Great Lakes are in bloom, the pollen covers the waves for miles out from the shores.


[Illustration]

White pine.

If we examine the growing tips of the pine branches, we find the leaves look callow and pin-feathery. The entire leaf is wrapped in a smooth, shining, silken sheath, at the tip of which its green point protrudes. The sheath is tough like parchment and is cylindrical because the pine needles within it are perfectly adjusted one to another in cylindrical form. The sheath is made up of several layers, one over the other, and may be pulled apart. The new leaves are borne on the new, pale green wood.


[Illustration]

Yellow pine on the brink of the Little Yosemite Valley.

Photo by G. K. Gilbert.
Courtesy of U.S. Geographical Survey.

The uses of pines are many. The lumber of many of the species, especially that of the white pine, is free from knots and is used for almost everything from house-building to masts for ships. In the Southern States, the long-leafed pines are tapped for resin, which is not the sap of the tree, as is generally supposed. Pine sap is like other sap; the resin is a product of certain glands of the tree, and is of great use to it in closing wounds and thus keeping out the spores of destructive fungi. It is this effort of the tree to heal its wounds that makes it pour resin into the cuts made by the turpentine gatherers. This resin is taken to a distillery, where the turpentine is given off as a vapor and condensed in a coiled tube which is kept cold. What is left is known as "rosin."


Lesson CCII

The Pine

Leading thought—The pines are among our most ancient trees. Their foliage is evergreen but is shed gradually. The pollen-bearing and the seed-bearing flowers are separate on the tree. The seeds are winged and are developed in cones.


Method—At least one pine tree should be studied in the field. Any species will do but the white pine is the most interesting. The Austrian pine which is commonly planted in parks is a good subject. The leaves and cones may be studied in the schoolroom, each pupil having a specimen.


Observations—

1. What is the general shape of the pine tree? Is there one central stem running straight up through the center of the tree to the top? Do you find any trees where this stem is divided into two or three near the top? Describe how the pine tree grows. What is the "leader?" What happens if the leader is injured? How do the topmost branches of the young pine look? Do they all come off from the same part of the stem? How many are there in a whorl?

2. What color is the bark? Is it ridged or in scales?

3. Do the branches come off the main stem at right angles or do they lift up or droop down? Where is the foliage borne on the branches? What is the color of the foliage? Is the pine foliage ever shed or does the pine leaf, when it comes, stay on as long as the tree lives?

4. Study the pine leaves. Why are they called needles? Note that they grow several together in what we call a bundle. How many in one bundle? Is the bundle enclosed in a little sheath at the base? Are the bundles grouped to make distinct tassels? Study one of the needles. How long is it? Is it straight or curved? Flexible or coarse and stiff? Cut it across and examine it with a lens. What is the outline in cross section? Why does the wind make a moaning sound in the pines?


[Illustration]

White pine cone.

5. Study a pine cone. Does it grow near the tip of the branch or along the sides? Does it hang down or stand out stiffly? What is its length? Sketch or describe its general shape. Note that it is made up of short, over-lapping scales. What pattern do the scales make as they are set together? Describe or sketch one scale; has it a thickened tip? Is there a spine at the tip of the scale?

6. Where in the cone are the seeds? Describe or sketch a pine seed. How long is its wing? How is it carried and planted? When the cone opens, how are the seeds scattered? What creatures feed upon the pine seed?

7. Study the pine when in blossom, which is likely to occur in June. This time is easily determined because the air around the tree is then filled with the yellow pollen dust. Study the pollen-bearing flower. Is it conelike in form? Does it produce a great deal of pollen? If you have a microscope, look at the pollen through a high objective and describe it. How many of the pollen catkins are clustered together? On what part of the twigs are they borne? Where are the pistillate flowers which are to form the young cones? How large are they and how do they look at the time the pollen is flying? Do they point upward or droop downward? Why? Look beneath the scales of a little cone with a lens and see if you can find the flowers. What carries the pine pollen to the flowers in the cone?

8. Name all the uses for pine lumber that you know. Write an English theme on how turpentine is produced from pines and the effect of this industry upon pine forests. Where does resin appear on the pine? Of what use is it to the tree? Do you think it is pine sap? What is the difference between resin and rosin?

9. How long do the pine trees live? Write a story of all that has happened to your neighborhood since the pine tree which you have been studying was planted.

10. Make the following drawings: A bundle of pine needles showing the sheath and its attachment to the twig; the cone; the cone scale; the seed. Sketch a pine tree.


Supplementary reading—Trees in Prose and Poetry, pp. 32, 151, 152; The Spirit of the Pine, Bayard Taylor; To a Pine Tree, Lowell; Nature in Verse, pp. 15, 288.


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