Trees of the Northern United States Part 3

Dry fruits with spreading, wing-like appendages, as in the Ash (Fig.

11), Maple (Fig. 12), Elm (Fig. 13), and Ailanthus, are called _samaras_ or _keys_.

Dry fruits, usually elongated, containing generally several seeds, are called _pods_. If there is but one cell and the seeds are fastened along one side, _Pea-like pods_, or _legumes_. Locust. The term _capsule_ indicates that there is more than one cell. Catalpa, Hibiscus.

[Ill.u.s.tration: Fig. 13.]

All the dry, scaly fruits, usually formed by the ripening of some sort of catkin of flowers, will be included under the term _cone_. Pine, Alder, [Ill.u.s.tration] Magnolia. If the appearance of the fruit is not much different from that of the cl.u.s.ter of flowers, as in the Hornbeams, Willows, and Birches, the term _catkin_ will be retained for the fruit also. The scales of a cone may lap over each other; they are then said to be _imbricated_ or _overlapping_, [Ill.u.s.tration] (Pine); or they may merely touch at their edges, when they are _valvate_ [Ill.u.s.tration]

(Cypress). When cones or catkins hang downward, they are _pendent_. If the scales have projecting points, these points are _spines_ if strong, and _p.r.i.c.kles_ if weak. The parts back of the scales are _bracts_; these often project beyond the scales, when they are said to be _exserted_.

[Ill.u.s.tration] Sometimes the exserted bracts are bent backward; they are then said to be _recurved_ or _reflexed_.

CHAPTER V.

_Winter Study of Trees._

Many of the peculiarities of trees can be studied much better during the winter and early spring than at any other time of the year. The plan of branching, the position, number, size, form, color, and surface of buds, as well as the arrangement of the leaves within the bud and the peculiarities of the scales that cover them, are points for winter investigation.

GENERAL PLAN OF BRANCHING.--There are two distinct and readily recognized systems of branching. 1. The main stem is _excurrent_ (Fig.

3) when the trunk extends as an undivided stem throughout the tree to the tip; this causes the spire-like or conical trees so common among narrow-leaved evergreens. 2. The main stem is _deliquescent_ (Fig. 4) when the trunk divides into many, more or less equal divisions, forming the broad-topped, spreading trees. This plan is the usual one among deciduous trees. A few species, however, such as the Sweet Gum and the Sugar-maple, show the excurrent stem while young, yet even these have a deliquescent stem later in life. The English Maple and the Apple both have a deliquescent stem very early.

All the narrow-leaved evergreens, and many of the broad-leaved trees as well, show what is called _definite_ annual growths; that is, a certain amount of leaf and stem, packed up in the winter bud, spreads out and hardens with woody tissue early in the year, and then, no matter how long the season remains warm, no additional leaves or stem will grow.

The buds for the next year's growth then form and often become quite large before autumn.

There are many examples among the smaller plants, but rarely one among the trees, of _indefinite_ annual growth; that is, the plant puts forth leaves and forms stems throughout the whole growing-season. The common Locust, the Honey-locust, and the Sumacs are ill.u.s.trations.

BUDS.--Buds are either undeveloped branches or undeveloped flowers. They contain within the scales, which usually cover them, closely packed leaves; these leaves are folded and wrinkled in a number of different ways that will be defined at the end of this chapter.

[Ill.u.s.tration: Fig. 14.]

POSITION AND NUMBER.--While the axils of the leaves and the ends of the stems are the ordinary places for the buds, there are many peculiarities in regard to their exact position, number, etc., that render them very interesting for winter study. Sometimes there are several to the single leaf. In the Silver Maple there are buds on each side of the true axillary one; these are flower-buds, and during the winter they are larger than the one which produces the branch. The b.u.t.ternut (Fig. 14) and the Walnut have several above each other, the upper one being the largest and at quite a distance from the true axil. In these cases the uppermost is apt to grow, and then the branch is said to be _extra-axillary_. In the Sycamore the bud does not show while the leaf remains on the tree, as it is in the hollow of the leafstalk. In the winter the bud has a ring-like scar entirely around it, instead of the moon-shaped scar below as in most trees. The Common Locust has several buds under the leafstalk and one above it in the axil. This axillary bud may grow during the time the leaf remains on the tree, and afterward the growth of the strongest one of the others may give the tree two branches almost together.

Some plants form extra buds especially when they are bruised or injured; those which have the greatest tendency to do so are the Willows, Poplars, and Elms. Such buds and growths are called _advent.i.tious_. By cutting off the tops or _pollarding_ such trees, a very great number of advent.i.tious branches can be made to grow. In this way the Willow-twigs used for baskets are formed. Advent.i.tious buds form the cl.u.s.ters of curious thorns on the Honey-locust and the tufts of whip-like branches on the trunks and large limbs of the Elms.

In trees the terminal bud and certain axillary ones, differing according to the species or variety of tree, are, during the winter, much larger than the rest. These are the ones which naturally form the new growth, and upon their arrangement the character of branching and thus the form of the tree depend. Each species has some peculiarity in this regard, and thus there are differences in the branching of all trees. In opposite-leaved plants the terminal bud may be small and weak, while the two buds at its side may be strong and apt to grow. This causes a forking of the branches each year. This plan is not rare among shrubs, the Lilac being a good example.

BUD-SCALES.--The coverings of buds are exceedingly varied, and are well worthy of study and investigation. The large terminal buds of the Horse-chestnut, with their numerous scales, gummy on the outside to keep out the dampness, and hairy within to protect them from sudden changes of temperature, represent one extreme of a long line; while the small, naked, and partly buried buds of the Honey-locust or the Sumac represent the other end.

The scales of many buds are merely extra parts formed for their protection, and fall immediately after the bursting of the buds; while other buds have the stipules of the leaves as bud-scales; these remain on the twigs for a time in the Tulip-tree, and drop immediately in the Magnolia.

FORMS OF BUDS.--The size of buds varies greatly, as before stated, but this difference in size is no more marked than the difference in form.

There is no better way to recognize a Beech at any time of the year than by its very long, slender, and sharp-pointed buds. The obovate and almost stalked buds of the Alders are also very conspicuous and peculiar. In the Balsam Poplar the buds are large, sharp-pointed, and gummy; in the Ailanthus they cannot be seen.

[Ill.u.s.tration: Fig. 15.]

All the things that might be learned from a small winter twig cannot be shown in an engraving, but the figures here given ill.u.s.trate some of the facts easily determined from such specimens. The first twig (Ash) had opposite leaves and is 3 years old (the end of each year's growth is marked by dotted lines on all the figures); the year before last it had 6 leaves on the middle portion; last year it had 8 leaves on the end portion and 12 on the side shoots of the middle portion. The buds near the end of the annual growth are strongest and are most apt to grow.

The specimen ill.u.s.trated was probably taken from the end of a branch of a rather young and luxuriantly growing tree. Thus the Ash must have quite a regular growth and form a regularly outlined tree.

The second twig (Sweet Gum) shows 7 years' growth and is probably a side shoot from more or less within the tree-top. It is stunted in its growth by the want of light and room. The leaves were alternate.

The third twig (Sycamore) also had alternate leaves; the pointed buds must have been under the leafstalks, as the leaf-scars show as rings around the buds. The larger branch grew three years ago. From the specimen one judges that the Sycamore is quite an irregularly formed tree. The twig had 11 leaves last year.

The fourth twig (Silver Maple) shows that the plant had opposite leaves, and supernumerary buds at the sides of the true axillary ones; the true axillary buds are smaller than those at the sides. It would, in such cases, be reasonable to suppose that the supernumerary buds were floral ones, and that the plant blooms before the leaves expand. The annual growths are quite extended; two years and a part of the third make up the entire twig. If it was cut during the winter of 1891-92, it must have had leaves on the lower part in 1889 and 12 leaves on the middle portion in 1890, as well as probably 4 on the lower portion on the side shoots. Last year it had 14 leaves on the end portion, two at least on each side shoot below, making 24 in all.

_Folding of Leaves in the Bud._

There are some peculiarities in the arrangement of leaves in the bud which can be investigated only in the early spring. The common plans among trees are--_Inflexed_: blade folded crosswise, thus bringing it upon the footstalk. Tulip-tree. _Conduplicate_: blade folded along the midrib, bringing the two halves together. Peach. _Plicate_: folded several times lengthwise, like a fan. Birch. _Convolute_: rolled edgewise from one edge to the other. Plum. _Involute_: both edges rolled in toward the midrib on the upper side. Apple. _Revolute_: both edges rolled backward. Willow. _Obvolute_: folded together, but the opposite leaves half inclosing each other. Dogwood.

CHAPTER VI.

_The Preparation of a Collection._

[Ill.u.s.tration: Fig. 16.]

Three specimens are needed of each kind of tree: one, a branch showing the flowers; another, showing the fruit--one of these, and in many cases both, will show the leaves. The third specimen, cut from a large limb or trunk, shows the bark and the wood. This should be a specimen with a surface so cut as to show the wood in the direction of the silver grain, _radial section_; with another surface cut in the direction of the annual layers, _tangential section_; and with a third cut across the grain, _cross-section_. It should be a specimen old enough to show the change of color in the heart-wood. By taking a limb or trunk 8 inches in diameter, all these points can be secured. A specimen cut as shown in the figure will ill.u.s.trate all the desired points. Side E F G shows sap-and heart-wood in tangential section; side A B D C shows the same in radial section; end A B F E, in cross-section; and B F G D shows the bark. The central pith is at I; the heart-wood extends from C to J; the sap-wood from J to D. The silver grain is well shown at the end, and the blotches formed by it on the radial section.

By having the piece made smooth, and the upper part down to the center (H) varnished, the appearance of the wood in furniture or inside finish will be ill.u.s.trated.

The specimens should be as nearly uniform in size as possible. If a limb 8 inches in diameter be taken and a length of 6 inches be cut off, the section A B D C should pa.s.s through the line of pith; the section E F G should be parallel with this at a distance from it of two inches; and two inches from the line of pith, the section A E C should be made. The whole specimen will then be 6 inches wide and long, and 2 inches thick.

The twigs containing leaves, flowers and fruit need to be pressed while drying in order that they may be kept in good form and made tough enough to be retained as specimens. The plants should be placed between a large supply of newspapers, or, better still, untarred building-felt, while drying. A weight of from 40 to 80 pounds is needed to produce the requisite pressure. The weight is placed upon a board covering the pile of plants and paper. On account of the size of many leaves and flower-cl.u.s.ters, these pressed specimens of trees should not be shorter than from 12 to 15 inches, and even a length of 18 inches is an advantage. The pads or newspapers should be about 12 by 18 inches. A transfer of the plants into dry pads each day for a few days will hasten the drying and increase the beauty of the specimens. The specimens of twigs can be mounted on cardboard by being partly pasted and partly secured by narrow strips of gummed cloth placed across the heavier portions. The cardboard should be uniform in size. One of the regular sizes of Bristol-board is 22 by 28 inches; this will cut into four pieces 11 by 14. Specimens not over 15 inches in length can readily be mounted on these, and for most collectors this might be a very convenient size. Another regular size is 22 by 32 inches, cutting well into pieces 11 by 16. Specimens 15 to 18 inches long can be mounted on these.

Some kinds of Evergreens, the Spruces especially, tend to shed their leaves after pressing. Such kinds can in most cases be made to form good specimens without pressing. Fasten the fresh specimens on pillars of plaster in boxes or frames 2 to 3 inches deep, so that they touch nothing but the column of plaster. Mix calcined plaster in water (as plasterers do), and build up a column high enough to support the branch.

Place the specimen on the top of the pillar already formed, and pour over the whole some quite thin plaster till a rounded top is formed completely fastening the specimen. If the leaves are not touched at all, after they are dry, they will hang on for a long time, making specimens that will show the tree characteristics better than pressed specimens possibly could.

CHAPTER VII.

_Figures to be used in Botanical Description._

[Ill.u.s.tration: Fig. 17.]

[Ill.u.s.tration: Fig. 18.]