Cornell Nature-Study Leaflets / Being a selection, with revision, from the teachers' leaflets, home nature-study lessons, junior naturalist monthlies and other publications from the College of Agriculture, Cornell University, Ithaca, N.Y., 1896-1904

by New York State College of Agriculture

A hemlock twig is an interesting object. It may have many characters in common with the spruce and fir; yet the impression which we get from it, or from a large hemlock tree, is entirely distinct. The arrangement of the leaves and the gracefulness of the drooping branchlets are most pleasing. We are led to examine it more closely. We notice that the leaves appear to be borne in two more or less regular rows,—one on each side of the branch or twig; but in reality they come from all sides of the branch, and it is the position which the leaves assume that gives this two-rowed appearance.

The leaves have a short stalk or petiole, and this stalk rests along the side of the branchlet in such a direction that the leaves are placed in single rows on either side of the branch. The petioles of the leaves are nearly parallel with the branch while the leaves often make a decided angle with the petiole. This fact can best be brought out by carefully examining a small twig.

While we are noting the arrangement of the leaves on the branchlets, we should also notice the points of similarity and difference between these leaves and those of the spruces and firs. We shall find that there is more in common, at least so far as shape and color are concerned, between the hemlock and the fir than between the hemlock and the spruce.

Fig. 243. Spray of the hemlock. Two-thirds natural size.

The small, delicate cones, borne on the tips of the branchlets, will also attract our attention ([Fig. 243].) We may wonder at their small size, for they are only about three-quarters of an inch long, and very delicate; yet a second glance at the tree will impress us with the number of cones which the tree bears, and we conclude that, although the cones may be small, yet there are so many of them that there will be no lack of seeds.

It is more difficult to trace the age of a hemlock limb than of many other kinds of trees, yet we can easily determine that many of the leaves are several years old when they fall.

The bark of the hemlock is used in tanning hides for leather. The tree is much used for lumber. Where does it grow?

The Arbor-vitæ.

One might almost wonder, at first sight, if the arbor-vitæ (often, but wrongly, called the white cedar) has any leaves at all. It does possess them, however, but they are very different in size and shape from any of the others that we have examined. They are small scale-like bodies, closely pressed together along the sides of the branchlets, in four rows. Leaves pressed to the branches in this manner are said to be "appressed." The leaves of the arbor-vitæ are so close together that they overlap one another. The leaves are of two distinct shapes, sometimes known as the surface leaves and the flank leaves. The former are located on what appears to be the flattened surface of the branchlets, while the latter are on the sides or edges. See [Fig. 244].