The "canoe-birch" is not the only species of these trees found in North America. The genus _Betula_ (so called from the Celtic word _batu_, which means birch) has at least half-a-dozen other known representatives in these parts. There is the "white birch," a worthless tree of some twenty feet in height, and less than six inches diameter. The bark of this species is useless, and its wood, which is soft and white, is unfit even for fuel. It grows, however, in the poorest soil. Next there is a species called the "cherry-birch," so named from the resemblance of its bark to the common cherry-tree. It is also called "sweet birch," because its young twigs, when crushed, give out a pleasant aromatic odour. Sometimes the name of "black birch," is given to this species. It is a tree of fifty or sixty feet in height, and its wood is much used in cabinet-work, as it is close-grained, of a beautiful reddish colour, and susceptible of a high polish.
The information regarding the birches of America was given by Lucien to his brothers, not at that time, but shortly afterward, when the three were engaged in felling one of these trees. Just then other matters occupied them, and they had only glanced, first at the canoe-birch and then at the other tree which Norman had pointed out. The latter was of a different genus. It belonged to the order _Coniferæ_, or cone-bearing trees, as was evident from the cone-shaped fruits that hung upon its branches, as well as from its needle-like evergreen leaves.
The cone-bearing trees of America are divided by botanists into three great sub-orders--the _Pines_, the _Cypresses_ and the _Yews_. Each of these includes several genera. By the "pine tribe" is meant all those trees known commonly by the names pine, spruce, fir, and larch: while the _Cupressinæ_, or cypress tribe, are the cypress proper, the cedars, the arbor-vitæ, and the junipers. The yew tribe has fewer genera or species; but the trees in America known as yews and hemlocks--of which there are several varieties--belong to it.
The pines cannot be termed trees of the tropics, yet do they grow in southern and warm countries. In the Carolinas, tar and turpentine, products of the pine, are two staple articles of exportation; and even under the equator itself, the high mountains are covered with pine-forests. But the pine is more especially the tree of a northern _sylva_. As you approach the Arctic circle, it becomes the characteristic tree. Then it appears in extensive forests, lending their picturesque shelter to the snowy desolation of the earth. One species of pine is the very last tree that disappears as the traveller, in approaching the pole, takes his leave of the limits of vegetation. This species is the "white spruce" the very one which, along with the birch-tree, had been pointed out by Norman to his companions.