§ 2. A child's division of plants is into "trees and flowers." If, however, we were to take him in spring, after he had gathered his lapful of daisies, from the lawn into the orchard, and ask him how he would call those wreaths of richer floret, whose frail petals tossed their foam of promise between him and the sky, he would at once see the need of some intermediate name, and call them, perhaps, "tree-flowers." If, then, we took him to a birch-wood, and showed him that catkins were flowers, as well as cherry-blossoms, he might, with a little help, reach so far as to divide all flowers into two classes; one, those that grew on ground; and another, those that grew on trees. The botanist might smile at such a division; but an artist would not. To him, as the child, there is something specific and distinctive in those rough trunks that carry the higher flowers. To him, it makes the main difference between one plant and another, whether it is to tell as a light upon the ground, or as a shade upon the sky. And if, after this, we asked for a little help from the botanist, and he were to lead us, leaving the blossoms, to look more carefully at leaves and buds, we should find ourselves able in some sort to justify, even to him, our childish classification. For our present purposes, justifiable or not, it is the most suggestive and convenient. Plants are, indeed, broadly referable to two great classes. The first we may, perhaps, not inexpediently call TENTED PLANTS. They live in encampments, on the ground, as lilies; or on surfaces of rock, or stems of other plants, as lichens and mosses. They live--some for a year, some for many years, some for myriads of years; but, perishing, they pass as the tented Arab passes; they leave _no memorials of themselves_, except the seed, or bulb, or root which is to perpetuate the race. § 3. The other great class of plants we may perhaps best call BUILDING PLANTS. These will not live on the ground, but eagerly raise edifices above it. Each works hard with solemn forethought all its life. Perishing, it leaves its work in the form which will be most useful to its successors--its own monument, and their inheritance. These architectural edifices we call "Trees."