The shadows of trees are possessed of certain properties. That of the walnut is baneful[1] and injurious to man, in whom it is productive of head-ache, and it is equally noxious to everything that grows in its vicinity. The shadow, too, of the pine has the effect of killing[2] the grass beneath it; but in both of these trees the foliage presents an effectual resistance to the winds, while, at the same time, the vine is destitute of such protection.[3] The drops of water that fall from the pine, the quercus, and the holm-oak are extremely heavy, but from the cypress none fall; the shadow, too, thrown by this last tree is extremely small, its foliage being densely packed.[4] The shadow of the fig, although widely spread, is but light, for which reason it is allowed to be planted among vines. The shadow of the elm is refreshing and even nutrimental to whatever it may happen to cover; though, in the opinion of Atticus, this tree is one of the most injurious of them all; and, indeed, I have no doubt that such may be the case when the branches are allowed to become too long; but at the same time I am of opinion that when they are kept short it can be productive of no possible harm. The plane also gives a very pleasant shade,[5] though somewhat dense: but in this case we must look more to the luxuriant softness of the grass beneath it than the warmth of the sun; for there is no tree that forms a more verdant couch on which to recline.

The poplar[6] gives no shade whatever, in consequence of the incessant quivering of its leaves: while that of the alder is very dense, but remarkably nutritive to plants. The vine affords sufficient shade for its wants, the leaf being always in motion, and from its repeated movement tempering the heat of the sun with the shadow that it affords; at the same time too it serves as an effectual protection against heavy rains. In nearly all trees the shade is thin, where the footstalks of the leaves are long.

This branch of knowledge is one by no means to be despised or deserving to be placed in the lowest rank, for in the case of every variety of plant the shade is found to act either as a kind nurse or a harsh step-mother. There is no doubt that the shadow of the walnut, the pine, the pitch-tree, and the fir is poisonous to everything it may chance to light upon.