The shadows of trees are possessed of certain properties. That of the walnut is baneful[2986] 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[2987] 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.[2988] 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.[2989] 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,[2990] 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[2991] 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.
CHAP. 19.—THE DROPPINGS OF WATER FROM THE LEAVES.
A very few words will suffice for the water that drops from the leaves of trees. In all those which are protected by a foliage so dense that the rain will not pass through, the drops are of a noxious nature.[2992] In our enquiries, therefore, into this subject it will be of the greatest consequence what will be the nature developed by each tree in the soil in which we are intending to plant it. Declivities, taken by themselves, require smaller[2993] intervals between the trees, and in localities that are exposed to the wind it is beneficial to plant them closer together. However, it is the olive that requires the largest intervals to be left, and on this point it is the opinion of Cato,[2994] with reference to Italy, that the very smallest interval ought to be twenty-five feet, and the largest thirty: this, however, varies according to the nature of the site. The olive is the largest[2995] of all the trees in Bætica: and in Africa—if, indeed, we may believe the authors who say so—there are many olive-trees that are known by the name of milliariæ,[2996] being so called from the weight of oil that they produce each year. Hence it is that Mago has prescribed an interval between these trees of no less than seventy-five feet every way, or of forty-five at the very lowest, when the soil happens to be meagre, hard, and exposed to the winds. There is no doubt, however, that Bætica reaps the most prolific harvests from between her olives.
It will be generally agreed that it is a most disgraceful piece of ignorance to lop away the branches more than is absolutely necessary in trees of vigorous growth, and so precipitate old age; as also, on the other hand, what is generally tantamount to an avowal of unskilfulness on the part of those who have planted them, to have to cut them down altogether. Nothing can reflect greater disgrace upon agriculturists than to have to undo what they have done, and it is therefore much the best to commit an error in leaving a superfluity of room.
CHAP. 20. (13.)—TREES WHICH GROW BUT SLOWLY: THOSE WHICH GROW WITH RAPIDITY.
Some trees are naturally slow in their growth; and those in particular which grow solely from seed[2997] and are long-lived. On the other hand, those that are short-lived grow with great rapidity, such as the fig, pomegranate, plum, apple, pear, myrtle, and willow, for instance; and yet these are the very first to display their productions, for they begin to bear at three years old, and make some show of it even before that period. The pear is the slowest in bearing of all the trees above enumerated. The cypirus,[2998] however, and the shrub known as the pseudo-cypirus[2999] are the earliest in coming to maturity, for they flower almost immediately, and then produce their seed. All trees will come to maturity more rapidly when the suckers are removed, and the nutrimental juices are thrown into the stock only.
CHAP. 21.—TREES PROPAGATED FROM LAYERS.
Nature, too, has taught us the art of reproduction from layers. The bramble, by reason of its thinness and the excessive length to which it grows, bends downwards, and throws the extremities of its branches into the earth; these immediately take root again, and would fill every place far and wide, were it not that the arts of cultivation put a check to it; so much so, indeed, that it would almost appear that men are born for nothing else but to take care of the earth. Hence it is, that a thing that is in itself most noxious and most baneful, has taught us the art of reproduction by layers and quicksets. The ivy, too, has a similar property.