Do you know that a plant will not grow without leaves? And it will not bear fruit, and will die early, if it has too many leaves? The plant suckles moisture from the earth and the sun draws that moisture away again, through the tiny and innumerable pores of its leaves. So the healthy existence of a plant depends upon the living stream of moisture which must continually flow through the plant. Simply to flow into it is not enough; and when the stem is severed we quickly see the results of too much flowing out, with nothing flowing in. Death is the inevitable result of. any continued disturbance of that steady flow of sap up from the earth, through the plant, and on out again into the atmosphere.
Of course, a sterile earth can give little sap to the plant and it soon dies; and the more fervently the sun kisses it and draws upon it the more quickly the plant expires. On the other hand, if the leaves are plucked, so that there are not pores enough for the sun to suck the sap through, the plant must die.
But plants are wonderfully intelligent little things, and full of ingenious contrivances for regulating supply and demand in such a way as to maintain the equilibrium which means health. The.. little wild things are wiser than we tame beings, in looking out well for number one. The cactus grows thick, fleshy leaves where it stores up moisture for use in the long, hot seasons when supply is small and demand great. And it glazes its leaves so that the sun cannot draw from it all the moisture it would. Many plants and trees glaze the entire upper sides of their leaves, so that the sun may draw from the shaded side only, where he cannot kiss so fervently. Some trees turn only the edges of their leaves toward the sun. And a great many refuse to grow wide. leaves, and the drier the soil the narrower the leaves, even in trees of the same family. All plants show this intelligence.