You know that the root does the drinking for the plant; and only the newest parts of the root, the fresh root tips, are really good for work of this sort. You remember that the earth food is carried up the stem to the leaves in a watery broth; and that if the water supply should give out, the new plant cells would not get the broth which helps them to grow, and to put out other cells, and so to build up the plant. Now, as only the new root branches, near their tips, are able to drink, if the water should leak through the earth in equal quantities everywhere, much of it would be wasted; but when this water is collected in certain spots within reach of the new root branches, there is good reason to believe that these will be able to satisfy their thirst. By the shedding of the rain from the tips of the spreading branches above, the water is collected in a ring, and so sinks into the earth; and the root branches below spread out in just the same direction as the tree branches above, till they find what they need, and drink their fill. [Illustration: FIG. 138] So by the way in which a tree sheds the rain, you can tell just where its root branches reach out underground. In smaller plants you see much the same thing. Fig. 138 shows a plant called the _Caladium_. You can see that the raindrops must roll outward down these leaves, and fall upon the earth just above the tips of the root branches. Fig. 139 shows you the rhubarb plant. This has quite a different sort of root. Now, if the rhubarb leaves were like those of the _Caladium_, unless the rhubarb root-branches changed their direction, these root-branches would grow very thirsty indeed. [Illustration: FIG. 139] But as it is, the water pours down these leaves toward the center of the plant, and reaches the ground almost directly over the straight, fleshy root, with its downward-growing branches; and we see that these root-branches are watered by the leaves above just as carefully as are those of the _Caladium_. By knowing one thing about a plant, often you can guess that another thing is so. You understand now that when the leaves of a plant shed rain water after the fashion of the _Caladium_, the chances are that its root-branches spread out as far as the drip of the water; and that the root of the rhubarb points almost straight downward, is told you by the drip of water from the rhubarb leaves. LEAF VEINS Some time ago you learned that from the stem of a plant you could guess the number of seed leaves which it brought into the world, and that in the same way from the seed leaves you could guess what kind of a stem it would build up. From the way in which a leaf is veined you can guess both of these things. You can guess what sort of a stem belongs to the plant, and with how many seed leaves it began life. When the little veins run in and out, forming a sort of network, we say that the leaf is “net-veined.” [Illustration: FIG. 140] [Illustration: FIG. 141]