Nothing dies harder than generally accepted delusions, particularly those regarding plant lore, and of all such incorrect impressions the one that a potato is a root, is the hardiest and most difficult to kill. Yet, the “eyes” of a potato give it away if one stops for a moment to reflect that the eyes are only buds and buds grow only on stems. That is one of the chief uses of stems—to support in the air the leaves and flowers that come from its buds, and no matter if the stem, as in the potato and many other plants, be ever so deeply buried their true stem nature cannot be mistaken. Sometimes these underground stems are not thickened but lengthened out, in which case, notably in common garden iris, they are called rootstocks. Again, these buried stems may be swollen, as in the potato, when they are known as tubers. Onions and the jack-in-the-pulpit bear still other kinds of underground stems, and there are many more, but they cannot be mistaken for roots, for it will be seen from Figures 6-9 that on their under sides they bear roots themselves. Besides this they bear buds or shoots, which no true root ever does.
Just inside the calyx is what most people call the “flower,” which is really composed of more highly colored sepals, but which we call petals (Figure 39A). Where these are joined together the collection, which forms tubular flowers like the lily of the valley, is called a corolla. It is, of course, the petals or corollas of flowering plants that give our landscapes their greatest beauty, their most gorgeous coloring. While this from one point of view amply justifies a prodigal nature in strewing the earth with beautiful flowers, the true value of the color to the plant is in quite other directions, which will be explained a little later.