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.
Stems above ground, which is the most usual form for them, are of many kinds, all serving the purpose of support to the leaves and flowers, and as a means of carrying sap from the roots or underground stems to the upper part of the plant, and also to carry certain foods to the roots from the leaves, of which more anon. In the case of herbs, like goldenrod or daisy, the stem may be apparently all pith on the inside, with only a thin outer coating of harder substance, not unlike bark, but usually green. If we examine the cut-off trunk of a tree, a quite