A stolon is much like a rootstock, but it grows along the surface of the ground, sending roots down and stems up at intervals. A runner , like that of the strawberry plant, is a type of stolon. A corm is a short, thick, vertical underground stem that survives from one season to the next in a dormant state. The second season it produces one or more aerial stems and also one or more new corms. The new corms store food produced by the growing plant and then go through the next dormant period to produce their own plants and corms the following season.
Bulbs are different from corms, although the latter are often called bulbs.
The portion of the plant that everyone recognizes as the stem is more precisely called the aerial stem . Its main function is to bear leaves, the stem with its leaves being called the shoot. In addition to bearing leaves, the aerial stem performs the vital functions of transporting water and minerals up from the roots to the leaves and transporting manufactured food substances as they are distributed to all parts of the plant for use or storage. Radical leaves grow directly from a non-aerial stem. See the accompanying illustration and the definitions in the glossary of botanical terms for explanations of the various shapes and forms of leaves.