Grape vines have fibrous bark. Stems of some plants occur in a modified form to accommodate additional functions. A corm looks very much like a bulb but is composed of stem tissue, as opposed to a bulb, which is made up of leaf tissue. Gladioli, crocuses, and freesias are corms. A flattened, green stem with small, scale-like leaves.
Phylloclades look like leaves and even function as leaves.
But morphologically, they are stems. A horizontal stem found underground. A rhizome can be distinguished from a root by the presence of nodes on the rhizome ends. A runner is very similar to a stolon . Both structures allow the plant to move within its environment.