All stems vary in shape and size; in addition, some plants have modified stems. For example, strawberry plants have runners (stolons) that are horizontal stems growing along the surface of the ground. Iris plants also have horizontal stems (rhizomes). Most stems have nodes and internodes: The nodes are the points where the leaves are attached to the stem, while the internodes are the parts of the stem between the nodes. The four main functions of stems are: 1) to support leaves; 2) produce carbohydrates; 3) store materials such as water and starch; and 4) transport water and solutes between roots and leaves and also provide the link between the water and dissolved nutrients of the soil and the leaves.