Kids Research Express

Stem, portion of vascular plants that commonly bears leaves and buds. It usually is aerial, upright, and elongate, but may be highly modified in structure. Subterranean stems include the rhizomes of the iris and the runners of the strawberry; the potato is a portion of an underground stem. Some plants, such as the century plant, have very short stems that bear a dense cluster of leaves. Those points on the stem at which leaves or buds arise are called nodes, and the regions of the stem between the nodes are known as internodes. The chief functions of stems are the production and support of leaves and reproductive structures, conduction of water and nutrients and food storage. In some plants, such as cactus, stems also have the specialized functions of storing water and manufacturing food. Conducting tissues within plant stems are arranged in columns called vascular bundles. These bundles are composed of xylem , which conducts water up the stem, and of phloem , which transports sugars p

The body of a vascular plant is organized into three general kinds of organs: roots, stems, and leaves. These organs all contain the three kinds of tissue systems mentioned above, but they differ in the way the cells are specialized to carry out different functions. Roots The function of roots is to anchor the plant to its substrate and to absorb water and minerals. Thus, roots are generally found underground and grow downward, or in the direction of gravity. Unlike stems, they have no leaves or nodes. The epidermis is just behind the growing tip of roots and is covered with root hairs, which are outgrowths of the epidermal cells. The root hairs increase the surface area of the roots and serve as the surface through which water and nutrients are absorbed. Internally, roots consist largely of xylem and phloem, although many are highly modified to carry out specialized functions. Thus, some roots are important food and storage organs—for example, beets, carrots, and radishes. Suc