The part of the plant axis that is usually above ground and bears the leaves, reproductive parts, and buds. The terms shoot and stem are virtually synonymous except that an underground stem, such as a corm or rhizome, would rarely be described as a shoot. The vascular system of the stem conducts water and nutrients from the roots to the aerial parts and photosynthates from the leaves to any regions where they are needed. The vascular tissues of higher plant stems are usually arranged as a cylinder (as in most dicotyledons) or dispersed irregularly through the cortex (as in monocotyledons). The stem is usually elongated and branched so the leaves are separated and displayed to best advantage and the flowers are in suitable positions for pollination. There may be one main stem or trunk with side branches, as in many trees, or a number of equally prominent stems. Compare root. |
