The main, often long or slender part of a plant that usually grows upward above the ground and supports other parts, such as branches and leaves. Plants have evolved a number of tissue arrangements in the stem. Seedless vascular plants (such as mosses and ferns) have primary vascular tissue in an inner core, a cylindrical ring, or individual strands scattered amid the ground tissue. In eudicots, magnoliids, and conifers, the stem develops a continuous cylindrical layer or a ring of separate bundles of vascular tissue (including secondary vascular tissue) embedded in the ground tissue. In monocots and some herbaceous eudicots, individual strands of primary vascular tissue are scattered in the ground tissue.
A slender stalk supporting or connecting another plant part, such as a leaf or flower.