A stem is one of two main structural axes of a vascular plant, the other being the root. The stem is normally divided into nodes and internodes:
The nodes hold one or more leaves, as well as buds which can grow into branches (with leaves, conifer cones, or inflorescences (flowers)). Adventitious roots may also be produced from the nodes.The internodes distance one node from another.
The plant stem including its outermost bark has multiple uses ranging from logs, firewood, lumber, source of pulp for paper making, source of food, fiber, medicine, latex, tannin, dye and many more. It is also the most widely used part for asexual or vegetative plant propagation.
In plant growth and development, the plant stem performs the following functions:
- It supports the leaves, flowers and fruits and connects them with the roots. In trees and shrubs, the main stem or trunk provides a strong columnar structure from which branches are attached, raising the leaves upward to be exposed more fully to the sun.
- It conducts water, nutrients and the products of photosynthesis to and from roots and leaves. It accommodates the transport system which is necessary for the vertical and lateral movement of water and sap within the plant body.
- It helps store water, as in cacti, and the products of photosynthesis, as in the trunk of sago palm (Metroxylon sagu) and sweet palm (Arenga pinnata) which store large stock of starch;
- Young green stem also performs a minor role in the production of food through the process of photosynthesis, but in some species (e.g. cactus) the stem is the chief photosynthesizing organ.
- The plant stem serves as a means of asexual reproduction in many plant species