Plant stem

           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 buds which grow into one or more leaves, conifer cones, roots, other stems, or flowers (inflorescences); the internodes distance one node from another. The term "shoots" is often confused with "stems"; "shoots" generally refers to new fresh plant growth including both stems and other structures like leaves or flowers. In most plants stems are located above the soil surface but some plants have underground stems. A stem develops buds and shoots and usually grows above the ground. Inside the stem, materials move up and down the tissues of the transport system.Stems are often green.Stems have thin pipes to carry water around the plant.Stem consists of xylem and phloem tissue.

Stems have four main functions which are:^[1]

• Support for and the elevation of leaves, flowers and fruits. The stems keep the leaves in the light and provide a place for the plant to keep its flowers and fruits.
• Transport of fluids between the roots and the shoots in the xylem and phloem.
• Storage of nutrients.
• Production of new living tissue. The normal life span of plant cells is one to three years. Stems have cells called meristems that annually generate new living tissue.

Parts of a Stem

  

• Branch/lateral growth/side shoot

These different terms are all used to describe stems which come out of the main stem. Generally this growth is slightly slimmer than the main stem or ‘trunk’ of the plant.

• Node

Nodes are areas of growth. These parts of the stem contain a lot of cells which are called ‘meristematic‘; cells which actively divide to create lots of new cells. Nodes are where you will find buds, side shoots, leaves and flowers growing. Nodes are important when propagating plants by stem cuttings.

• Internode

This is the space between two nodes. It is the area which extends to give the stem more length and, therefore, the plant more height. It is also known as the ‘internodal’ area.

• Axillary bud

These are buds which form in the axils between a stem and a side shoot, or between a stem and a leaf. These buds may remain dormant or may develop into a side shoot, leaf or flower.

• Apical bud

This type of bud is found at the tip of stems and denotes a strongly meristematic area, ie an area where cells are actively dividing and, therefore, lengthening the stem. At these apical growth points there is a build up of a hormone called auxin, which controls the growth. The heightened levels of auxin at the tips of stems inhibits the axillary buds (this is called ‘apical dominance’) and is the reason why they often remain dormant. When we prune plants we remove the apical buds, which encourages more growth from the axillary buds. This is why plants often become more bushy with pruning .