Plant Structure: The Stem

Stem Functions and Characteristics

• The stem is the organ that holds the plant's structure, including leaves, flowers, and fruits.
• It carries water and minerals from the roots to the leaves.
• Stems have various jobs, including determining the size and shape of a plant.

Support and Transport

• Stems support the leaves, holding them in the most efficient position to collect sunlight.
• They move water, minerals, and manufactured food throughout the plant through a process called translocation.

Food Production and Storage

• Green stems can produce food through photosynthesis, which is important in plants with no leaves or small leaves.
• Stems can store food manufactured by the plant.

Types of Stems

Herbaceous Stems

• Have soft, green stems and naked buds.
• Covered with epidermis.
• Grow to a small diameter.
• Live only for one season (annual).
• Have primary tissues only.

Woody Stems

• Have brown cover and are chiefly covered by scales.
• Covered with periderm or bark.
• Grow to a considerable diameter.
• Live year after year (perennial).
• Have secondary tissues.

Stem Components

• A node is a point on the stem where leaves or buds arise.
• The portion between two successive nodes is the internode.
• A bud is an embryonic stem with potential for further plant growth.
• Types of buds: Axillary Bud and Terminal Bud.

Leaf Components

• A petiole is a stalk that attaches the leaf blade to the stem.
• Stipules are paired leaf-like appendages at the base of the petiole.
• Leaf scars are scars left by a fallen leaf.
• Bundle scars are scars that mark the location of the water-conducting tissue within the leaf scars.
• Lenticels are dark spots or elevations that allow gas exchange in the stem.