Medullary ray (botany)

Botanical structure in plant stems

Medullary ray (botany)

Cross-section of an oak showing medullary rays

In botany, a medullary ray is a radial sheet or ribbon extending vertically through the tissues of the stem of a plant. These rays are primarily composed of parenchyma cells and are crucial for the transport of nutrients and water, as well as for the storage of food and other substances.

Structure

Medullary rays are found in the vascular tissue of dicotyledonous plants. They extend from the pith at the center of the stem to the cortex near the outer edge. The rays are composed of living cells that are capable of storing and transporting nutrients.

Function

The primary function of medullary rays is to facilitate the radial transport of nutrients and water between the xylem and phloem. They also play a role in the storage of starch, lipids, and other substances. Additionally, medullary rays contribute to the structural integrity of the plant by providing support and stability.

Importance in Wood

In wood, medullary rays are visible as lines or bands that run perpendicular to the growth rings. They are particularly prominent in certain species, such as oak and maple, where they contribute to the aesthetic appearance of the wood. The pattern and size of the medullary rays can affect the texture and grain of the wood, making them an important consideration in woodworking and furniture design.

Related pages

• Xylem
• Phloem
• Parenchyma
• Vascular tissue
• Dicotyledon