Heartwood – Definition & Detailed Explanation – Identification and Classification Of Trees Glossary

What is Heartwood?

Heartwood is the innermost part of a tree trunk or branch, surrounded by sapwood. It is a dense, dark-colored wood that is no longer active in the tree’s transport of water and nutrients. While sapwood is responsible for conducting water and nutrients throughout the tree, heartwood serves a different purpose within the tree’s structure.

How is Heartwood Formed?

Heartwood is formed as a tree ages and grows. As new layers of sapwood are added to the tree’s circumference, the innermost layers of sapwood become inactive and transform into heartwood. This process is known as heartwood formation. The transformation occurs as the tree deposits various substances, such as resins, gums, and tannins, into the cells of the sapwood, causing them to become darker and denser.

What is the Function of Heartwood?

The primary function of heartwood is to provide structural support and strength to the tree. Due to its dense and durable nature, heartwood is more resistant to decay and insect damage compared to sapwood. It also helps the tree to withstand environmental stresses, such as wind, snow, and ice. Additionally, heartwood may store waste materials and toxins that the tree has accumulated over time, preventing them from spreading to the rest of the tree.

How to Identify Heartwood in Trees?

Identifying heartwood in trees can be done by examining the color and texture of the wood. Heartwood is typically darker in color than sapwood, ranging from light brown to deep red or even black. It also tends to have a denser and harder texture compared to the softer and lighter sapwood. In some cases, the transition between sapwood and heartwood may be clearly visible as a distinct boundary within the tree trunk or branch.

What are the Different Types of Heartwood?

There are several different types of heartwood found in trees, each with its unique characteristics and properties. Some common types of heartwood include:

1. Red Heartwood: Red heartwood is characterized by its deep red color, which is often caused by the presence of tannins and other pigments in the wood. It is commonly found in species such as mahogany, cedar, and cherry.

2. Yellow Heartwood: Yellow heartwood has a golden-yellow hue and is often found in species like pine, oak, and teak. The coloration is due to the presence of natural oils and resins in the wood.

3. Black Heartwood: Black heartwood is a rare and highly prized type of heartwood known for its dark black color. It is found in species such as ebony and black walnut and is valued for its unique appearance and durability.

How Does Heartwood Differ from Sapwood?

Heartwood and sapwood differ in several key ways, including their color, texture, and function within the tree. While heartwood is darker in color and denser in texture, sapwood is lighter in color and softer in texture. Heartwood is inactive in the tree’s transport system, while sapwood is responsible for conducting water and nutrients throughout the tree. Additionally, heartwood is more resistant to decay and insect damage, making it a valuable component of the tree’s structure.