Heartwood and Sapwood – Class 11 | Chapter – 6 | Short Notes Series PDF
Heartwood and Sapwood: Heartwood and sapwood are the two areas in a cross section of a woody stem. Both types of wood perform a critical function in a tree. The main difference between heartwood and sapwood is that heartwood is the dead, inner wood whereas sapwood is the outermost portion of a wood that is living.
Heartwood
Heartwood or durame is the inner portion of the woody stem, containing clogged secondary xylem. Heartwood formation is genetically programmed.
With growth, the stem increases its diameter, forming new xylem and phloem. Therefore, the most centered and ancient xylem becomes useless.
Then, that part of the xylem becomes a part of an essential function for the tree. For this, the cells in the center of the trunk die and chemical compounds accumulate in them. Some of these compounds are resins, terpenes, and phenols.
So it gives the heart a dark color. In addition, this offers resistance to decomposition and the ability to prevent insects and fungal infections. In addition, this allows for functional change. Therefore, the main function of the heartwood is to provide structural support to the tree.
Sapwood
Alburnum or laburnum is the initial wood form of any tree. It occurs from a thin layer of cells under the bark, called the vascular cambium, which produces wood cells for the interior and bark cells for the exterior.
Therefore, sapwood always contains newly formed cells that are alive. In addition, as these cells do not contain chemical compounds deposited as resins, the sapwood is lighter in color and has a soft texture.
However, it is more prone to attacks by fungi and insects. The main function of sapwood is to transport water and nutrients throughout the plant.
Collectively, water and nutrients are known as sap. In addition, the sapwood cells also provide structural support to the tree.
Difference between Heartwood and Sapwood
| Heartwood occurs in the central portion of an old stem. | Sapwood occurs in the peripheral (outer) portion of an old stem. |
| Cells are comparatively older. | Cells are comparatively younger. |
| Also called as ‘Duramen’ | Also called as ‘Alburnum’ |
| Heartwood is dark colured | Sapwood is light coloured. |
| It is the dead and nonfunctional part of the secondary xylem. | It is the living and functional part of the secondary xylem. |
| The lumens of vessels and tracheids are plugged due to tyloses formation. | Vessel and tracheid are not plugged. No tyloses formation. |
| Cells store many ergastic substances such as resins and tannins. | Cells do not store any ergastic substances. |
| Cells store many ergastic substances such as resins and tannins. Heartwood is heavier. |
Sapwood is light in weight. |
| Heartwood is the durable wood. | Sapwood is not a durable wood. |
| Heartwood is suitable for making furniture | Sapwood is not suitable for making furniture. |
| Wood is resistant to insect and fungal attacks | Wood is susceptible to insect and fungal attacks. |
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