Classification of Trees | Exogenous Trees and Endogenous Trees

The word timber is derived from an old English word timberian which means to build three terms are to be noted in connection with timber:

Converted Timber: Converted timber refers to wood that has been processed and transformed into a finished product, such as planks, beams, or plywood. The conversion process may involve cutting, planing, sawing, or shaping the wood to a specific size or shape. Converted timber is often used in construction, furniture, and other applications where a finished product is needed.

Rough Timber: Rough timber refers to wood that has not been processed or finished in any way. It is often cut directly from a tree and may still have the bark attached. Rough timber is typically sold by the board foot, and the buyer is responsible for processing the wood to their desired specifications. Rough timber is often used in construction and woodworking projects where a custom-sized piece of wood is needed.

Standing Timber: Standing timber refers to trees that are still growing in the forest. It is often measured in terms of board feet or cubic feet and is sold based on its species, size, and quality. Standing timber is typically harvested by logging companies, who then process the wood into rough or converted timber for sale to lumber mills or other buyers.


Trees play an essential role in our environment, and their classification is essential to understanding their physical and biological characteristics. In civil engineering, it is necessary to understand the different types of trees and their properties, especially when it comes to building structures with wood. One way to classify trees is based on their growth pattern, which can be divided into two main categories: exogenous trees and endogenous trees.

1. Exogenous Trees:

Exogenous trees are also known as dicotyledons. They are characterized by their ability to increase their diameter by producing new wood each year. Exogenous trees are the most common type of tree, and many species of hardwood, such as oak, maple, and mahogany, are exogenous trees.

Exogenous trees have two distinct layers of growth, namely the bark and the wood. The bark is the outermost layer of the tree, and it protects the tree from external factors such as insects, fungi, and weather conditions. The inner layer is the wood, which is the most important part of the tree for construction purposes. The wood provides the strength and stability necessary to support buildings and other structures.

2. Endogenous Trees:

Endogenous trees are also known as monocotyledons. They are characterized by their ability to increase their diameter by adding new layers of growth within the existing tissue. Endogenous trees are less common than exogenous trees and are typically found in tropical regions.

Endogenous trees do not have a distinct layer of bark and wood, but rather, they have a series of vascular bundles distributed throughout the stem. These vascular bundles provide the structural support necessary to hold up the tree and distribute nutrients throughout the plant.


In conclusion, understanding the classification of trees is essential in civil engineering, particularly in designing and building structures with wood. Exogenous trees, also known as dicotyledons, are the most common type of tree and are characterized by their two distinct layers of growth: bark and wood. Endogenous trees, also known as monocotyledons, are less common and are characterized by their vascular bundles distributed throughout the stem. Knowing the properties of each type of tree is essential for choosing the right wood for the job and ensuring the safety and longevity of the structure.

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