Buttress root — also known as a plank root or stilt root — is a type of large, wide root that grows on all sides of a shallowly rooted tree, typically found in nutrient-poor tropical forest soils. These roots extend above ground from the base of the trunk, forming plank-like or flange-shaped structures that provide mechanical support and help prevent the tree from falling over, hence the name "buttress."
Characteristics
- Structure: Buttress roots are tension elements, being larger on the side away from the stress of asymmetrical canopies. They can grow up to 9 metres (30 ft) tall and spread for 30 metres (98 ft) above the soil, continuing another 30 metres horizontally below ground level.
- Function: They stabilize trees in shallow, nutrient-poor, or waterlogged soils by spreading the tree's weight over a wider area. By staying near the upper soil layer, they also allow the tree to collect nutrients from the richest part of the soil.
- Intertwining: The roots may intertwine with buttress roots from other trees, creating an intricate mesh that may help support surrounding trees.
Occurrence
Buttress roots are common in many tropical trees, including certain figs (Ficus), kapok (Ceiba pentandra), jackfruit (Artocarpus heterophyllus), Terminalia arjuna, and Koompassia excelsa. They are an adaptation to the shallow, nutrient-poor soils typical of tropical rainforest environments.
Botanical Classification
In botanical terminology, a buttress root is a form of prop root that is asymmetrically thickened to give a plank-like outgrowth on the upper side, providing extra support for the tree.
