Buttress root

Buttress roots, also known as plank roots or stilt roots, are large, wide roots on all sides of a shallowly rooted tree. Typically, they are found in nutrient-poor tropical forest soils that may not be very deep. They may prevent the tree from falling over, hence the name buttress.

Buttress roots of a Bay fig tree at South Coast Botanical Garden in Palos Verdes, California

Buttress roots of a colossal cotton-silk kapok in Lal Bagh gardens in Bangalore (Bengaluru), India

Buttresses are tension elements, being larger on the side away from the stress of asymmetrical canopies.^[1] The roots may intertwine with buttress roots from other trees and create an intricate mesh, which may help support trees surrounding it. They can grow up to 9 metres (30 ft) tall, spread for 30 m (98 ft) above the soil, and then continue another 30 metres horizontally below ground level. When the roots spread horizontally, they are able to cover a wider area for collecting nutrients. They stay near the upper soil layer because all the main nutrients are found there.^[2]

Notable and historic specimen trees with buttress roots

• Ceiba pentandra of Vieques, Puerto Rico
• Moreton Bay fig (Ficus macrophylla) in Queensland, Australia
• Jackfruit (Artocarpus heterophyllus), India
• Terminalia arjuna, India
• Koompassia excelsa, Southeast Asia

Gallery

• 
  Buttress roots. Jensen's Crossing near Cooktown, Australia. 1988
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  Buttress roots of Terminalia arjuna
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  A buttress root system provides structural support.
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  Buttress roots of an especially large Ceiba tree near shore of Amazon River, close to Iquitos, Peru
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  The large buttress roots of Koompassia excelsa