Since young we are being taught that plants are living organisms that are stationary unlike humans and animals that move around actively. However, nature surprises again with an extraordinary plant that can walk. The plant is Socratia Exorhiza, a palm tree known as a walking plant. It is said that the tree moves around 20 metres every year. Socratia is a genus of five species of palms found in tropical Central America and South America. This tree could be found in Nicaragua, Costa Rica and Panama. How does this tree exactly walk?
This tree walks because of their unique root system which is a stilt root similar to mangrove. It develops a set of aerial roots where it does not have a complete underground root system unlike other plants. The roots of this tree grow outwards from the tree and over time as soil erodes, some of the roots die off. The new roots will grow one side and let go of its roots at the opposite side. That is how the tree is displaced from its old position to a new position since the tree follows the direction of new roots. Various theories have been proposed on the function of stilt root. Stilt root serves various functions including rapid vertical growth and enhanced mechanical stability. It can reach up to 25 metres of height and 16 cm of stem diameters.
You might be curious why this plant needs to walk around the forest just to meet the Sun. Yes, in a tropical forest light is a limiting factor and this plant has to move until it reaches a sunny area for its survival. Palm trees are found abundantly in rainforest and they are also known as iconic tropical forest plants. Competition for sunlight among plants in tropical rainforests is a tight race. Tropical rainforest has dense vegetation which forms three different layers, the canopy, the understory and the ground layer. Although tropical forests receive 12 hours of sunlight on a daily basis, less than 2% of sunlight reaches the ground. The soil is always shaded because tall trees create the canopy and the understory layer prevents sunlight from reaching the ground.
Plant survival in a tropical rainforest depends on the plants ability to tolerate constant shade or adapt its own strategy to reach sunlight. Thus, Socratia’s strategy to attain sunlight is by walking around the forest. Since the plant has to be competitive enough to obtain sunlight the root system allows the tree to grow higher and longer rather than getting thick trunks so it can attain canopy growth. Thus, the tree spends less energy in developing its trunk and underground root system unlike other plants.
Although Socratia does not have an underground root system, it gets good mechanical stability from its aerial-like root. Aerial roots are roots above the ground and provide greater support and stability for the stem. Aerial roots could perform multiple functions such as air exchange, propagation, stability and nourishment. Some believe that stilt roots allow the tree to be more stable in swampy areas. However, scientists continue to study and debate about the behaviour of this walking plant but none of the theories has been confirmed and it remains as a strange miracle from nature.