Roots of the walking palm, Wilson Botanical Garden, Costa Rica, 2 Feb 2017 (photo by Kate St. John)
Here’s a tree whose roots are taller than a man and are said to “walk” 20 meters a year(*). Really?
The walking palm (Socratea exorrhiza) is native to Central and South America where its narrow trunk grows 50-80 feet tall with stilt roots up to eight feet high. The walking palms at Wilson Botanical Gardens, Costa Rica were so tall that I couldn’t get their tops in the viewfinder.
Walking palm trees, Wilson Botanical Garden, Costa Rica, 2 Feb 2017 (photo by Kate St. John)
The tree’s claim to fame, repeated by local guides and the BBC, is that it can “walk” more than 65 feet a year by throwing out new roots to one side, leaning toward the new roots and abandoning those on the trailing edge.
But this is not true.
Reality Check: 20 meters per year is 65.6 feet, the height of 6 story building. At 5.5 feet per month it’s a distance that’s easy to see and hard to ignore. You would notice that the plant is not where you left it!
Scientists have measured over and over and the walking palm never walks. But they are puzzled why it has enormous stilt roots. It occurred to me that an old theory about the roots may have spawned the walking legend.
In 1980, John Bodley and Foley C. Benson proposed that the tree has stilts so it can recover when downed by another tree, as shown in the diagram below.
1980: How the stilt roots of Socratea exhorriza allow it to right itself (from a paper by John Bodley & Foley C. Benson, March 1980, via Wikimedia Commons)
Tree #4 took root from the crown that hit the ground. Its distance from the old root system is the height of the old tree. The trees average 65 feet tall. Hmmmm!
Other fallen trees can sprout roots, too, and later studies disputed Bodley & Benson’s theory, yet none have solved the underlying mystery. Why does Socratea exorrhiza have such long stilts? No one knows for sure.
Meanwhile, at Wilson Botanical Gardens the walking palms stay rooted where the Wilsons planted them. Otherwise they’d be half a mile away by now.
(*) Meters or centimeters? See the comments here!
(photos by Kate St. John. Diagram from Wikimedia Commons; click on the image to see the original)