A Walk on the Wild Side: “Walking Palm Trees” Really Stride Through The Rainforests

From John Wyndham’s terrifying Triffids and the bloodthirsty Audrey II from Little Shop of Horrors, to the wise and ancient Ents of J. R. R. Tolkein’s Lord of the Rings, speculative fiction is full of wandering vegetation. But could a tree actually pick up its roots and take a walk? That’s the lore surrounding the Walking Palm of Latin America.

The Local Tree

Socratea exorrhiza, or cashapona, to give it its local name, is a species of palm tree. It’s found in the rainforests of Central and South America. Each palm has a remarkable bundle of stilt-like roots at its base, sometimes extending a long way from the tree itself. It really looks as if the palm could scuttle away at any moment.

The Cashapona: A Legend With Legs?

A few feet from the ground, the trunk of the cashapona palm divides into a spreading mass of stilt-like roots that radiate out from the base of the palm. Part of their Latin name, “exorrhiza”, comes from this unusual growth pattern. It means “outside roots.” They look a lot like an old-fashioned broomstick – or a collection of woody legs.

These eye-catching roots make the cashapona a star attraction for anyone touring the rainforests. They’re both beautiful and baffling. Why do the palm’s roots extend so far above the ground? How come they’re not buried in the soil, like other trees? How does this benefit the plant? It’s no wonder that so many legends have sprung up around the palm.

Fascinating Ideas on Function

The function of the exposed roots of the cashapona have been debated, not just because of the legends that have sprung up around their potential “abilities.” The unusual structure of the roots has led scientists to wonder if they were initially a development in order to allow the tree to grow in swampy areas, where there might be less stability in the ground.

This is an interesting thought, given that the cashapona is native to rainforests in central and South America. However, there is no evidence to suggest that the root system was adaptive to flooding, leading scientists to theorize on other root causes.

More Thoughts on Evolutionary Function

Other theories regarding the function of the stilt roots were a potential of avoiding debris on the ground such as fallen trees. The taller roots would allow the trees to still connect to the ground and soak up nutrients, while avoiding some of the obstructions on the ground.

Another theory is that the taller roots allow the tree trunk itself to grow taller, and more stable towards the sky. Trees that are taller typically have a larger trunk for stability, and the unique root system of the cashapona might mitigate that particular evolutionary necessity. More than anything, though, people like to theorize about the roots allowing the trees to “walk” around, moving from place to place.

A Palm Tree On The Run

Rainforest guides love to regale tourists with stories about the walking palm. The cashapona is said to wander about the forest (always when nobody is watching, of course). The idea of a palm tree walking through the forest might seem like the stuff of fiction. Tales of stealthily stalking palm trees are certainly entertaining but they’re just stories… aren’t they?

Some scientists did put forward hypotheses that are not too dissimilar to the legends about walking palm trees that hike through the forest unseen. In an attempt to explain why the walking palm’s long roots grow the way they do, scientists have come up with some ideas. Maybe the palms were “walking” after all – just very, very slowly.

Is This Palm Walking On Sunshine?

The explanation went like this: palm trees need sun and don’t thrive as well if there’s too much shade. In order to get to a sunnier spot, it might be possible for the chashapona to grow more roots on the sunny side and allow roots in the shade to shrivel up and detach from the ground.

The tree’s trunk would gradually align with the new root pattern. In this way, the cashapona could theoretically ‘walk” from one place to another. They wouldn’t be striding across the landscape like an army of Ents on the march, but they would be moving little by little. It’s a reasonable hypothesis which could explain many of the walking palm’s oddities.

Walking Away From Disaster: A Rival Theory

This wasn’t the only hypothesis put forward to explain the walking palm’s stilt-like roots and reputation for wandering. In 1980, anthropologist John H. Bodley came up with another possible answer. He suggested that the long and exposed root system might be an adaptation that let the palm survive being knocked down by falling trees or branches from above.

In Bodley’s model, a cashapona sapling that got knocked flat by falling vegetation could grow a new trunk from its surviving roots. This brand new tree would be some distance away from the original sport where it germinated but would use the same root system, effectively walking away from trouble. It’s a convincing idea – but is it true?

Quick, Follow That Tree!

If S. exorrhiza can really walk, you might be asking yourself, how come nobody has ever seen it happen? Well, at least one person claims to have witnessed the process. Bratislavan paleobiologist Peter Vrsansky recounted seeing the palms “walk” in his writings, stating that he’d seen this happen when the soil around the plant erodes.

In Vrsansky’s account, eroding soil triggers the cashapona to grow new roots that seek out a more stable footing for the palm. Once these roots hit solid ground, they dig in and slowly anchor the tree to the new spot. The exposed roots on the other side wither away, meaning that the tree has shifted its position over time.

Pinning Down the Walking Palm

Someone who disputes these hypotheses is biologist Gerardo Avalos. Dr. Avalos is a professor of tropical ecology at the University of Costa Rica and is a world-class expert on the cashapona palm. In his 2005 analysis of S. exorrhizoma and its remarkable structure, he attempted to root out the legend of the walking palm once and for all.

Published in Biotropica: The Journal of Biology and Conservation, this analysis stated categorically that the walking palm doesn’t really walk. Some of the roots will naturally die off over time and there might be more dead roots on one side than another. The palm as a whole, however, stays put and doesn’t travel.

A Step Too Far

In their article “Stilt Root Structure in the Neotropical Palms Iriartea deltoidea and Socratea exorrhiza“, Avalos and his co-authors sought to debunk the walking palm legends by researching the palms themselves and taking a look at the details of the stories. Their conclusions might be disappointing initially but are still very interesting if you’re curious about these highly unusual plants.

Some accounts have claimed that the walking palm can travel 66 feet (20 meters) in a single year. If that was true, Avalos points out, someone would definitely have noticed the migrating trees. So you won’t find Treebeard wandering the rainforest – but you will find the cashapona. That’s pretty cool too.

“Walking” Isn’t the Only Thing These Plants Do

The roots of the cashapona aren’t the only thing that make the tree unique, either. Cashapona leaves have been found to be thicker when they spend the majority of the time in the sun versus the majority of the time in the shade, allowing them to have more trichomes and stomata than their shaded counterparts.

The cashapona is also the host plant for many different species of epyphite. Epyphites are plant or plant-like organisms that live on other organisms, often host plants, and take advantage of the moisture, air, and nutrients that surround the host plant to grow.

Symbiotic Relationships are Very Important

Symbiotic relationships such as those between epyphites and their host plants are common in the plant and animal kingdoms. Whales have whale barnacles, clownfish have the anemone that they live in. Animals and plants have adapted to other organisms in myriad mutually beneficial ways, and the cashapona is no different.

The cashapona is host to dozens of different species of epyphites. One study of 118 different trees found 66 species of plant living off the trees, from fifteen different plant families. Many of these were mosses, but there were species of vascular plants found on them as well. It’s one example of nature finding a way in the vast experience of the natural world.

A Greater Purpose Beyond Sustaining the Plant

The cashapona is an unusual plant, and the ongoing curiosity regarding its unusual roots and their purpose is only one example of the ways that nature continues to stump and amaze scientists. While the story of the plants walking is merely entertainment value for tourists, it does point to a greater curiosity from humans about the unknowable nature of the universe.

We may never know definitively the purpose of the cashapona’s roots, but that’s okay. The fact that they exist at all can be a mere wonder, a curiosity. As long as we continue to dream and question and pursue knowledge in the face of the unfathomable, though, then mysteries like the cashapona’s roots can continue to serve a greater purpose.