As They Grow, Baobab Trees Hollow Themselves Out From The Inside

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The baobab tree is one of nature’s weirder creations. With its branches high overhead like a set of upside down roots, it looks like it was plucked straight from a Dr. Seuss book. But something even weirder is happening inside.

After checking out this photo of a baobab in Madagascar, a Kinja-discussion kicked off with commenters musing on the hollow trunks of the trees and wondering 1) where their strange physiology came from and 2) just how you could possibly know how old they were:


I’ve always wondered how it is that baobab trees manage to generate sufficient energy to sustain their massive size despite the relatively tiny square area of their leaves.


They’re basically hollow inside. Much of the living cellular biomass of a tree lies only within the outer few layers of rings just under the bark - but I’m not even sure that Baobab trees even have rings due to the hollowness in the center - which means that people can’t really tell their age, at least not by ring counting.


Ask and you shall receive, Kinja.

Even without resorting to ring-counting, there’s a better even more reliable method of figuring out the age of an individual baobab. I’m talking about radiocarbon dating, which has placed several of the trees in the thousand-year plus range — and given us a clue about just where the hollowing out effect comes from.


A study published in PLOS One by a team of researchers led by Adrian Patrut out of Babeş-Bolyai University took multiple samples from all over several hollowed-out baobabs and found something surprising when they dated them: The age of the samples didn’t follow a normal pattern. Instead, they would see a pattern in aging, only to see it reverse a little later, which made the researchers say that when we see a baobab we’re not just seeing one tree; we’re actually seeing many:

The age values exhibit a continuous increase from the cavity walls up to a certain distance into the wood, after which they decrease toward the outer part. The only explanation for this anomaly, which represents a reproducible experimental finding, is that such inner cavities are in fact natural empty spaces between fused stems disposed in a closed ring-shaped structure. We named them false cavities.


Image: Baobabs in Madagascar / plizzba