Ask just about any person who’s gone through puberty: hormonal changes can have some interesting effects on human growth.
They can have some interesting effects on plant growth, too. Like humans, plants have hormones running through their systems. True, plant hormones aren’t the same as the ones found in humans and other animals, and they act in completely different ways than animal hormones do. When it comes to trees, though, in some cases plant hormones have an effect similar to the one that testosterone and everything else in the human chemical cocktail had on most of the boys in my junior high class: they cause them to grow long, spindly limbs.
Like other plants, trees produce hormones in different parts of their bodies, such as the tips of their branches and deep down in their roots. When those parts get damaged, the distribution of hormones throughout the tree changes. Suddenly, the redistributed hormones cause thin, quick-growing branches to develop from previously dormant buds, called epicormic buds, along the branches and trunk.
The shoots that arise from these slumbering buds are known commonly as water sprouts. When water sprouts grow along other branches, they grow vertically, shooting straight up toward the sky like hands of the newly risen dead bursting forth from the grave in a zombie flick. When these
monsters shoots emerge from the trunk, the concept of vertical growth sometimes gets a little tentacle-y instead, as you can see in the photo that inspired this post’s illustration.
Aside from their occasional resemblance to Lovecraftian appendages, water sprouts are discouraged for other reasons. As some have pointed out, water sprouts block air and light from moving among a tree’s branches, inhibit fruit growth, break easily, and divert energy from stronger branches.
Water sprouts also grow back easily, as pruning a water sprout creates a fresh wound that the tree ends up attempting to compensate for with new limbs and more leaves for carrying out photosynthesis. It’s not quite the same as the whole cut off a limb, two more will take its place dynamic that fans of Marvel Comics will appreciate, but it does make plant growth one more example of regeneration in nature, alongside some impressive mentions from the animal kingdom:
Of course, the hydra, a relative of jellyfish, with tentacles that would make a tree with water sprouts feel envy if trees could feel such emotion. The hydra constantly generates new cells, meaning that if a hydra is cut in half, the cells from the creature’s main body column will differentiate. One half will grow a new head; the other will grow a new foot. And the cells retain a “memory” of which side of the body is up and which is down, even after being spun in a blender, which is better than I can do after a roller coaster ride.
Octopuses, while I have water sprouts and tentacles on my mind (though an octopus’s appendages are referred to as arms, not tentacles). Male octopuses use one of their eight arms, called a hectocotylus, specifically to give packets of sperm to their female mates. It’s a gift that keeps on giving: males of such species as Abdopus aculeatus lose that arm during copulation and regrow a new one later.
Salamanders, such as the axolotl. Thanks to the activity of certain genes, along with a little bit of electrical stimulation that’s believed to be carried along nerves, salamanders can regenerate a lot of their organs, including parts of their brains and spinal cords.
Can’t forget about flatworms, a.k.a. planaria. As researcher Thomas Hunt Morgan discovered in the 1890s, cut one flatworm up into 279 pieces, and 279 more will come back to take its place. It’s fascinating any time the action of genes ultimately triumphs over the action of a knife.
Human beings exhibit a lot of different kinds of talent that other forms of life on this planet don’t. You’ll never hear about an octopus preparing dessert or a tree repairing a car’s transmission. When it comes to composing operas, I feel pretty confident in declaring that no other organism here has us beat.
When it comes to regenerating parts of our bodies that get damaged, however, compared to other creatures, we might seem rather unimpressive. Some parts of our bodies can regrow over time; the liver is a notable example. But brains, or even our fingers? We’re notably capable when it comes to reworking the world around us, notably less capable when it comes to repairing ourselves.
At least, we are right now.
Some researchers believe that the genes like the ones that stimulate regeneration in flatworms and salamanders could be activated in human beings, too. If so, human development could go well beyond the awkward growth spurts we experience around age 13. We could begin treating severe injuries in ways previously unimaginable.
Hail Hydra indeed.