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A moving plant that hides from predators when it feels their touch.
A little legume that goes to sleep when the sun goes down. A smart perennial that has learned
to be less shy the more it’s exposed. A role model for most of us. This is the Mimosa Pudica.
Hey I’m Tasha the Amazon and you’re watching Floralogic. Today we’re talking about our
favourite kind of plant. Plants that move. We’ve talked about carnivorous plants before.
They move to catch prey, but today’s species moves for an even more relatable reason.
It doesn’t like to be touched. At the mere hint of a caress
they fold their leaves inward, as if they were bracing for impact.
They’re called mimosa pudica, but no they’re not an ingredient in your favourite sunday
brunch beverage. The cocktail is named after an Australian yellow flower also called mimosa.
The mimosa we’re talking about is native to Central and South America, though it's been
introduced to every other continent except Antarctica. It’s name comes from greek
mimos, which means mimic, as in, they mimic the movement of animals. And pudica, which means shy.
And their name is well earned, these plants will only open up when they’re feeling pretty good.
They’ll close immediately if something touches them, or if it’s too hot,
cold, or if its stem is being shaken. But this is not just run-of-the-mill coyness,
this is actually a very effective self-defense technique against their two main worries in life:
dehydration and being eaten by a vegetarian. Most of their range provides enough rain to keep
them hydrated, but it’s also in the tropics, where the sun can evaporate the moisture
of unprotected plants. If the mimosa pudica senses it’s too hot out they close their
leaves to prevent their water from evaporating. And while other plants have thorns or chemicals
deter herbivores, these guys simply hide from them as much as they can. Turning their leaves
inward makes them look more like a twig and a lot less appetizing than other leaves.
And of course, a moving plant seems sketchy at best. Especially because one closing leaf can
start a chain reaction that makes several hundreds of leaves close simultaneously.
So, no thanks, better leave it alone and eat literally anything else.
If you see one outside, go ahead and tickle it and see it move. Just don’t overdo it.
It has a huge energetic cost, and can even affect their photosynthesis.
Which brings us to the question, how do they move?
Like other moving plants such as venus flytraps, they have an elaborate mechanism that changes
their cell size by adding or removing water. It's kinda like holding a sheet of paper
between two air balloons. If you deflate one slightly, the angle of the sheet of paper changes.
This mechanism is also activated at night when the plant goes to sleep. There’s no reason to be
open if there’s no sunlight to absorb. And, as we mentioned earlier, it’s a lot safer.
Not all mimosa pudicas live in the same environment and some are touched more often than
others, usually by harmless objects such as drops of water or larger animals walking by. So,
they have evolved to learn when to close. Sensitive plants need to maximize the
time they’re open so, in areas where they’re touch a lot, they learn to be less sensitive.
This also happens in areas with low light as they need to absorb all the light they can get.
This makes sense, but the tricky part is where they store the information
they learn. There are a couple of theories, one of which posits that the frequency a plant is touched
changes the way their genes are expressed. But, again, it hasn’t been proven.
If you’re a grad student and are looking for a research subject, consider helping us understand
how plants learn. Unfortunately for the mimosa pudica,
some animals are catching on with their ruse and are finding ways to eat them.
Silk-weaving predators are their worst enemy as they use their threads to immobilize their prey.
A classic spiderman move. Spider mites and mimosa worms, which
are really steel-grey moth larvae, are their main predators. Both are difficult to control and can
quickly kill a plant. So if you have them at home, make sure to keep an eye on them for parasites.
We're so excited to be partnering with Brilliant again for this video. Whether you're looking to go
into zoology computer science or you just enjoy learning new skills Brilliant is a great way to
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today just click the link in the description below or visit brilliant.org animal logic
So what should we talk about next? Please let us know in the comments and don’t forget
to subscribe for new episodes every week. Thanks for watching. Bye!
if you're a grad student looking for a subject looking for a thought if you're a grad student
looking for a research subject why not consider why consider helping us learn how consider helping
us understand how plants learn okay if you're a grad student are you are you in school are
you getting good grades are you studying are you doing your homework then use this
as your topic for your dissertation get a phd go to school learn get a degree put your degree
in a frame hang it on the wall let everyone see that you graduated and that you did a
dissertation on learning how to plants learn and then email me and let me know about it thank you