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Uploaded:2021-04-12
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The pothos plant grows really well in a lot of places, so you’d think they’d be easy to coax blossoms out of, but even the greenest thumbs haven’t seen this plant bloom naturally in over 60 years! Why are the pothos petals so shy?

Hosted by: Hank Green

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Sources:
http://www.jcreview.com/fulltext/197-1572431971.pdf
https://www.nature.com/articles/srep28598
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-185X.1959.tb01301.x
https://link.springer.com/article/10.1007%2Fs40415-016-0331-6
https://www.sciencedirect.com/science/article/pii/S0254629916337760
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0192956#pone.0192956.ref014
https://www.researchgate.net/publication/272659426_Molecular_and_physiological_role_of_Epipremnum_aureum
https://edis.ifas.ufl.edu/fp194
https://www.jstor.org/stable/20789454?seq=1
[ intro ]

Pretty much every person thinking they might get a plant has Googled "plants I can't kill." And those search results probably told you to get a Pothos plant.

But no matter how great you are at killing it, you will never see it flower. And I know what you're thinking: "not with that attitude you won't!" But seriously, no one has seen a Pothos flower naturally in almost 60 years.

Pothos vines can grow a few ways: trailing down from planters, horizontally as ground cover or climbing up trees. They absolutely love shade. Plus, the aerial roots that allow them to climb trees also let them pull water from the air.

This makes them super low-maintenance as houseplants, and really successful in the wild. So even though the plants originated in the south pacific, they are now found all over the world as an invasive species. What's funny is how they got there.

Pothos is an angiosperm, a plant that reproduces by using flowers to produce seeds. So you would think that Pothos would do that. But for the most part, it doesn't.

Many plants just aren't mature enough to flower. The cute little houseplants and the shade-loving horizontal groundcover are just tiny li'l babies. Only vertical, tree-climbing Pothos plants are considered fully mature by botanists.

And these adult plants are way bigger than the ones in your apartment. Their leaves can be up to a meter long, and the whole plant can be 20 meters tall. Those giant leaves let them get more sunlight in the tree canopy and help them improve their chance of survival.

So those enormous mature plants are the ones that flower, right? No! Not for the most part.

There is only one recorded instance of a Pothos plant flowering naturally, ever. Even in the wild, Pothos spread vegetatively through cuttings or broken-off leaves. They don't create baby Pothos plants by flowering.

In fact, it seems to be nearly impossible for them to do so. It turns out that Pothos plants lack the genes to make growth hormones, called Gibberellins. Gibberellins are responsible for a bunch of different kinds of plant growth, including flowering.

They're basically signals that tell the plant what to do and when, like "look alive, it's flower time!" So without Gibberellins, Pothos plants never get the signal to start flowering, and they almost never flower naturally. In lab studies, researchers have persuaded Pothos plants to flower by artificially dosing them with gibberellins, which might actually bypass other important checkpoints telling the plants to hold off. But they're still figuring out the ways that Gibberellins interact with the plant's age, the amount of light, and the time of year to result in flowering.

Until they understand that, it's hard to say why these plants have genetically lost their ability to flower. Because you would think that flowering would be beneficial. It's why flowering exists.

Reproducing by flowering lets a plant mix its genes with other plants. That increases genetic variation in the population, which aught to help the plant survive in new habitats, resist disease, other good stuff like that. But many plants that can reproduce through either flowering or vegetation tend toward vegetation when they live in really dense populations.

That's because if one individual plant is doing great in their particular environment, they don't fix what ain't broke. No reason to make vulnerable little seedlings if they already found a genetic formula that works. So Pothos may not need to flower precisely because they grow so well.

But whatever the reason, they don't, so unless you get your hands on some Gibberellin, that Pothos plant on your bookshelf just isn't going to flower, no matter how green your thumb is. For this whole episode, we kind of skirted around the topic of plant sex. But we have a podcast where nothing is off-limits.

It's called after hours, and it's available as a perk on our Patreon. It covers all the really weird stuff that we can't talk about on YouTube. It's one of my favorite things that we do.

If you're interested, you can get started at https://www.patreon.com/scishow . And as always, thank you for your support.

[ outro ]