{♫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 not  killing it, you will never see it flower.

Yeah, I know what you’re thinking: “Not with  that attitude you won’t.” But seriously:   no one’s seen a pothos flower  naturally in almost sixty 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. That makes them super low-maintenance as house  plants, and really successful in the wild. So even though the plants  originated in the South Pacific,   they’re 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 ground cover 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 twenty meters tall. Those giant leaves let them get more   sunlight in the tree canopy and help  improve their chance of survival.

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

There’s 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’d 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 ought  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 a 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’ve skirted around the   topic of plant sex. But we’ve got 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 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 patreon.com/scishow -- and as always,   thanks for your support. {♫Outro♫}.