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People love plants, for food, decoration, or just because taking care of a succulent
is a lot less responsibility than a puppy.
But many of the house plants that spruce up our surroundings are also poisonous.
Kids and pets are the usual victims in plant poisonings because they have a tendency to
explore the world with their mouths.
In fact, when the American Association of Poison Control Centers
compiles their annual poisoning report,
plants are typically in the top 10 causes of accidental poisoning in children.
So you can be aware of the dangers lurking in your house, here are 9 plants you might
have around your home that are actually pretty toxic if they end up inside you.
Dieffenbachia is a popular house and office plant because it
can survive without much sunlight or TLC.
But it can be bad news if you mess with it.
This plant has specialized cells that contain calcium oxalate crystals.
That’s the same chemical that makes up most kidney stones, which get stuck in the tube
that connects your kidneys to your bladder. Erh.
In Dieffenbachia, these crystals can come in a couple different shapes.
Druses have a star-like shape, while raphides are needle-like.
And researchers think that calcium oxalate crystals might have different functions in
different parts of the plant, from deterring hungry herbivores to adding structural support.
For instance, if cells in the tasty-looking leaves are damaged, like by chewing, they
can forcefully expel the raphides like microscopic darts.
These stabby crystals, and other plant proteins on them,
can severely irritate the delicate tissue in a mouth.
In humans, the swelling they cause can make it difficult to talk, hence Dieffenbachia’s
common name: dumb cane, dumb being an antiquated, insulting term for someone who can’t speak.
And if you’re unlucky enough to get a squirt of sap in your eye, those crystals can damage
your cornea, the clear protective covering on the front of your eyeball.
Like any other scratch, this can typically heal.
But it’s definitely not pleasant.
Now we usually grow daffodils and other members of the genus Narcissus from bulbs, they’re
a classic, cheery spring flower!
But they also contain a toxin called lycorine, which is a type of alkaloid.
Alkaloids are nitrogen-containing chemical compounds made by lots of living things,
including many plants.
They can be another way of deterring herbivores.
We humans use some alkaloids on purpose, like caffeine or nicotine, even though they can
have really extreme effects on our bodies.
And lycorine is no exception,
it causes vomiting, diarrhea, trembling, convulsions, and sometimes even paralysis.
Exactly what it does in our cells isn’t well understood.
Although there’s some evidence it might mess with protein synthesis.
People usually don’t eat daffodils on purpose,
but they can accidentally eat the bulbs thinking that they’re onions.
And that’s what happened to some school kids in Suffolk, England in 2009.
The kids were making soup using vegetables from a garden they had planted, when someone
accidentally added a daffodil bulb to the pot.
And a bunch of the kids got sick.
Thankfully they were all fine afterwards,
and hopefully they weren’t too put off from eating their veggies!
Oleander is a popular landscaping shrub in the warmer parts of the US because it’s
low maintenance, drought tolerant, and has some lovely flowers.
But there are some not-so-lovely parts too, like cardiac glycosides.
Cardiac glycosides are toxins produced by many different species of plants to,
you guessed it, deter herbivores.
Oleander specifically has chemicals called oleanderin and neriine.
And they interfere with the sodium-potassium pump in heart muscle cells.
The sodium-potassium pump does exactly what you’d think from its name: it pumps sodium
and potassium ions back and forth across the cell membrane.
This helps build up electric charges, and generates a cardiac action potential, which
helps coordinate signals that regulate heart muscle contractions.
So if you mess with the sodium-potassium pump, you mess with your heartbeat.
Specifically, cardiac glycosides inhibit the sodium-potassium pump and reduce the amount
of sodium ions it can pump out of the cell.
This slows down the heart rate, but increases the force of the heart muscle contractions.
Now, other cells in your body have sodium-potassium pumps too,
including nerve cells and the cells lining your gut.
So Oleander can mess with these too, leading to convulsions and gastrointestinal symptoms
like nausea, abdominal pain, and vomiting.
None of which sounds particularly fun.
Now, Rhododendrons are popular landscaping shrubs in the wetter parts of North America,
but this widespread genus of plants is also native to Asia.
And in the 1st Century BCE, they may have contributed to the
defeat of the Roman army in Turkey.
See, the pollen and nectar in rhododendron flowers contain grayanotoxins.
Like cardiac glycosides, grayanotoxins also interfere with cells’ ability to move ions
across the cell membrane.
But they mostly affect nerve cells, so they’re considered a neurotoxin.
They bind to sodium ion channels in the cell membrane, little pores that open and shut
to let sodium ions move into and out of the cell, which helps generate action potentials.
And when a grayanotoxin binds, sodium channels get stuck open, which causes all kinds of
mayhem in your brain, heart, and gastrointestinal tract, from hallucinations to vomiting.
Now, even though humans might not munch on rhododendron flowers for fun, bees visit these
flowers and make honey, which we have been known to eat.
This toxic honey is called Mad Honey, also the name of my elementary school rock band.
So the story goes: when the Roman army invaded what is now Turkey, the locals lined the route
with chunks of this Mad Honey honeycomb.
The Romans couldn’t resist the sweet treat, so they suffered from the toxic effects, and
the sick and delirious soldiers were easy to fight off.
So I guess the moral of the story is: Never eat mystery road honey!
A favorite flower for bridal bouquets and shady spots in the garden,
Lily of the Valley has a shady side too.
Which you might know if you’re a fan of Breaking Bad.
Lily of the Valley contains nearly 20 or more different cardiac glycosides, the same kind
of toxins found in Oleander.
One of the major ones is convallotoxin, which is one of the most active natural substances
affecting the heart that we know of.
Like all cardiac glycosides, it messes with the sodium-potassium pump and wreaks havoc
on your heartbeat, so it gets slow and irregular, or in extreme cases, undergoes cardiac arrest.
Lily of the valley also contains other toxins called saponins.
These aren’t very toxic by comparison, but if you eat a lot of them, they’ll give you
a pretty upset stomach.
Saponins are a lot like soap.
They’re surfactants, which means their molecules have a hydrophilic, or water-friendly, end
and a hydrophobic, or water-avoiding, end.
And you know what else is made up of carefully arranged hydrophilic and hydrophobic parts:
Your cell membranes.
So because they’re surfactants, saponins can punch holes in cell membranes.
And the cells lining your gastrointestinal tract do not appreciate this.
Most of the time when someone is poisoned by Lily of the Valley, it’s an accident.
Like a little kid that tried eating the plant’s inviting red berries, or one case study in
a medical journal of an elderly woman with dementia who loved the scent of some she was
given as a gift, and unfortunately ate them.
Hydrangeas’ fluffy flower poofs may look pretty innocent, but they pack a surprise,
a toxin called hydrangin.
Hydrangin is a cyanogenetic glycoside and when you eat it, some enzymes in your body
convert it to hydrogen cyanide, which you may have heard of before.
It’s real toxic stuff.
Cyanide binds to certain iron-containing molecules in your cells, and shuts down the cells’
ability to make that all-important fuel molecule: ATP.
Without ATP, your cells quickly starve and die, and so will you.
Thankfully your body can detoxify moderate amounts of cyanide, so you'd have to eat a
lot of hydrangeas to kill you.
And they taste pretty nasty, so a large helping would be hard to swallow.
But even eating small amounts of hydrangea will make your digestive tract cells unhappy
and cause diarrhea, vomiting, and stomach ache.
So if your kid or pet eats them, you should still get them checked out.
Sago palms are another landscaping plant used in the warmer parts of North America.
But they’re not closely related to tropical palm trees at all, they’re actually part
of an ancient group of plants called cycads.
Cycads were particularly abundant during the Jurassic Period, so you might remember them
from your dinosaur picture books.
But even if they look cool, they’re hiding a dangerous chemical called cycasin.
It’s not really the cycasin itself that’s the problem.
But when your body breaks it down, one molecule that gets produced
is methylazoxymethanol or MAM.
Now, MAM has a habit of damaging DNA, particularly in developing brain cells and liver cells.
Which sounds pretty bad.
It’s a DNA alkylating agent, which means it binds to DNA and can break strands or make
them stick to each other.
Which makes it hard for DNA to function or replicate properly, and that can kill affected
cells or cause them to become cancerous.
Still, you’d probably have to eat a lot of cycad to get enough MAM to cause problems.
But on certain islands in the South Pacific where people eat flour made from cycad seeds,
there are higher-than-normal rates of neurological diseases like Parkinson’s and ALS.
And some scientists think that cycads might be partially to blame.
One festive winter holiday tradition is decking the halls with boughs of holly, and with other
poisonous plants too.
But I’m not talking about poinsettias, they’re only mildly toxic.
You’d have to eat about 500 leaves to get sick,
and they taste terrible so it wouldn’t be easy.
Mistletoe, on the other hand, can be much worse.
Now, mistletoe species that are native to North America aren’t very toxic.
But mistletoes in the genus Viscum from Europe have a toxin called viscumin, which is similar
to ricin, which you may have heard of before.
Ricin is a strong poison made from the castor oil plant and was allegedly used in a tiny
pellet during the infamous umbrella assassination of the
Bulgarian dissident Georgi Markov during the Cold War.
And viscumin seems to be just as deadly.
An injected dose as small as 2.4 milligrams per kilogram of body weight
can apparently kill a mammal.
Both ricin and viscumin are ribosome-inactivating proteins, also known as RIPs, which is a kind
of morbidly appropriate initialism.
Ribosomes are the structures in your cells that assemble proteins, which do all kinds
of work to provide structure and regulate functions throughout your body.
When viscumin enters the cell it breaks up an important part of the ribosome, causing
irreversible damage and shutting it down.
And if your cells can’t make proteins, you’re in trouble.
Because everything starts breaking.
So, uh, even if there’s some smooching, don’t nibble on the mistletoe by mistake.
Potted cyclamen are popular gifts during the holidays, too.
They have delicate, colorful flowers, tend to bloom in the winter months, and can be
grown outside in mild climates.
But they also contain the toxin cyclamine, which is a type of triterpenoid saponin.
Like the saponins in Lily of the Valley, this toxin can mess with your cell membranes and
irritate your gastrointestinal tract, making you feel pretty lousy.
Thankfully, most of the cyclamine is tucked beneath the soil in the plant’s rhizome,
which is kind of like an underground stem.
And all that cyclamine gives the the rhizome a very bitter taste too, so even curious kids
or dogs are unlikely to eat enough of it to get seriously ill.
The leaves contain less cyclamine, and in traditional Greek cuisine some species were
used to make dolmas, little leaf wraps stuffed with rice and other fillings.
But, like, please don’t pretend you’re on Iron Chef
and make dolmas at home using random houseplants.
It’s not a good party idea.
In fact, “don’t eat the houseplants” is generally a good rule to live by!
You can rest easy for the most part, because it’d probably take a lot to get seriously
harmed by these plants, even with their toxic defenses.
But it’s always a good idea to contact Poison Control
and seek medical attention if it happens, just in case.
Thanks for learning with us here on SciShow!
If you’re still curious about poisons, and who isn’t, check out our list show about
6 so-called undetectable ones and how scientists can actually sleuth them out.
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