A destroyer of forests and possibly the largest organism to ever live, even bigger than the
Giant Sequoias. Armillaria challenges of our ideas of what it means to be an individual.
What makes this parasite such a successful killer that can live for thousands of years?
This is the Armillaria fungus, the humongous fungus.
Hi, I’m Tasha the Amazon and you’re watching Floralogic.
Today we’re talking about the largest living organism on earth, and how to catch and eat it.
No, we’re not telling you to become a whaler and hunt blue whales, or to wear your finest
flannel and become a giant sequoia lumberjack. The largest living organism in the world is
actually a delicious mushroom the size of 1800 contiguous football fields.
This humongous fungus’ real name is Armillaria Ostoyae.
Members of its genus are commonly known as honey mushrooms due to their delicious yellowy caps.
Don’t get too infatuated with these cuties though, this fungus is a
parasitic tree killer that can wipe out forests. In 1998, Malheur Forest in Oregon was a botanical
crime scene. 112 trees had mysteriously died. Investigators scoured the forest,
collecting evidence from their roots and the soil. After bringing them back to the lab
they realized the murderer was armillaria ostoyae, and that trees as far as 4km away
were being parasitized by the same individual. Further research showed that the fungus was 9.1
kilometers squared, four times bigger than the country of Monaco. It is also about 35,000 tons,
which is about 250 blue whales, and it was around 9600 years old.
Once they get to a tree, the fungus spreads root-like rhizomorphs
under the bark and around the roots, absorbing all the nutrients from them. Eventually the tree dies.
This particular individual has managed to survive this long because the pacific northwest has a huge
density of trees, and thus a steady source of food. The humongous fungus specializes in
douglas-fir, pine trees, and other softwoods. Luckily their growth is incredibly slow,
only a few meters per year, and can be blocked by planting more resistant trees such as hardwoods.
But when unimpeded, it thrives. The fungus has adapted to consume both live
and dead plant matter. So, unlike other parasites, it doesn’t have a need to keep its hosts alive.
One of the weird things about this mushroom is that it doesn’t grow like plants and animals.
Instead it can create clones and then fuse with them into a single organism. Weird.
The system works like this. Armillaria reproduces sexually.
The delicious yellow mushroom caps you see above ground releases the spores into the air. There are
two types of spores, which are not technically male and female, but work in a similar way.
If the two types of spores get in contact with each other, they form into a fungus.
If the two spores were released by the same fungus, the new individual will have the same
genetic makeup and will be technically a clone. It’ll grow independently, spreading its mycelia,
which are the equivalent of roots in fungus. Most of the fungus mass throughout its life w ill
be mycelia. You might even have seen some at home in food that’s getting a little older.
And if this new individual gets in contact with its parent or another clone, it will fuse with it,
becoming just one organism again. They continue doing this for thousands of years and eventually
you get a humongous fungus. You might be thinking, is a
network of fungi really just a single organism? The answer is, of course, technically yes.
By definition, an organism is a group of genetically identical cells that can coordinate
to do something together. The cells of the tip of the nose of a giraffe are genetically identical
to those at the tip of its tail. And so are the cells at the edges of the humongous fungus. The
difference is that in the fungus case they started in what looked like a completely separate body.
If you’re far from Oregon, you can still see these giant fungi all over the world.
If you can, and it’s safe, go to your local forest in the fall and look for honey mushrooms.
You can tell them apart by the gills under their cap, the ring on their stalk, and the white spores
it leaves if you put them on a hard surface. They might not be the exact same species,
but they’ll likely be part of a large network of genetically identical mushrooms.
And if you happen to see Armilliaria Mellea at night, you might even run into a lightshow,
as this species has bioluminescent mycelia. Now,
we can’t tell you to eat anything you see in the wild. But if you ever see them at the store,
they’re delicious in stir fries and pasta. Let us know your favourite recipes.
So what should we talk about next? Please let me know in the comments and don’t forget to subscribe
for new episodes every week. Thanks for watching. See ya!