Giant hogweed is pretty gnarly. If your skin comes in contact with its sap, exposure to sunlight will give you severe burns and scarring. The photosensitivity can last for days even after the sap itself has been washed away.

I both love and loathe bamboo. It’s an incredibly useful and fast growing renewable resource.

It also will not fucking die when neighbors plant it in the ground vs a container. It will take over without constant pruning of offshoots. You have to put a barrier at minimum 6 inches deep to even attempt to contain it. Feeders will grow literally overnight and produce offshoots dozens of feet away. I don’t know of a single herbicide that will kill it.

I love you bamboo, but also you can die in a fire. Not that that would kill you anyway.

Turf grass. It’s the stupidest crop ever cultivated by humanity.

Lawns are an 17th century European fashion trend. We poison the soil with herbicides to defend grass. We poison the water with fertilizers to feed grass. Many US households through HOAs or zoning regulations are legally required to cultivate and martian grass. Grass doesn’t feed anyone, except the insects that die soon afterwards from all the poison.

https://en.wikipedia.org/wiki/Manchineel

This tree is the most toxic on the planet.

The fruit is deadly if eaten. Nicknamed the death apple

If you burn the tree the smoke will blind you

It’s pollen can cause horrible reactions of contact dermatitis to choking from the throat swelling up.

The sap has historically been used as a weapon poisoning arrows, and even the leaves have been used to poison water supplies.

That Cordyceps brain infection looked pretty bad in that Last of Us documentary

The destroying angel mushroom. It’s one of the most poisonous mushrooms in existence, symptoms of poisoning don’t appear until it’s too late for treatment, and it happens to look almost identical to several common edible mushrooms, because it just hates life.

I have heard so many bad things about Eucalyptus trees.

In fact, the latest bad thing i heard about them was in a koala copypasta submitted to the animal thread from last week, where it was insinuated that the abundance of eucalyptus trees is a large reason why Australia is barren/ecologically weird, due to their very low provision of calories. This obviously will not do. A mammal’s main love of trees is their ability to bear fruit.

Likewise, in California, the mass plantation of Eucalyptus trees led to very severe wildfires in the future (our present day). In part, this is just a debuff of any forest monoculture, but i have similarly heard that they’re actually more flammable than many other types of trees. [Edit: while source hunting, it looks like Eucalypti are actually known to BLOW THEMSELVES UP to remove competition. This makes them the suicide bombers of the natural world!!]

And what really bites the biscuit is that Eucalyptus trees STINK!! Their ultra minty sour fragrance seems so artifical to me - like worn down tyres, melted down and mixed with equal parts of antifreeze. I had the misfortune of trying eucalyptus flavoured chewing gum on a few occasions and it almost killed me. Psychologically. One of the worst things i’ve ever tasted and smelled. It’s like an alien plant trying far too hard to get us to like it.

I don’t know which fungi is the worst, but it’s probably a Cryptococcus sp…