I’m genuinely asking out of curiosity, I’m not trying to shit on this sub, so don’t downvote plaese. There is r/shermanposting, and that’s a similar sub that is quite popular, but that’s for the confederates.
For Finland, it has to be the giant hogweed plant (Heracleum mantegazzianum). It’s a massive poisonous invasive plant originally from the Caucasus mountains in Western Asia, that was brought to here and many other European countries in the 1800s as an ornamental plant for gardens, or as an experimental hardy fodder plant for cattle, that has since escaped into the wild and can occasionally be found growing on riverbanks and roadsides. (Although thankfully here in Finland it’s *relatively* rare compared to for example the UK, Russia or Northern Norway.)
Even just the massive size of the plant alone makes it extremely scary and intimidating: it’s one of the largest flowers in the whole world, and the largest one in Europe. Even just the AVERAGE plants are easily 1,5 to 3 metres (5 to 10 feet) tall and tower over all the other vegetation that is not trees, and the very largest specimens can grow up to 4 metres (15 feet) tall. The flowerheads and the leaves can be more than 1 metre wide, and the stem of the plant can be as thick as an adult man’s wrist. The pics are not AI, I have seen them many times in person and they truly are that massive. But what makes it even more terrifying is the fact that it’s also highly toxic, and contains sap that can give you severe and painful burns and blisters just from touching the plant and brushing your skin against the hairs on its stem and leaves, and especially if you break or cut the plant without proper protective clothing.
The way it works is that the sap is basically a ”reverse sunscreen”, and it makes your skin extremely sensitive to sunlight. Touching the plant or the sap is not immediately painful in any way: it does not immediately sting you like a nettle or burn like an acid, it feels just like touchign any other leaf or a normal plant. But the sap contains a toxin that absorbs into your melanocyte cells that protect your skin against the sun’s harmful UV radiation, and causes them to die / stop functioning, which will then allow the sun to burn your skin extremely badly. There are actually dozens of similar ”phototoxic” plants all around the world that increase your skin’s sensitivity to sunlight, but the giant hogweed is BY FAR the most dangerous one with the strongest toxin. The patch of skin that has absorbed the giant hogweed sap can allow up to 150 TIMES more UV rays to penetrate it than a normal healthy skin, which will ABSOLUTELY cook you, and give you literal RADIATION BURNS.
The scariest part is that just like with a regular sunburn, you often don’t notice it in time while it’s happening, and the burns can start to develop as late as 24 hours after the exposure to the plant’s sap and the sun. So in a worst case scenario, if you absorb giant hogweed sap on your skin without noticing or knowing what it is, and then after it spend like 4 hours outside on a hot and synny high UV day, you can end up with absolutely HORRIFIC burns. Like literal 3rd degree burns where your entire skin peels off, that are excruciatingly painful and require skin grafts and days spent in a hospital. Here are some examples of how bad they can be (graphic warning!):
https://www.thesun.co.uk/health/22634064/holiday-ruined-plant-worse-japanese-knotweed/
https://people.com/human-interest/alex-childress-burn-hogweed-virginia/
To be fair, here in Finland the plant isn’t usually AS dangerous as it can be in the more southern / central parts of Europe, as the UV index is often relatively low here even in the summer. But still, even here I have heard that the blisters and skin irritation caused by accidentally touching this plant can be very painful and severe. (Remember that it causes your skin to have 150 times more UV exposure than normally, so even on a cloudy day it can burn quite badly.) And on top of all this, if you are somehow unlucky enough to get the sap in your eyes, it can cause permanent blindness. The toxicity combined with the fact that the plant is so tall and enormous (even in its average size easily tall enough that it can brush against your FACE, if you are for example pushing your way through riverbank bushes on a fishing trip and don’t notice it) makes it absolute nightmare fuel in my opinion.
Because the plant is so dangerous, it’s nowadays banned in the entire EU and it’s illegal to buy it, sell it or grow it in your garden. The naturalized populations growing in the wild are also actively being eradicated by local environmental agencies whenever they are found. As a nature and outdoors enthusiast, I personally have a bit of a morbid fascination with these plants. They truly are the kind of next-level nightmare stuff you would only expect to find in Australia, not in Europe or Finland. I have actually even ”professionally” removed them from nature during a summer landscaping job. When mowing the plants down, you need to wear a full hazmat suit like you were some kind of ebola doctor, to keep the sap away from your skin. The seeds need to be burned to keep the plant from spreading further.