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One of the great feelings of shame for many plant lovers is a latent hatred for certain plants which seem to have it out for humans. Of course, plants don’t think this way (if we can say they think at all, up for debate). To date, they are not out to get us. Nevertheless, contact with some of them comes with serious consequences.

Poison ivy, poison oak, and poison sumac all contain a resin called urushiol, and when it gets on human skin, we break out in an incredibly itchy, enduring rash. But, other plants can be problematic, too. And, some of them are highly regarded as useful, nutritious, and/or beautiful.

For example, plants like pistachios and mango also contain urushiol but don’t cause rashes for most. Cashew nuts have urushiol (and caustic acid) encasing them and do cause reactions.

But, not all troublesome plants have urushiol. There are lots of others, many that are common in the USA, that can cause skin irritations, regret, and the aforementioned latent hatred.

Source: Your Discovery Science/YouTube

1. Stinging Nettles (Urtica dioica)

Brush up against a leafy stinging nettle and there is little doubt about it. Those leaves are covered in tiny, hollow needles made of silica. Those needles are filled with histamine and serotonin which cause an unpleasant reaction when they get into the surface of our skin. This can cause intense stinging and a rash for up to a few days.

A famous home remedy for stinging nettle stings is to rub them with dock leaf, another common weed that often grows alongside the nettles.

Otherwise, stinging nettles have also gained the reputation of being extraordinarily nutritious. People are foraging them in the wild, and some gardeners are growing them on purpose.

2. Giant Hogweed (Heracleum mantegazzianum)

Like many problematic plants in the US, giant hogweed is a non-native, invasive plant that was introduced to our ecosystems and has wreaked havoc. It’s from the same family as carrot, parsley, and cilantro.

Aside from throwing nature out of whack, giant hogweed has sap inside it, and that sap contains furanocoumarins which can cause severe burns. This chemical prevents the skin from being able to properly protect itself from the sun. Exposure to UV light causes the reaction.

3. Wild Parsnip (Pastinaca sativa)

Along with poison hemlock and giant hogweed, wild parsnip is related to carrots. It’s also toxic if eaten, and it has the same compound in its sap as giant hogweed. In other words, touching wild parsnip and being exposed to the sun is a painful predicament.

Dealing with contact giant hogweed and wild parsnip is as simple as covering the skin until the sap can be washed away. Without the sun, the harsh reaction doesn’t happen.

4. Wood Nettle (Laportea canadensis)

Known as stinging nettle in some US states, wood nettle is in the same family as the other stinging nettle. It has the same basic setup as well. It’s a perennial herb with painfully memorable hairs on its leaves and stems. It’s also highly nutritious and common forage fodder.

5. Leadwort (Ceratostigma plumbaginoides)

Also called plumbago, leadwort is a mat-forming perennial plant that originated in China. It has pretty flowers and stays down to about 6-10 inches, spreading voraciously underground via rhizomes. It’s a common garden plant in the Southern United States.

Leadwort may be beautiful but touching it can cause redness and blistering, so wear gloves when handling it in the garden. Or, plant something similar like moss/creeping phlox.

6. Ragweed (Ambrosia spp.)

Much more notorious for allergies brought on by its pollen, ragweed can also cause skin irritation. Those who are allergic to the pollen in the air will have an allergic reaction to the pollen on their skin.

These plants are prominent in the tropical and subtropical areas of the Americas, particularly the Southwestern US. The species, however, has naturalized in many other areas, including a rapid invasion of mainland Europe.

Source: GardenClips/YouTube

7. Trumpet Vine (Campsis radicans)

Gorgeous native vines with amazing tubular red flowers that hummingbirds love, trumpet vines would seemingly be a gardener’s favorite. However, it has other names, too: “hellvine”, “devil’s shoestrings”, and “cow-itch vine”.

Trumpet vines are very good at spreading and dominating where planted. They have aerial stems that form across the ground and trip passersby. Worst of all, contact with trumpet vines results in poison ivy-like skin irritation.

So, what do we do with all this new information? Do we walk around nature and gardens in fear? Hopefully not. However, knowledge of these plants might allow us to stay a bit safer when encountering ferocious flora. Doesn’t that sound worthwhile?

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