Does poison ivy play any useful role in the ecosystem?

Although we have a pond, I rarely get a mosquito bite thanks to our barn swallows and bats.

Should also be mentioned mosquito larvae feed a lot of fish.

Hate the diseases they carry though.

You would think we’d have horrible skeeters here in the sub-tropic(?) South Arkansas. But we don’t. Lots of birds, frogs, fish.

The pond is not nearly stagnant water, being deep and spring fed.
I don’t like standing water.
I keep pet dishes for water changed. Long since got rid of a bird bath since they never bothered to bath. Stinky birdies.

Skeeters don’t like us. I guess.
Now, hop down the road a piece, to the lake and you’ll get chewed up.

Regarding hemlock, there’s tons of warnings about how poisonous it is when ingested, but everyone seems to suggest it’s also dangerous to touch, treating it like poison ivy, etc. But is it? Nobody seems to have a good explanation of what might happen, if anything.

Virginia creeper anyone? We have some growing around our barn. I think it’s pretty. My gf has been trying (unsuccessfully) to eradicate it. She is unusually sensitive to it and gets a rash even though she wears long sleeves, gloves, etc. Has zero effect on me.

Virginia Creeper isn’t poisonous, but it has oxalate crystals in the sap that can cause irritation in people with sensitive skin. That would apply to Dumb Cane, Caladium, Elephant Ear, and Philodendron as well, though different leaf structures may expose more or less of the oxalate. The thing is, Poison Ivy and Virginia Creeper like the same habitat, and their leaves look very similar. The only immediately noticeable difference is that Virginia Creeper has five leaflets instead of Poison Ivy’s three. But young Virginia Creeper leaves often have only three leaflets, making it look just like Poison Ivy. So it’s entirely possible to have some Poison Ivy mixed in without knowing it, and you can get a rash just from touching the vines/stems, even woody or dormant/dead ones.

Yep. Virginia creeper is not noxious, but any plant can cause irritation. (I know people who get rashes after contacting lawn grass.) And, as I described earlier, Virginia creeper will outcompete poison ivy, especially with some human help.

I’ve been pulling up staghorn sumac, and dogbane both have sticky saps that are irritating but not as bad as PI. I’ve never encountered poison oak or poison sumac to my knowledge.

Interesting bit about dogbane (Indian Hemp) and staghorn sumac both plants among other uses were smoked using the dried leaves by native Americans,as an aphrodisiac or to attract wildlife.

Can confirm. In my youth I seemed to have no reaction to poison oak, which served me well as a surveyor for a civil engineer until he directed me to cut a tunnel along a sightline through a thicket of the stuff. Too much, my immunity was overwhelmed and I’m now highly sensitive.

My understanding is that the urushiol in poison ivy creates an allergic reaction and/or overreactive immune response in people. Nobody reacts to urushiol the first time they are exposed to it, but the body’s helper T-cells are typically primed to react if they encounter it again.

Some people never get an allergic reaction to urushiol, but most people get a stronger and stronger reaction every time they are exposed to it. So someone who doesn’t react may indeed be one of the lucky few who aren’t allergic, or they could be simply using up their free passes.

On a related note, I have been unable to recognize poison ivy most of my life. I also had no idea what Virginia creeper looked like, or Oriental bittersweet, or all kinds of other plants. Recently, after blundering into poison ivy on my property yet again, and being unsure what was poison ivy and what wasn’t, I searched for and found an app for my iPhone that identifies plants by taking a photo of them. It has been life-changing. The app costs money, but is worth every penny so far as I’m concerned. Plus, I’ve been able to train myself to finally recognize poison ivy even without the app.

Goats love that too.

Is there ANY living organism that doesn’t play a useful role in the ecosystem?

Human-introduced invasive plants, I’ll say they are the opposite of useful. But since native plants have been part of that ecosystem since, well, it was that ecosystem; by definition they have a place in it.

Here’s a general way to remember what poison ivy and oak look like. Both the words ‘ivy’ and ‘oak’ have three letters and the plants have leaves in groups of 3. Poison ivy leaves have pointy ends like the letter ‘I’ in ivy. Poison oak leaves are rounded like the letter ‘O’ in oak. But you don’t really have to differentiate between poison ivy and oak. They both have similar effects. If you want to be really safe, just remember ‘Leaves of three, let it be’. Unfortunately, not all irritating plants have leaves in groups of 3, and not all plants with leaves in groups of 3 are irritating, so you can’t use that as a universal guide.

You mean other than my ex?

Kudzu

Kudzu is a plant out of place. In its native environment it doesn’t swallow whole buildings and slow moving animals.

I don’t know. Never been to where it hails from.

That stuff is quite the opportunist.

The tomatoes are mostly harvested at the big farming concerns so the migrant farm workers have down time til time for watermelons. They’ll be out pulling vines. They make a few pennies per pound from who-knows-who for the vines.
That’s the only folks I see getting any use from it.

Homo sapiens typically do not. House cats are an ecological terror. Certain pathogens have wiped out whole species. The fungus Batrachochytrium dendrobatidis aka bd, has caused the decline or extinction of over 200 amphibian species, probably over 600.

Kudzu is a complex species long in cultivation in China and Japan. It was originally imported to North America as a forage crop. It’s a legume like alfalfa, it’s very nutritious and palatable to livestock, but unlike alfalfa it is difficult to bale and to store, so it’s mainly just grazed, mostly by goats. Of course, in British-colonized countries goat is a deprecated meat, so there’s not much real use for it and little to control it.