There are other plants with urishiol that can be worth knowing about as well but that is a local thing. Poison oaks (Toxicodendron pubescens, Toxicodendron diversilobum) are pretty common in the US.
My mom had a brush with hogweed that gave her surprisingly bad sunburns many years ago. I keep away from most of the angelicas to avoid a similar reaction.
I recently learned about this tree in Florida where all parts of the tree can cause contact dermatitis, though not with urushiol. Even standing below it in the rain can cause rashes.
https://en.wikipedia.org/wiki/Manchineel
Manicheel sounds horrible. It's in spurge family, known for skin irritation in more northern species. This is like the spurge from hell. Native and endangered in Florida.
Hogweed's super scary also. It's all over North America apparently. It contains furanocoumarin, a phytotoxin, and touching the plant sensitizes skin to sunlight. It can cause severe burns, necrosis requiring amputation, and permanent blindness.
A fact I just learned from looking it up: Species similar to giant hogweed, Heracleum mantegazzianum, are ALSO phototoxic. Did not know that! I thought if you could ID it as cow-parsnip or whatever, it was "safe." NOT. These include - Common hogweed, H. sphondylium -- Cow parsnip, H. maximum -- Wild parsnip, Pastinaca sativa -- Wild lettuces, Lactuca sp. -- Angelica, Angelica atropurpurea -- Queen Anne's lace, Daucus carota.
Other hogweed lookalikes in Apiaceae include the hemlocks, similar appearance but feathery leaves, which go WAY beyond phytotoxicity (all parts of the plant are fatally poisonous to humans).
Fun times. Steer clear! The cool thing about botany is, there's always something more to learn.
My score was 45/55, with a couple fat-fingered clicks but still I was fooled sometimes. Even if you're not the woodsy type, it can be found alongside paths in city parks and etc, so good to know how to recognize.
It is everywhere. I once did a photo essay of a local abandoned insane asylum. Some of the buildings are covered with poison ivy, like English ivy (often, both).
I know a couple of landscapers that ended up in the hospital, because a few strands of poison ivy ended up in some brush they were burning (which they shouldn't have been, anyway).
If I understand correctly the problematic thing is urushiol which can withstand high temperatures. So all you do is fling this extremely horrible stuff into your lungs.
Basically you need an incinerator to actually burn it - otherwise you’re just spreading it airborne.
I know someone who had an older relative who did this back in the 1950s — they did a bunch of yard work, and figured they’d burn the waste. It turned out that this was a popular laundry day in the neighborhood when most houses had things drying on the line. After the third or fourth neighbor mentioned the mysterious rash, they realized what they’d done but wisely kept the secret for years.
I recently tried a soup in Korea (옻닭 or oht-tak) made from Toxicodendron vernicifluum before knowing what it was. The people I was with were very insistent that I take a pill to neutralize the allergen (urushiol, found also in poison ivy, is technically an allergen rather than a toxin) before I ate it.
Not everyone reacts to it, but when they do, it's pretty bad. The others I ate with have no reaction to it at all.
> Not everyone reacts to it, but when they do, it's pretty bad.
I have had it a couple times, with leaves brushing my skin. Huge, weeping sores all over my arms, chest, stomach (and worse), like leprosy (I imagine, anyways, never seen a photo of a leper). I can't even imagine eating it.
Similarly, I saw an episode of "Flavorful Origins" on Netflix, "Lacquer Seed Oil", which collected the fruits of the Lacquer tree (basically a poison ivy tree). They ground up the fruits and cooked the pressed oil to neutralize the urushiol (how did they not die from inhaling it??), and then they made a lovely tea with the oil with local bee larvae.
Honestly, it was nothing remarkable. It's used in eastern medicine to treat various ailments, but the flavor itself didn't have any sort of lasting impression.
The best thing to come of it is a story of having "poison ivy chicken."
That's the first I've paid kudzu any attention, but looks like its "vine"/stem (not a botanist) is quite distinct from poison ivy, so that should make it decently easy.
It's good to recognize the vines that run up tree trunks as well. Easiest when they have leaves, but they don't always have leaves especially in shady areas. The bigger vines tend to have a hairy or bushy look, lots of little root-hair like bits, that seem to help it cling to the tree bark, and these seem to have a reddish hue about them.
I forgot all about poison ivy's appearance as a (dried out) vine, and I proceeded to cut and rip huge chunks of it off a spruce tree in my yard.
The first indication I made a huge mistake was a relentless cough all that evening from the dust it generated as it broke off the tree. For the next month, I had horrible patches on my forearms and random other spots on my trunk where either it grazed me or I touched with my contaminated gloved hand. Luckily, I had some beta methadone lying around that helped the worst of the itching.
Even the dermatologist, when I saw him about 2 weeks post exposure, was horrified.
I had a terrible experience this summer from a dried poison ivy vine on a fallen tree. I can still see the marks on my skin where I had the awful rash. Really took me by surprise.
If you look up the tree you can often see some poison Ivy leaves. The large vines are what you want to get rid of to stop it spreading. As far as I can tell, birds eat the berries and poop it out while perching in other tree, which is three main way that the plant spreads
I want this quiz, but for poison oak. There's so much blackberry and other stuff in the bay area that looks awfully similar. I'd rather learn how to reliably identify it than be afraid of ... everything.
Blackberry has thorns and serrated leaves so you can distinguish it fairly easily regardless of season. When there are leaves on the plants there aren't really many plants that are easy to confuse with poison oak around here. Just look for leaves that come in sets of 3 leaflets with rounded/smooth lobes.
I agree, I find it easy to identify in any season. We have few plants that resemble it or its growth habits in anything but a superficial way, plus poison oak is much less variable in leaf size and shape than poison ivy.
The buds and stem tips are especially good giveaways, but I didn't really realize it until I lived somewhere with multiple species of sumac.
It's great you don't have trouble. I don't have that confidence yet. I've been using a plant id app to check when I see it and I've gotten it wrong both ways.
> The leaves may be notched, round, or oak-like depending on what other foliage is around the poison oak plants. They may be shiny—or not. They may have a red tinge—or not. This is where the challenge of identifying these plants comes into play.
...
> The actual shape of poison oak's leaves change based on the environment it is growing in, with the lobes able to vary on the same plant.
I'd also love a poison oak visual quiz! Something I learned recently is that poison ivy isn't native to California—it's three variants either grow in Asia, the eastern US, or "not California." [1]
I'm a native Californian, have never knowingly seen poison ivy, only poison oak, and I still got 48/55. So it's still a helpful quiz IMO. Oak does tend to take slightly different form factors depending on its environment e.g. it can climb if it's around trees or stand independently if not; not sure if ivy does that.
I got 52/55 and I went quickly. Do I spend too much time outside?
People often ask me how to identify poison ivy. And I try to teach them. I think I do a decent job. It’s not as simple as one or two markers. But at some point you just develop an instinct
Same score, and most of these plants aren't native here (W Oregon) and I wasn't familiar (in particular jack-in-the-pulpit got me 2/3 times, and then sarsaparilla appeared once).
I get asked to teach people plant ID sometimes, and people often seem mystified by it, until I explain the concept of "search image". It seems to give them a new way to approach it and seems helpful in most cases. Probably related to what you mean by "developing an instinct".
The nice thing about whoops you're wrong this is a Raspberry is that you're never going to make that mistake the one time you want to touch the Raspberry plant.
More generally speaking, plant identification is something I'm terrible at and really want to get better at.
I (think) I got poison ivy on my leg this past summer for the first time in my life while golfing. I must've either gotten a ton of concentrated urushiol in one spot or be very allergic because the blistering was extreme. Nasty stuff and left a scar.
This is fun, but sometimes it's only clear through context clues. Poison ivy is VERY adaptable. It can look like ground cover or like a bush or like a little tree.
It would be great if they had an alternate view for the ones that people get wrong.
I got 50/55. I think one of my big problems was not being able to tell textures from the photo, or not getting a clear view of the stems and runners.
Good thing I'm not one of those people. (Yet. Repeated exposure can apparently eventually make me one of those people. But I've made it a half century so far despite living on the east coast, being semi-frequently exposed while hiking, running, yard-work, etc, and never really worried about it.)
Haha I had to go and confirm, you're right (it's 35/55 for those who don't want to click a button 55 times). And here I was feeling pretty good about my 42/55...
I was you until a couple of years ago. Could have rolled naked in the stuff. Then it got me. And Lord, it was horrible. Weeks of agony. I’m super careful with it now.
> Yet. Repeated exposure can apparently eventually make me one of those people.
This is a good reminder for people. Most people only start getting it after a few exposures. I know of at least one early exposure that should have been really bad that nothing came of, but I've had it a few times since. I'm pretty careful these days though: 54/55.
...Now I know I'm going to get wrecked this summer.
This video about how to wash off poison ivy changed my life. The key is that urushiol acts a lot like invisible motor oil in terms of how it sticks to your skin https://www.youtube.com/watch?v=4oyoDRHpQK0
The answer in the video is Dawn liquid dishwashing soap and strong scrubbing with a cloth.
I want a product that can show me where the oil is on my skin. I'm strongly affected by poison ivy. I sweat a lot, so I'm constantly touching my face. I've had bad rashes on my nose, eyebrows, and ears, amongst other places.
I use a soapy cloth every time I think I've been in contact and I still miss places.
My grandparents always swear by using "brown soap" if you think you've been exposed to poison ivy. aka Fels-Naptha. It's a pretty strong soap, but I don't think it contains naphtha anymore.
Even worse, it is almost impossible to find these days. The brand was acquired and the company that bought it is still ramping up production and distribution. Source: I emailed the company.
Actually just bought some Zote (also now owned by the same company), just yesterday, to test it out... but from what I hear, I don't think it is as good.
The video says that the most important thing to do is wash every possible surface with friction (wet wash cloth or luffa) and to be exceedingly thorough in it. Additives didn't seem as important, though it probably is good to use some kind of soap.
Strong detergents like Dawn can trigger eczema -- they destroy the tight junctions between skin cells and let foreign materials through your skin that your immune system reacts to. I've had great luck switching to milder traditional soap made from lye and fat, which isn't strong enough chemically to do this.
Discovering this site was a godsend for my son, who had severe eczema as a baby: https://www.solveeczema.org I would also get itchy skin hands after washing dishes, now, my skin feels great.
I've not tried using traditional soap for washing off poison ivy, though it does work for other kinds of grease, so I would expect it's ok as long as you scrub well enough with a cloth or something.
That would be ideal, but in its absence I have had success (mostly) using a barrier cream to keep the oils from reaching my skin in the first place. I buy it from a marine equipment store, where it is sold for people working with glass fiber and resins.
A friend sent me that video a couple years ago, after seeing how much time I spend in the woods. Changed my life too!
He's right that scrubbing hard with a cloth is the most important part. For spot exposures mid-hike, a hard scrub with plain water in a stream or river, even without soap, has worked for me. A stone or a piece of bark can work as your scrubber. Better than your hand or your shirt. I swear that guy's saved me weeks of agony. Thanks for sharing.
I used to end up at the doctor every time I got poison Ivy, becuase it was so out of hand. That is until I took the time to understand urishol, and invest in "extreme green power hand scrub" which used to be called mean green soap, but they got in a trademark dispute with a bigger company.
extreme green power hand scrub is the same ingredients as zanfel, which is like $40 for a tiny tube. I keep tub of it in my shower and any time I see it starting, or think I may have come in contact I scrub the crap out of it, and it goes away in a few days. I haven't had a major breakout in well over a decade, and I reccommend it to everyone whenever the topic of poison ivy oak sumac or cashews comes up.
I have tons of it in my yard, and I'm genetically incapable of recognizing it by sight. I've gotten it 3 or 4 times in the past 10 years, and it's really annoying. I have some other type of vine, it's maybe kudzu but I'm not sure, that has completely enveloped trees, fences, climbing up my house. It's certainly intertwining with poison ivy and all the other plants and could very well pick up the oil from it.
There's an old movie called The Day of The Triffids, about walking/ambulatory plants, and you could shoot a remake of that in my yard and probably not need special effects. Kudzu can grow so fast you can almost see it in real time.
For us, we moved into a house that has about an acre of forest land. We’ve been trying to clear it out so the kids don’t come in contact with it while playing back there.
This video was a game changer for sure. It's amazing to see it racked up 8M views over the years.
There was a scientist at UC Santa Cruz who patented a chemical that could be used to detect urushiol under a blacklight. I contacted them years ago to see if they were going to turn it into a commercial product, but AFAIK, it hasn't made it to market yet.
The idea is intriguing... a special light or cream to make urushiol visible on the skin to aid in scrubbing it off. Now that would be truly life changing!
54/55. Grew up in Ohio spending every day off trail in the woods. Misidentified one because the site gets cropped off on mobile and I got over confident and didn't scroll to see the whole photo.
52/55...had a couple of false positives, because I'm paranoid. I'm pretty sensitive to it, and it's all around where I live. As careful as I am, though, I still manage to get it once or twice a year.
False positive won't hurt me, false negative will. A little exposure is bad enough on me, but even a moderate amount and I go to the doctor before it turns into a dangerous situation.
Two summers ago it took me 3 months to recover from a poison ivy "attack". I had washed it off with Dawn detergent but obviously didn't do a good enough job. Once I realized it had got me, I used large bandages to keep myself from scratching it in my sleep. I still have scars around my ankles & calves from the blisters. Now that I know I'm super sensitive to Urishiol I'm not taking any chances - I ALWAYS wear long pants and sleeves when in the woods.
As a kid I got really severe all-over-body poison ivy. Two decades later, I can’t eat mango despite how much I’d like to. Even if someone else peals it and cuts it up for me, I end up with an itchy rash around my mouth and tongue. Be careful.
The mistake I made was allowing my ivy'd clothes to touch seat cushions and especially my bed sheets. I was touching fabrics that had the oils on it over and over and even sleeping in it. Wash everything that was involved in the incident!
46/55, half of my wrong answers were false positives (those are better! I’d rather not take the chance). I’m pretty happy with that after 20 years living without the dreadful stuff.
For folks who don’t already know:
- three leaves in a cluster is a good warning sign
- redness of the stem where the cluster meets is a telltale
- the leaves generally have a point at the end, and may develop points along their sides
- dry looking roots going vertical is a bad touch, just… don’t bother unless you’re escaping some other danger
- If you’re like some of my family and get it from the wind, none of these guidelines have any value, I’m sorry!
200 comments
[ 2.6 ms ] story [ 331 ms ] threadScores: 50/55, then 53/55, then 55/55. Better to over-ID than under-ID (ask me how I know).
Well worth studying - and its habitat is spreading over time.
Climate change is not only expanding its habitat, but apparently increasing its urushiol content as it grows.
My mom had a brush with hogweed that gave her surprisingly bad sunburns many years ago. I keep away from most of the angelicas to avoid a similar reaction.
I recently learned about this tree in Florida where all parts of the tree can cause contact dermatitis, though not with urushiol. Even standing below it in the rain can cause rashes. https://en.wikipedia.org/wiki/Manchineel
Hogweed's super scary also. It's all over North America apparently. It contains furanocoumarin, a phytotoxin, and touching the plant sensitizes skin to sunlight. It can cause severe burns, necrosis requiring amputation, and permanent blindness.
A fact I just learned from looking it up: Species similar to giant hogweed, Heracleum mantegazzianum, are ALSO phototoxic. Did not know that! I thought if you could ID it as cow-parsnip or whatever, it was "safe." NOT. These include - Common hogweed, H. sphondylium -- Cow parsnip, H. maximum -- Wild parsnip, Pastinaca sativa -- Wild lettuces, Lactuca sp. -- Angelica, Angelica atropurpurea -- Queen Anne's lace, Daucus carota.
Other hogweed lookalikes in Apiaceae include the hemlocks, similar appearance but feathery leaves, which go WAY beyond phytotoxicity (all parts of the plant are fatally poisonous to humans).
Fun times. Steer clear! The cool thing about botany is, there's always something more to learn.
I removed a ton of Queen Anne’s lace from the yard when I moved in.
Now Texas bull nettle (Cnidoscolus texanus), while not extremely dangerous is instantly painful and quickly teaches you to give it a wide berth.
Worst advice from Boy Scouts ever.... But it stuck with me and helps me identify poison ivy.
We grow poison ivy as a cash crop, around here. You learn to recognize it.
It is everywhere. I once did a photo essay of a local abandoned insane asylum. Some of the buildings are covered with poison ivy, like English ivy (often, both).
Looks pretty in the fall, though.
ProTip: Don't burn it.
What happens when you do? Toxic?
I know a couple of landscapers that ended up in the hospital, because a few strands of poison ivy ended up in some brush they were burning (which they shouldn't have been, anyway).
https://pubmed.ncbi.nlm.nih.gov/35703240/
Also if you buy firewood, give it a once-over before tossing it into your firepit, fireplace, or campfire.
I know someone who had an older relative who did this back in the 1950s — they did a bunch of yard work, and figured they’d burn the waste. It turned out that this was a popular laundry day in the neighborhood when most houses had things drying on the line. After the third or fourth neighbor mentioned the mysterious rash, they realized what they’d done but wisely kept the secret for years.
Use shears and/or high concentrate vinegar. And if you are sensitive, find a friend that isn't.
Not everyone reacts to it, but when they do, it's pretty bad. The others I ate with have no reaction to it at all.
I have had it a couple times, with leaves brushing my skin. Huge, weeping sores all over my arms, chest, stomach (and worse), like leprosy (I imagine, anyways, never seen a photo of a leper). I can't even imagine eating it.
Similarly, I saw an episode of "Flavorful Origins" on Netflix, "Lacquer Seed Oil", which collected the fruits of the Lacquer tree (basically a poison ivy tree). They ground up the fruits and cooked the pressed oil to neutralize the urushiol (how did they not die from inhaling it??), and then they made a lovely tea with the oil with local bee larvae.
The best thing to come of it is a story of having "poison ivy chicken."
1) Irregular leaf shape. The leaves just don't know how to grow. Straight edge? Jagged edge? Both, neither?
2) The three leaves form a T-shape, with the center leaf jutting out.
Kudzu has its own issues, but it isn't a blistering agent.
https://www.nature.org/en-us/about-us/where-we-work/united-s...
The first indication I made a huge mistake was a relentless cough all that evening from the dust it generated as it broke off the tree. For the next month, I had horrible patches on my forearms and random other spots on my trunk where either it grazed me or I touched with my contaminated gloved hand. Luckily, I had some beta methadone lying around that helped the worst of the itching.
Even the dermatologist, when I saw him about 2 weeks post exposure, was horrified.
I've been exposed enough times that I need high dose of steroids, both topical and oral to knock it down.
Last time it took 3 rounds of steroids and clobetasol. Before I used to get by with triamcinolone.
I want this quiz, but for poison oak. There's so much blackberry and other stuff in the bay area that looks awfully similar. I'd rather learn how to reliably identify it than be afraid of ... everything.
The buds and stem tips are especially good giveaways, but I didn't really realize it until I lived somewhere with multiple species of sumac.
https://www.verywellfit.com/poison-oak-photo-4020320
> The leaves may be notched, round, or oak-like depending on what other foliage is around the poison oak plants. They may be shiny—or not. They may have a red tinge—or not. This is where the challenge of identifying these plants comes into play. ... > The actual shape of poison oak's leaves change based on the environment it is growing in, with the lobes able to vary on the same plant.
That may be why I've found it hard to pin down.
[1] https://en.wikipedia.org/wiki/Poison_ivy
People often ask me how to identify poison ivy. And I try to teach them. I think I do a decent job. It’s not as simple as one or two markers. But at some point you just develop an instinct
Poison ivy has a few distinct characteristics that make it hard to miss if you know what to look for.
I get asked to teach people plant ID sometimes, and people often seem mystified by it, until I explain the concept of "search image". It seems to give them a new way to approach it and seems helpful in most cases. Probably related to what you mean by "developing an instinct".
https://www.mushroomthejournal.com/the-species-concept/
Those stinkhorns tho :o
I know folks who always find arrowheads and fossils on hikes. Same skill, different patterns. This is a black box to me, I never see those things.
More generally speaking, plant identification is something I'm terrible at and really want to get better at.
It would be great if they had an alternate view for the ones that people get wrong.
I got 50/55. I think one of my big problems was not being able to tell textures from the photo, or not getting a clear view of the stems and runners.
https://www.walgreens.com/store/c/ivarest-poison-ivy-itch-re...
Luckily, my ignorance on this topic can be partly relieved for $7.
> Poison ivy gives most people an itchy rash.
Good thing I'm not one of those people. (Yet. Repeated exposure can apparently eventually make me one of those people. But I've made it a half century so far despite living on the east coast, being semi-frequently exposed while hiking, running, yard-work, etc, and never really worried about it.)
Meanwhile, my wife is a plant geek: 53/55.
Did you know that just clicking no for all of them will get you a higher score than this?
This is a good reminder for people. Most people only start getting it after a few exposures. I know of at least one early exposure that should have been really bad that nothing came of, but I've had it a few times since. I'm pretty careful these days though: 54/55.
...Now I know I'm going to get wrecked this summer.
I want a product that can show me where the oil is on my skin. I'm strongly affected by poison ivy. I sweat a lot, so I'm constantly touching my face. I've had bad rashes on my nose, eyebrows, and ears, amongst other places.
I use a soapy cloth every time I think I've been in contact and I still miss places.
https://en.wikipedia.org/wiki/Fels-Naptha
Even worse, it is almost impossible to find these days. The brand was acquired and the company that bought it is still ramping up production and distribution. Source: I emailed the company.
Actually just bought some Zote (also now owned by the same company), just yesterday, to test it out... but from what I hear, I don't think it is as good.
Discovering this site was a godsend for my son, who had severe eczema as a baby: https://www.solveeczema.org I would also get itchy skin hands after washing dishes, now, my skin feels great.
I've not tried using traditional soap for washing off poison ivy, though it does work for other kinds of grease, so I would expect it's ok as long as you scrub well enough with a cloth or something.
https://www.poison-ivy.org/seeleaf-detection-wipes
edit: PS: skip the dawn and use Gojo (the stuff from the autoparts store), or both.
He's right that scrubbing hard with a cloth is the most important part. For spot exposures mid-hike, a hard scrub with plain water in a stream or river, even without soap, has worked for me. A stone or a piece of bark can work as your scrubber. Better than your hand or your shirt. I swear that guy's saved me weeks of agony. Thanks for sharing.
extreme green power hand scrub is the same ingredients as zanfel, which is like $40 for a tiny tube. I keep tub of it in my shower and any time I see it starting, or think I may have come in contact I scrub the crap out of it, and it goes away in a few days. I haven't had a major breakout in well over a decade, and I reccommend it to everyone whenever the topic of poison ivy oak sumac or cashews comes up.
I have tons of it in my yard, and I'm genetically incapable of recognizing it by sight. I've gotten it 3 or 4 times in the past 10 years, and it's really annoying. I have some other type of vine, it's maybe kudzu but I'm not sure, that has completely enveloped trees, fences, climbing up my house. It's certainly intertwining with poison ivy and all the other plants and could very well pick up the oil from it.
There's an old movie called The Day of The Triffids, about walking/ambulatory plants, and you could shoot a remake of that in my yard and probably not need special effects. Kudzu can grow so fast you can almost see it in real time.
Three things work for me, in order of escalation:
1. Rubbing alcohol 2. Dawn dishwashing soap and scrubbing 3. Mean Green hand cleaner and more scrubbing
There was a scientist at UC Santa Cruz who patented a chemical that could be used to detect urushiol under a blacklight. I contacted them years ago to see if they were going to turn it into a commercial product, but AFAIK, it hasn't made it to market yet.
The idea is intriguing... a special light or cream to make urushiol visible on the skin to aid in scrubbing it off. Now that would be truly life changing!
For folks who don’t already know:
- three leaves in a cluster is a good warning sign
- redness of the stem where the cluster meets is a telltale
- the leaves generally have a point at the end, and may develop points along their sides
- dry looking roots going vertical is a bad touch, just… don’t bother unless you’re escaping some other danger
- If you’re like some of my family and get it from the wind, none of these guidelines have any value, I’m sorry!
Oh wow, I'd have to move. I have the stuff growing up many of the trees I walk under frequently.
I do get very bad reactions if I touch it.