# How do I tell which plants are poisonous? **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [January 23, 2010, 7:23pm UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149 "2010-01-23T19:23:30Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [February 3, 2010, 2:55am UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149/21 "2010-02-03T02:55:19Z")
Why would a monkey be able to eat something a pig and a human cannot? :dubious: Cite? Though many places you are far more likely to find pigs than monkeys. Of course, if you find either pigs or monkeys, you probably don’t need to worry about what they are eating - eat them! ---
**Author:** ![Carptracker](https://avatars.discourse-cdn.com/v4/letter/c/ac91a4/32.png) [@Carptracker](https://boards.straightdope.com/u/Carptracker)\ **Post date:** [February 6, 2010, 1:47am UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149/22 "2010-02-06T01:47:35Z")
> [@Irishman](#): > > Why would a monkey be able to eat something a pig and a human cannot? :dubious: Cite? > > Though many places you are far more likely to find pigs than monkeys. Of course, if you find either pigs or monkeys, you probably don’t need to worry about what they are eating - eat them! Except both will be much more difficult to eat than a nice piece of fruit. I mean, a pig or a monkey normally won’t just lie there and let you pick it up and chew off a mouthful. And unless you are marooned with a a firearm or are very good at devising and using other lethal methods, you might starve to death trying to catch one. That is why I am going to catch a fish, when I am marooned on a desert island. I am very good at catching fish, with a variety of means, and there are very few that are poisonous (but stay away from the puffers). By the way, Chronos beat me to it on the cashews. But the fruit part is not that bad. You can handle the skin on the domestic ones without getting a reaction, unless you are remarkably sensitive, and some people can even eat skin and all without problems. I have. But NEVER, NEVER, try to bite into the leathery husk surrounding the cashew itself. The result will be a spray of liquid that can literally take substantial parts of the skin off your face. Seen it in more than one Peace Corps volunteer that did not get the message. ---
**Author:** ![Carptracker](https://avatars.discourse-cdn.com/v4/letter/c/ac91a4/32.png) [@Carptracker](https://boards.straightdope.com/u/Carptracker)\ **Post date:** [February 6, 2010, 1:52am UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149/23 "2010-02-06T01:52:42Z")
By the way, I think mangos might have more urushiol in the skin than cashews. Cashews have way more, of course, surrounding the nut, but mango skin can be a lot more problematic than cashew apples, in my opinion. My wife can’t touch or eat mango because of it. ---
**Author:** ![Maryna](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@Maryna](https://boards.straightdope.com/u/Maryna)\ **Post date:** [February 9, 2010, 3:37pm UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149/24 "2010-02-09T15:37:02Z")
> [@Christopher\_K.Starr](#): > > You were right to note that the digestion of other species isn’t the same as our own, but for the most part you can eat the fruits that another vertebrate animal eats, especially a mammal. I’d be weary of following the lead of small rodents: after all the rats are still with us and not for the want of trying to poison them out of existance. The local herbivores would have time and motivation to develop resistance, so they are out as well (apart from veggie monkeys). OTOH, carnivores are generally more sensitive to plant toxins then us, but the survival value of following a tiger to check which grasses it munches on might be questionable. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [February 9, 2010, 11:16pm UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149/25 "2010-02-09T23:16:06Z")
That’s no so much a lack of susceptibility to poisons as it is the fecundity of rodents. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [February 10, 2010, 11:00am UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149/26 "2010-02-10T11:00:29Z")
> [@Christopher\_K.Starr](#): > > I have occasionally come upon a fruitfall in the forest, seen that many fruits had been nibbled by animals, and then partaken, never with seriously untoward results. You’ve been lucky. I suspect that you also live in the northern temperate regions, where most plants are weeds due to evolutionary and climatic reasons. Try that trick outside of the northern temperate regions and you stand a very, very good chance of dying. > [@](#): > > … for the most part you can eat the fruits that another vertebrate animal eats, especially a mammal. That is so far from being true that it is almost criminally dangerous to even suggest such a thing. Birds and grazing mammals will both happily eat a huge variety of fruits that will kill a human stone dead in under 12 hours. At the most extreme, macropods will eat plants loaded with fluroacetate, a substance so acutely toxic and so irrversible that it has been banned for use as rat poison. Parrots go one better. They will eat \*Eythrophleum \*leaves, a food os poisonous that just a few grams will kill a full grown horse stone dead. yet a 10 gram parrot will eat a quarter of its body weight of the leaves in one day. I can only repeat what Cecil said and hope that it sinks in: the digestion of other species isn’t the same as our own. For the most part, if another vertebrate animal eats it it’s about as likely to poison you as a plant which it doesn’t eat. > [@](#): > > Look at it from the plant’s point of view. There is a biological reason why many plants produce luscious-looking fruits. It serves to attract animals, who consume the fruits, usually in such an untidy way that many of the seeds are dispersed away from the under the parent plant. It is in the plant’s interest for animals to eat the fruits and to do so without ill effect. No. it isn’t. As others have noted, it’s in the plant’s interest for some, often only one, animal to eat the fruit. If humans arent; that animal then you are dead. Want to try eating some[lucscious looking grapes](http://upload.wikimedia.org/wikipedia/commons/2/27/Melia_azedarach_fruits.JPG)? How about a [luscious looking cherry](http://www.sgapqld.org.au/images/Rhodomyrtus-macrocarpa-2.jpg)? How about these [luscious, fleshy berries with a wonderfully textured nut kernel inside](http://image10.webshots.com/10/6/1/56/131760156TURMZr_ph.jpg)? Those are just three plants growing within 3 miles of where I am now sitting. I will tell you that all produce brightly coloured fleshy fruit and all are commonly eaten by vertebrate animals. Want to try guessing which are toxic and which aren’t, and what the effects will be if you are wrong? If you can’t answer this question you will hopefully begin to see how dangerous it is to claim that for the most part it’s safe to eat fruit that other animals eat, or that brightly coloured, fleshy fruits are designed to be eaten by all animals. In fact many brightly coloured, fleshy fruits are deadly poisonous. And some are worse. > [@](#): > > I’m not saying that one can eat any ripe fruit with impunity, but fruits probably provide the surest food source if one is in dire need in a strange place. Actually you are probably better off eating the reproductive parts of the plant. Plants put so much energy into producing fruit, they are available for such a short period and they are targeted by so many species that the most potent defences are usually found in the fruits. In contrast so few animals eat vegetative organs and they are available for so long that the toxins are usually relatively mild, result in chronic poisoning and are often physical or irritant in nature rather than physiological. IOW my educated guess is that fruits are probably the absolutely the worst bet if one is in dire need. > [@Irishman](#): > > If something is scarce because it is frequently eaten, that speaks well of its potential as food. Not in any way that I can understand, nor in my experience. The most widespread and common plants are those that are dispersed readily. That is why so many weeds have highly edible fruit. If a fruit is eaten widely then it will be dispersed widely and the pant will become more common. If a pant is scarce because it is frequently eaten then it is because something is eating vegetative parts or the flowers. That tells you nothing at all about the edibility of the fruit. Most legumes are scarce because they are frequently eaten, but there fruit is deadly poisonous. > [@Fear\_Itself](#): > > My point was, there is probably a reason said plant is plentiful. If the indiginous species won’t eat it, that is a powerful reason to avoid it as well. That I can agree with. Big difference between “If the locals eat it, you can too” and “If the locals avoid it you should too”. > [@qazwart](#): > > Fruits that mammals chew tend to be larger in size with very bitter seeds. I’d have to see a reference before I would believe that. It just isn’t true in my experience. Birds and mammals eat fruits of all sizes with about the same frequency in my experience. A mynah will eat a mango or a banana just as readily as a monkey or a possum. A bear will eat a blueberry or a rasberry just as readily as a starling. I really can’t see any factual basis to a claim that fruits eaten by mammals are larger or with more bitter seeds than those eaten by birds. > [@](#): > > Color might be another clue: Avoid bright red stuff. Mammals can’t see red, but birds can… Many malls can indeed see red. > [@](#): > > … and birds cannot eat larger fruits. Can you please provide some evidence for this claim? Which large fruit can birds not eat? Which large fruits don’t birds eat? Jackfruit, bananas and mangoes are among the larger fruits that spring to mind, and all are regularly eaten by birds. I honestly can not think of a single large fruit that birds don’t eat but that mammals do. > [@](#): > > . If that person doesn’t die with in the next eight hours, it’s safe for you to eat. Ahhh, no. Many plant toxins take days or even months to show symptoms. The enzyme and vitamin inhibitors are the classic example of this. A great many legumes are absolutely lethal, but you won’t show any symptoms at all for weeks. Many of the neurotoxins and carcinogens also won’t exhibit symptoms for a long time after ingestion. > [@](#): > > Anyone can think of a large fruit that isn’t safe to eat? > **[Maclura pomifera](https://en.wikipedia.org/wiki/Maclura_pomifera)** > > Maclura pomifera, commonly known as the Osage orange (/ˈoʊseɪdʒ/ OH-sayj), is a small deciduous tree or large shrub, native to the south-central United States. It is a member of the mulberry family, Moraceae. It typically grows about 8 to 15 m (30–50 ft) tall. The distinctive multiple fruit resembles an immature orange, is roughly spherical, bumpy, 8 to 15 cm (3–6 in) in diameter, and turns bright yellow-green in the fall. The fruit excretes a sticky white latex when cut or damaged. Despite D... > [@dork\_chocolate](#): > > If you’re stuck on a deserted island, look for wild pigs, because if a pig can safely eat it, a human can. More hideously dangerous advice. Pigs commonly eat cycad fruit which are lethal to humans. If a pig can safely eat it, it can still kill a human within days. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [February 10, 2010, 10:17pm UTC](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149/27 "2010-02-10T22:17:59Z")
**Blake** said: > [@](#): > > [QUOTE=Irishman] > If something is scarce because it is frequently eaten, that speaks well of its potential as food. Not in any way that I can understand, nor in my experience. [/QUOTE] My point was _not_ to eat what you see other animals eating, my point was that it does not do you much good to starve to death looking for raspberries because you know you can eat them if everything else eats them, too, and gets there first. If something is scarce, it is probably not worth your effort to find out if you can safely eat it. If you are going to go through the 3 day process to test something, test something that you have a chance of finding enough of to keep you alive. > [@](#): > > If a pig can safely eat it, it can still kill a human within days. I’m still waiting on a cite that humans’ digestion is closer to pigs’ than to monkeys’. [Previous page](https://boards.straightdope.com/t/how-do-i-tell-which-plants-are-poisonous/526149.md?page=1)