
I'm on a deserted island. How can I tell which plants are poisonous?   - yanowitz
http://www.straightdope.com/columns/read/2919/im-on-a-deserted-island-how-can-i-tell-which-plants-are-poisonous
======
fernando
My all time favorite answer for this question is from a book I read in Brazil.
It was a jungle-survival guide from a Brazilian military:

First of all, find a monkey. Follow the monkey, and eat everything the monkey
eats. If possible, eat the monkey too.

~~~
reginaldo
There are of course variations of this trick. If you can't find a monkey,
either a quail or a toucan will do just fine. I have some friends who were in
a military survival training mission in the Amazon.. For many days all they
were able to find was swamp cabbage (palmito). Then they found a toucan... The
monkey trick didn't work because the trees are very very tall.

~~~
whyenot
Energetically, I bet you'd spend more calories following the bird than any
calories you'd gain from food you collect. On the other hand, I've been told
that toucan is quite tasty.

~~~
TrevorJ
Although, once you found the locations you could remember them or map them and
then later trips would be more efficient.

~~~
whyenot
Yes, but that probably isn't enough of a savings. We don't have a toucan's
digestive system, and can't process large amounts of fruit quickly through our
digestive tract like they can. It's a case of starving with a full stomach.

------
Tuna-Fish
The simple rule I was taught that if you can find anything that moves, cook
and eat it before eating unknown plants. Your odds are generally much better
with animals than plants -- you can probably find dozens of examples of
inedible or poisonous plants on your back yard alone, while poisonous (as
opposed to venomous) animals whose poison is still dangerous after being
cooked are quite rare.

An even simpler rule is to start with anthills -- ants live almost everywhere,
and while many ant species use poison as a weapon, none are poisonous after
cooking.

~~~
billswift
A caution here is that some fish, especially in tropical areas, are poisonous.
Any mammal or bird can be eaten, some reptiles are poisonous though - box
turtles, for example, can retain poisons absorbed from their food.

~~~
ghshephard
"Any mammal or bird can be eaten"

<http://en.wikipedia.org/wiki/Venomous_mammals>

...some birds are poisonous to eat or touch, such as the pitohui, the ifrita,

------
ryanwaggoner
I love how this guy clearly has no idea what he's talking about, relies
primarily on a single source (US Army Survival Manual) that's based on decades
of research and experience in these kinds of life-and-death situations, then
proceeds to disagree with the source on multiple points. So much for fighting
ignorance...

~~~
metra
Cecil does know what he's talking about. The Straight Dope is a website based
on people submitting questions to Cecil who, in turn, does the research and
presents the findings for you along with some of his trademark witticism. It's
been a wildly successful website.

The readers know the premise - that Cecil, not an expert but definitely a
pretty smart guy - is doing the work for you. And given the wealth of
information presented in such a digestible form, I'd say that's fighting
ignorance indeed.

~~~
ryanwaggoner
_The Straight Dope is a website based on people submitting questions to Cecil
who, in turn, does the research and presents the findings for you along with
some of his trademark witticism. It's been a wildly successful website._

That's exactly my point: he did a little research, found one primary source
upon which to rely, and then proceeds to disagree with that source, based
solely (as far as I can tell) on his opinion. Why wouldn't I just listen to
that source directly, which is based on actual expertise?

And its success is completely irrelevant to whether he knows what he's talking
about.

------
forinti
There's a show on the Discovery Channel about people who get lost in the
wilderness. One thing I've noticed is that they spend all their energy and
time trying to get back to civilisation, so they very rapidly get worn down.

I think a good strategy when you are lost in the wild is to immediately start
keeping an eye out for shelter, food, and water. The article gives some good
tips, but they take time if you want to be reasonably sure of what you are
going to eat.

~~~
streety
There is a saying that, "you can travel across the land or live off the land
but not both."

You may be able to improve your chances over the short term by concentrating
on finding food but if you want to survive long term your best chance may be
to get back to civilisation and get back quick.

Having said that as with most situations the optimal strategy is probably
somewhere between the two extremes.

~~~
a-priori
If you have no idea how to get back to civilization, your best strategy is to
wait for search and rescue. Wandering aimlessly is the worst thing you can do.

~~~
adrianwaj
Also, you want to try and make a signal to any rescuers or passers by.

Try chopping down trees in a pattern so planes can see the pattern. Have a
bonfire ready that can be lit in less than a minute if you hear a plane or
helicopter, or see a boat. A mirror too can be reflected out to people.

~~~
a-priori
Yes, the universal symbol is to make an X in an open area with branches or
something. A smoky fire is also a good idea.

------
aarongough
One thing not mentioned is what you're looking to avoid when you're conducting
the UET.

When testing skin contact beware of:

* Rash

* Hypersensitivity (to touch or light)

When testing by contact with the lips and chewing beware of:

* Numbness or pain

* Spicy flavour, heat or burning sensation

* Any hint of a taste of almonds (as mentioned: Cyanide. Not a good idea)

This is by no means complete, the 'SAS Survival Guide' has some good info on
this topic, though other parts of that book should be taken with a grain of
salt...

~~~
GiraffeNecktie
Don't forget to wait. Poison ivy might not show up till the next day.

------
maxklein
Okay, someone a bit more intelligent than me should correct me on this:

Are most poisonous plants not bitter or foul tasting? Also, apart from
mushrooms, don't they usually signal their poison?

Why does a plant develop poison if not to discourage animals from eating it :
and if it does not signal through taste or look, how would an animal know?

I know nothing about this topic, I'm actually curious.

~~~
billswift
Many wild plants are bitter while being perfectly edible - pokeweed, for
example, is widely eaten despite being rather bitter without preparation (it
is still edible even raw, I've munched on it often when hiking as a teen).
Others are perfectly tasty while being poison, some will just make you sick,
but wild almonds are supposed to taste like domestic ones, but have enough
cyanide to kill a child outright.

~~~
nkurz
All other sources I have found suggest that mature poke leaves are poisonous
until cooked. I'm not sure if Bill is a troll, wrong, or just of solid
constitution, but please do your own research before taking his advice on wild
edibles.

ps. I've also seen no one else claim that "wild almonds" taste like domestic
almonds: "not even the most ardent nut lover among us will eat wild almonds;
their lousy taste keeps us away"
<http://discovermagazine.com/1994/sep/biologyandmedici422>

~~~
billswift
I've seen claims both ways on leaves - poisonous and not - I've only eaten
them cooked and don't particularly like them. The young stalks are the only
part universally agreed not to be poison, that is the part I have eaten often
(older stems gain poison later - rule of thumb is not to eat them after they
start turning purple, though I have eaten them up until they started getting
woody without problems). Some sources claim the berries are poisonous some
claim not, but I grew up being told they were poison and have never tried
them. And the root is universally agreed to be seriously poison.

------
fjabre
Even with a survival manual it's easy enough to get one harmless food source
mixed up with another look-alike harmful one.

It's widely speculated that this happened to Chris McCandless aka Alexander
Supertramp, who hiked into the Alaskan wilderness back in the 90s to get away
from it all but ended up dying from either starvation or eating something
poisonous which contributed to his starvation..

I guess the point is get ready to kill some small animals and go fishing. The
idea that a couple of "Castor bean seeds" could be fatal is enough for me to
consider all plant life poisonous unless I'm 99% positive it's a lemon or an
apple or something like that, something well known...

~~~
rdtsc
Wiki page on McCandless: <http://en.wikipedia.org/wiki/Christopher_McCandless>
The speculation is that he died either from eating
<http://en.wikipedia.org/wiki/Hedysarum> or Hedysarum with "Black Patch
Desease" fungus : <http://en.wikipedia.org/wiki/Rhizoctonia_leguminicola>

I just watched the movie about him "Into The Wild" -- pretty interesting.

~~~
adrianwaj
He died in the Denali National Park:

"Wild blueberries and soap berries thrive in this landscape, and provide the
bears of Denali with the main part of their diets. Over 450 species of
flowering plants fill the park, and can be viewed in bloom throughout summer.

Unfortunately, the spring and summer months are short."

[http://en.wikipedia.org/wiki/Denali_National_Park_and_Preser...](http://en.wikipedia.org/wiki/Denali_National_Park_and_Preserve)

Edit: his journal was called "Beautiful Blueberries."

------
indrax
Look for the plants that other animals are eating, use them as bait, eat the
other animals.

------
stcredzero
Reminds me of a theory I came up with awhile ago. Why do little humans have
such a strong propensity for sticking everything in their mouths? Well, way
back when in the stone age, infant mortality was high. Mortality among the
newborn is high for many species. As a result, low tech-level human
communities don't invest in a little individual until they make it in the
world for awhile. In fact, the little buggers haven't really had _that_ many
physical resources devoted to them. It takes a lot of food to make a baby. But
that's peanuts to the resources invested in an adult over 2 decades of life.
So who should be the food taster? Who should try things out to see if they're
safe to eat? That's right, all those little ones!

It actually makes evolutionary sense for little humans to want to stick random
things in their mouths and so become unwitting food tasters. It's better for
the community, overall.

(Also, it puts pressure on mothers to be _attentive_! Another benefit to the
community.)

Lots of female friends of mine _absolutely hate_ this theory. I can understand
why. But nature isn't always so nice.

(And yes, this theory is actually testable!)

~~~
Confusion
The theory may very well be true, but it isn't very helpful. Firstly, you
probably won't have an infant around when you get to that deserted island and
secondly, if you do, it's probably your own and you'd rather die yourself than
watch your child die. Of course the latter is stupid, because the child will
die if you die, but humans aren't rational beings.

~~~
stcredzero
_The theory may very well be true, but it isn't very helpful._

Theory is a tangential discussion of food tasting and not meant to be applied
to this specific context. Applying it so would be not too smart. I hope you're
not making conclusions by projecting your own thought processes.

------
whyenot
_Boil it, if you've got the means. The army disparages this practice, saying
boiling doesn't destroy all toxins. Maybe not, but it'll destroy some toxins,
and at the same time get rid of the tannins that render foods like acorns
unpalatable._

Boiling doesn't get rid of tannins. Native Americans poured boiling water over
ground acorns to leach out _some_ of the tannins.

------
inglorian
Another useful rule is that all grasses (and their seeds) are edible. Not
particularly tasty or nutritious, but they won't kill you.

------
gcheong
Hmm, nobody mentions eating the insects or digging for grubs but I've seen
this done on "Man vs. Wild".

------
lacrossegm
Water is more important than food. A person can go a long time without food,
but will die without water in just a few days time.

I would observe what the local animals seem to be eating.

Another trick is to take a sample and rub a bit of it on of your skin. If it
causes irritation, its probably bad.

~~~
joelhaus
Here's an unpleasant thought; what are the rules for drinking your own urine?
Some apparently do this for fun, but what about for survival situations?

If you're able to find enough edible plants (via watching other animals), it
might also be worth trying to cultivate them, but this depends on your broader
circumstances.

~~~
RS14
Don't expect to stave off dehydration by drinking urine. Your body expels
salts (and other substances) through urine. Thus you'll die from hypernatremia
drinking urine or seawater, just as happens if you don't drink water at all.

Apparently blood and alcohol are also bad. They are processed as food, which
requires large amounts of water from your body. Thus while they're both
fluids, they result in a net loss of water.

Fish apparently have a column of fresh water near their spine. You can cut
them open and drink from this. You can also suck fresh water from their eyes.

Edit: Oh, hey, a citation:

<http://en.wikipedia.org/wiki/Urophagia#Attempting_survival>

Everything else is from "Complete Survival Manual," Michael Sweeney.

------
dkersten
I got myself a copy of the SAS survival handbook sometime last year. It covers
this topic and many others: [http://www.amazon.com/SAS-Survival-Handbook-
Revised-Situatio...](http://www.amazon.com/SAS-Survival-Handbook-Revised-
Situation/dp/0061733199/ref=sr_1_1?ie=UTF8&s=books&qid=1264167645&sr=1-1)

~~~
billswift
There are a _lot_ of books with this advice in them. It could even have been
cribbed from my Boy Scout Handbook from back in the 1970s.

------
johnl
I would collect everything an animal might want to eat, place them in distinct
piles and watch what comes around and what is eaten. You can then form a
strategy based on the animals sited or just eat what they do, working up from
very small portions.

------
tobych
Not about survival as such, but the "Plants for a Future" project catalogues
7000 "rare and unusual plants, particularly those which have edible, medicinal
or other uses."

<http://www.pfaf.org/>

------
a-priori
One tip I learned for berries was that if the birds don't eat them, you
shouldn't either because they're almost certainly poisonous. The reverse is
not true: birds can eat things you can't.

~~~
CWuestefeld
Bottom line: If there's any there, it's not safe to eat it. If they're all
gone, then they would have been safe.

Next chapter, how to test for witches by the flotation method.

~~~
billswift
>If they're all gone, then they would have been safe.

WRONG. Birds can eat a lot of things that would make you very sick.

------
Mz
_How do I know what I should eat and what I should feed to my mother-in-law?_

I haven't seen this point addressed, neither in the article nor in this
discussion. But does it sound to anyone else like he is implying that he wants
to live but would like to poison his mother-in-law? (I know it's cliche, but
the phrasing sounded odd to me. Maybe it was intended humorously.)

------
sirbyt
Apparently you have an Internet connection. Look it up on Wikipedia.

------
poutine
If you must eat plants and can't watch the animals then:

Spread a bit on your skin, wait a while to see if there's a rash. Touch some
to your lips and tongue, again waiting a while to see if there's a reaction.
Eat a tiny bit, wait a while. Eat a larger bit and then wait. Continue upping
the dose.

This is from memory from the SAS survival guide. Should take days and isn't
very safe but may be the best you've got.

~~~
JshWright
This sounds vaguely familiar... like I just read an article with this advice,
or something...

~~~
poutine
Ah, yeah I should have read the article. Oops.

