One of the great things about this time of year is that, even after Halloween, people are racing to give you new ideas on ghosts, goblins, and how to kill people, with or without Nature's little helpers. Two articles from Atlas Obscura leapt out to me:
First of all, consider the Manchineel Tree*. Related to poinsettias, it's a nice looking tree, with fruit that looks kind of like the "little green apples" of the old Roger Miller song (older than dirt).
BUT:
You might be tempted to eat the fruit. Do not eat the fruit. You might want to rest your hand on the trunk, or touch a branch. Do not touch the tree trunk or any branches. Do not stand under or even near the tree for any length of time whatsoever. Do not touch your eyes while near the tree. Do not pick up any of the ominously shiny, tropic-green leaves. If you want to slowly but firmly back away from this tree, you would not find any argument from any botanist who has studied it. Supposedly it killed Ponce de Leon. (Manchineel Tree)
Gives new meaning to the Genesis admonition "if you eat of the tree you will surely die." Now I think that the average mystery writer can think of a couple of ways of utilizing the Manchineel Tree, with the help of say, some rubber gloves and mass disposal of all cooking utensils, and I'll just leave that idea simmering away in the back of your minds.
The Manchineel tree (Hippomane mancinella) is found in the Caribbean, Central America, the northern edges of South America, and south Florida. Florida, of course, is host to other toxic plants, including the spotted water hemlock, (Cicuta maculata, a/k/a spotted parsley, spotted cowbane, and the suicide root) which looks like this:
Occasionally mistaken for parsnips, this is considered to be North America's most toxic plant. "A quarter-inch of the stem is enough to kill a person" according to naturalist and botanist Roger Hammer, a naturalist and botanist. Unfortunately for us all, the range of the spotted water hemlock is the entire freaking United States, and I can show you a lovely crop growing up along the Big Sioux River here in Sioux Falls.
Or perhaps it's actually cow parsnip (Heracleum maximum), which grows everywhere, and is tall, herbaceous, and looks like a much larger, taller, thicker Queen Anne's Lace (daucus carota, a/k/a wild carrot). According to Alaska's Poisonous Plants,
"The sap of this plant contains various phototoxic chemicals that can make the skin (especially light skin) extremely sensitive to sunlight and more prone to sunburn. Skin contact with juice from the plant followed by exposure to sunlight can cause dermatitis, which can range from a mild, red rash to severe skin blistering."
Well, I'm not going to wade in to find out. But people actually ate cow parsnips and lived. From Wikipedia:
"The young stems and leafstalks were peeled and usually eaten raw, while early American settlers cooked the plant.[25] In terms of taste, texture, and nutrients, the peeled stalks resembled celery, which gave rise to the common name "Indian celery". The natives were aware of the toxic effects of the plant, knowing that if the outer skin were not removed, one would get an "itchy mouth" or blistering skin.[4][26] Pregnant women were warned away from the flower bud stalks to prevent newborns from asphyxiating when crying."
And this leads to (me, at least) the eternal question, how in the world did humans learn to eat some of this stuff?
But ginkgo is a more or less a garnish food. What's even more fascinating to me is when people take something that is absolutely poisonous and transform it into edibility through a long, involved process of grinding, boiling, rinsing, leaching, etc. - how in the world did they survive to find out that the product would be edible? Think about acorns and cassava.
And there's manioc, a/k/a cassava. Cassava root has cyanide in it, so it obviously has to be prepared carefully. Sweet cassava should be peeled, chopped up small, boiled until very tender, and the cooking water discarded. Bitter cassava (which is often grown because the animals won't eat it) has to be soaked in water for 4–6 days, boiled until tender, and then all the cooking water discarded.
Well, people aren't eating many acorns anymore, but cassava is the main carbohydrate for much of Africa and South America. And people are still getting poisoned by it: In 2017, 28 people died in Venezuela from cyanide poisoning from being sold raw bitter cassava roots instead of sweet cassava roots. (They look alike, apparently.) (El Pais)
"Nuts, roots and seeds! Nuts, roots and seeds! Come and get your fresh nuts, roots and seeds!""Hey, there, my husband tried that root. Took one bite and dropped dead, he did.""Well, madam, we don't guarantee safety. You could try cooking it.""Cook it? You didn't say nothing about cooking it.""Haven't you heard? Everything's better if it's cooked. Or ground up a bit.""My Aunt tried that. Ground it up cause she'd lost all her teeth. Took one bite and she dropped dead, too.""Well, I've heard that some people are chopping it up, and rinsing it a few times first.""How many times do you rinse it?"[Shrugging] "Trial and error. Depends on the root. You got any relatives you don't like to try it out on?""Well, there's me husband's crowd from the shore. Bunch of clam eaters.""And if that doesn't work, you could boil the hell out of it, and then drain it all off.""It all sounds like an awful lot of work. Don't you have any potatoes?""Not for another three thousand years. Meanwhile, you get this right, and you could have a nice bowl of tapioca pud for your tea.""Well, I suppose it would make a change... I'll take two. But mind, if this doesn't work, I'm sticking with cattails."