Dieffenbachia is a genus with quite a history, but you don't hear so much about the history these days. And, sadly, it's a really shameful, kinda sadistic history to boot (which is probably why you don't hear about it so much). If you're just here to find out how to grow them, and you don't care about any of the history and shame and torture and stuff, click over to part II.
The rest of you should just brace yourselves. I'm serious: this one might be a little tough to read, for people with sensitive constitutions. I mean, I tried not to go overboard with it, but there's a lot of stuff out there I'd never heard before, and some of it is kind of, you know, unpleasant, and has to do with what people have used the plant for in the past, and somewhat clinical descriptions of what happens when it's ingested, so, I dunno. Just don't say I didn't warn you.
Also, an opening acknowledgment: I am indebted to University of Florida Masters student Hui Cao, for her thesis, "The Distribution of Calcium Oxalate Crystals in Genus Dieffenbachia Schott, and the Relationship Between Environmental Factors and Crystal Quantity and Quality," which can be found as a .pdf file here. While a lot of what's in there is also reported elsewhere, it was nice to have confirmation of some of the wilder stuff, and also it's relatively clearly and coherently written, as scientific papers go.1 Good job, Hui Cao!
I really really really really want one of these. 'Tropic Forest' looks like
it has a lot of D. picta genes in it too. I could settle.
Most people who have been growing houseplants for any length of time know that Dieffenbachia spp. are poisonous. All parts of the plant, but especially the stalks, contain microscopic needles of calcium oxalate. These needles are irritating to skin (especially mucous membranes like lips and the inside of the mouth) on their own, but are more so if they're driven into the skin by the action of chewing.2 The skin responds to the irritation, usually, with swelling, reddening, and pain.
This is not normally fatal, and there aren't a lot of documented cases of people dying from chewing on a Dieffenbachia (there's at least one case, so it has happened before, but it's not so common that you need to start panicking yet. I'll tell you when you should start panicking, so be patient), but it can cause some fairly serious medical problems, especially if the throat swells so much that it blocks the airway.
I've read, over and over through the years, that one of the side effects of all this is that the tongue and throat can swell to the point where the victim may be unable to speak (not everybody mentions the airway thing), hence the common name "dumb cane" (and the somewhat less common "mother-in-law plant"). So far, so normal: most decent houseplant books and websites will tell you that much. What these descriptions often fail to mention, though, is that this is supposed to be excruciatingly painful, too. (Never mind that being in normal amounts of pain and not being able to say so would be plenty stressful all by itself.) I mean, it's not really something you'd give somebody to make them shut up: it's something you'd give to somebody if you hated them, or if you didn't think of them as being entirely human, or if you were just really incredibly sadistic.
But wait! It gets even better, because it's not just the crystals. There are also "proteolytic enzymes" involved. What's a proteolytic enzyme, you ask? It's an enzyme that breaks proteins down into smaller pieces. Your digestive system secretes three main ones, pepsin, trypsin, and chymotrypsin, which digest the protein you eat into pieces small enough to be absorbed through the lining of your digestive system. In the case of Dieffenbachia, then, this means that if you bite the plant, the sap will begin to break your skin, which, tragically, is made of proteins, down into its components, which means pain and (eventually) open sores. If the sap or stem or whatever is swallowed, then these open sores can be induced in the tissue of the esophagus and stomach, which leads to nastiness like vomiting blood and what have you. Worse still, there's one reported case (of a Brazilian man who decided, inexplicably, that suicide-by-Dieffenbachia was the way to go) here where someone who ingested some unspecified part of a Dieffenbachia couldn't keep down solid food for two and a half months after the incident, because his stomach was that riddled with holes.3
There are also thought to be extra chemicals floating around in the mix to make it all a little more painful, though this is (I gather) sort of controversial at the moment, and I was unable to track down any sites that positively identified any specific chemicals. A sort of allergic reaction may be involved as well; Hui Cao says that blood histamine (the main hormone mediating allergic responses) levels spike after contact with Dieffenbachia sap. Whether histamine is contained in the sap, or the sap induces one's body to release more histamine, I'm not sure, but either way, nothing that causes your histamine levels to increase is ever fun, as anybody who's allergic to anything can testify.
Considering that there are members of the Araceae (the family to which Dieffenbachia belongs4) which can be safely eaten if cooked (taro, Colocasia esculenta, is a staple food of people all over the world, and it's safe if cooked or soaked overnight in cold water), and considering that cooking doesn't actually remove or dissolve the calcium oxalate crystals, but it does deactivate proteins, my guess is that what's going on is, the crystals cut you up in order to give the enzymes better access to the tissues, so the plant can hurt you faster and more thoroughly. This could also explain why Dieffenbachia spp. seem to be far more dangerous than the other Araceae, which all also contain calcium oxalate crystals: it could be like cutting someone, on the one hand, vs. cutting someone and pouring acid in the wound, on the other. Both are clearly going to be bad, but one is going to be worse.
I wouldn't say that this means it's safe to give your kids peanut-butter-covered Aglaonema sticks as a snack before dinner; I'm just saying that there are different levels of danger here. If you have kids or pets who might be inclined to taste the foliage, move the Dieffenbachias out of their way, and do it now. (You may commence panicking now, if so inclined, though statistically, driving to the grocery store is more dangerous. So panic in moderation, if you can.) But rearranging the Anthurium collection, or putting a fence around your Spathiphyllums, is not necessarily something you need to worry about right this minute, even though they also have calcium oxalate crystals in them.
Getting the sap in your eyes is also, as you'd expect, extremely unpleasant, and is one of the occupational hazards of nursery and greenhouse work that hadn't even occurred to me until I started researching for this post. (I've been a lot more focused on the Agaves, since they've hurt me a lot more often.) I can't tell exactly, but it doesn't look to me like it causes long-term blindness or anything, just lots of swelling and pain and stuff, though the crystals can scratch the cornea, which would give one blurred vision, and scratched corneas probably are permanent.
So what I'm hoping you'll take away from this section of the report is: the Dieffenbachia genus is fucking serious about self-defense, and it is not to be toyed with, even if it's not likely to actually kill you. I don't know what the hell kind of herbivore would have made this necessary, but I bet there's some kind of hard-core arms race back in Dieffenbachia's evolutionary history somewhere.5
(I will admit, here, that in the past I have considered tasting just a little tiny bit of Dieffenbachia leaf, just to see how bad it really was – after all, what's a little muteness and swelling? Now that I've looked into the matter a little more, I'm glad I never tried it. Not that I think it would have killed me, just, you know, it seems like it would be really really unpleasant. I haven't vomited blood so far in my life, and . . . well, let's just say it's not on my bucket list.)
But anyway: it gets even worse. Of course. Remember several paragraphs back where I said it's the sort of thing you'd only do to someone if you really hated or dehumanized them, or if you just really enjoyed inflicting pain on people?
(I told you to brace yourself.)
Slave "owners,"6 in the West Indies, used to use Dieffenbachia to punish unruly slaves. I don't know how common this practice was, but it does seem to have been the practice: do a Google search for "Dieffenbachia slaves" if you don't believe me. On purpose, people would stick pieces of Dieffenbachia canes on and in the mouths of other human beings, for the purpose of causing them pain and swelling and muteness and difficult breathing and open oral sores and maybe even bloody vomit. Because they'd been "unruly." Or whatever. And maybe they had been unruly, a little bit, but then, if you want somebody to act civilized, transporting them to another continent against their will and forcing them to do hard physical labor for you under threat of torture is not, I think, the way to get that. I mean, you'd be unruly too.
I've also run across a reference to the use of Dieffenbachia sap in zombie-making, though I'm a little less certain about the reliability of that information. Voodoo priests aren't really known for publishing their zombification recipes,7 and even if they were, there's a lot of stuff that's thrown in there for dramatic effect, I think, not because it has any kind of real contribution to make to the recipe. So I dunno about that. But if it's true, I'll go out on a limb and say it's bad to bury someone alive and then force them to work for you after a few days when you dig them up, whether you include Dieffenbachia material as part of the recipe or not.
And of course no list of dehumanization is complete without Nazi Germany: there are rumors that Dieffenbachia extract of some kind was being investigated in the concentration camps as a possible agent for sterilizing populations. I'm not quite sure about that one: the idea pops up a lot that Dieffenbachia is related in some way to sexuality, but it's not consistently reported, and not only does nobody seem to know how that might work, but nobody seems all that interested in finding out, either. But even so: there are some glancing references to it causing temporary infertility, and in other cases it seems to be curing erectile dysfunction.8 But then, I didn't say the Nazis found that it worked, just that they were looking into it. They looked into a lot of things. Unfortunately. Hui Cao says that the experiments were limited by unavailability of Dieffenbachia in Germany at the time, which I guess was a good thing? Or not? Which would you prefer: torture by Dieffenbachia, or the gas chamber? And isn't it, really, an awfully dumb question?
There's at least one reported case of Dieffenbachia being used to prevent a crime victim from testifying in court (quoted from Cao):
Barnes and Fox (1955) also chronicled an interesting story (Kremmens, 1952) of Dieffenbachia being rubbed into the mouth of an eye witness to a crime by the culprit, and when the witness was called into court in the Bahamas, he could not testify and the criminal was acquitted.
(What, they couldn't have the witness write shit down? Testimony doesn't count unless it's verbal?)
It makes me kind of uncomfortable to know all this. I've always liked Dieffenbachias, and it's weird for me to find out that for some other people, long ago, they would have represented punishment and pain and degradation and – holy crap – concentration camps and so on. I mean, not that a lot of other things didn’t represent that too – the world in general kind of sucks when you're a slave, or a zombie, or a Jew in Nazi Germany,9 and I'm not saying that any of these groups necessarily singled out this one plant for some kind of special symbolic significance. And yet, I don't know: a little swelling and muteness between friends where nobody gets permanently damaged is sort of funny - in a dark way, sure, but funny nevertheless. But forcing somebody to vomit blood and eat through an IV for two and a half months is never funny, in my opinion.10 It makes it symbolic for me, I guess, kind of irrespective of what the actual slaves (or zombies, or Jews) felt about the plant at the actual time when this was going on.
All these years, you think you know a plant, and then you find out something like this. I feel like saying to the plant, I don't even know who you are anymore.
On the other hand, I suppose going from instrument of torture to decorative office plant is an improvement, kind of a swords-to-plowshares progress. Maybe it's being rehabilitated.11 Let's find out, in Part II of this post.
Photo credits: mine unless otherwise identified.
1 I suppose "clear for a scientific paper" is damning with faint praise, but I don't mean it that way. Also: small world: Cao thanks Dr. Richard J. Henny for his assistance in providing experimental materials and growing instructions. Dr. Henny is, of course, better known to long-time PATSP readers as Plant Daddy. I don't think Dr. Henny is aware of me, or PATSP, and he's not likely to be anytime soon, I think, because he doesn't allow comments on his blog and I have nothing coherent to say to him in an e-mail,a but I was a little shocked to recognize his name while I was reading through the thesis. Oh my God!!! That's Plant Daddy!!! She knows Plant Daddy!!! I'm sooooo jealous!!!
aDear Dr. Henny,
I'm a huuuuuuge fan of your work, especially Dieffenbachia 'Sterling,' and I'm wondering if you have any job openings down there for someone with a lab background, high tolerance for tedious, repetitive tasks, and plenty of raw enthusiasm, but absolutely no heat tolerance, experience, or training in the stuff that you actually do. I guess what I'm saying is, I would like to make [aroid] babies with you. Alternately, if you could maybe just ship me all the Dieffenbachia and Aglaonema rejects, that would also be awesome.
P.S. Anthurium 'Red Hot' rocks.
2 They're also supposed to be sort of spring-loaded, which is to say that the needles are constructed in such a way that they actually fire themselves into your tender, sensitive flesh when the plant is bitten. I wasn't enormously interested in this part, and therefore didn't look into it closely, but if you are, I suggest you check Ms. Cao's thesis, 'cause I'm sure it's in there.
3 Which, if he'd wanted to commit suicide before eating the leaf, you can imagine how much he would have wanted to once he was getting fed through IV (I assume) for two and a half months. In fact, you'll pretty much have to imagine it, since as far as I know nobody's asked him about it on the record. I'd kinda like to discuss it with him, though, as I am inordinately curious about why someone would settle on this suicide method in the first place.
4 Including such gems as Aglaonema, Homalomena, Philodendron, Anthurium, Alocasia, Colocasia, Spathiphyllum, Zantedeschia, Caladium, Epipremnum, Syngonium, etc. Philodendrons are actually reported to poison control centers a little more often than Dieffenbachias are, but I'm guessing this probably has more to do with philodendrons being a more popular, more abundant plant, not because they're that much more dangerous.
5 Arms races are relatively common in evolution, it appears. One of the most fantastic has to be that between a population of newts and garter snakes along the west coast of North America: the end result of it is a newt about 8 inches long that routinely produces enough poison to kill 10-20 adult humans, and a garter snake that can go ahead and eat the newt anyway. See article here for details. The crystals, plus the proteolytic enzymes, plus the possible other chemicals to make it all more painful, are collectively pretty over the top; I'd be shocked if this weren't mostly aimed at one specific plant-eating threat. Though I've been shocked before.
6 Scare quotes because I find "owning" a person a questionable concept. I know it's been legal before. That's not what I'm talking about.
7 ("Add six cups of agitated centipede and fold in until mixture forms stiff peaks. Chill in refrigerator, then add chopped scorpion and pufferfish. Garnish with parsley, if desired. Serves six zombies.")
8 (In the style of a poorly-acted 1950s ad:)
JANE: I just don't know what to do about my Robert. We've been having intimacy troubles, you know, and nothing I try seems to work.(Obligatory disclaimer: I do not advocate poisoning anyone with Dieffenbachia juice, ever, under any circumstances.)
BETTY: Have you tried Dieffenbachia?
JANE: Why no. Tell me, how do you use it?
BETTY: You just slip a little bit of the sap into his morning coffee, and by the time he gets home from work in the afternoon, he'll be frisky as a newlywed.
JANE: Well it sounds wonderful, but – are there any side effects?
BETTY: Oh sure, sure. John's been vomiting blood for six months and has to be fed through an IV. But our sex life's never been better! I don't even have to use contraception! And he doesn't talk anymore! And I only have to cook for myself now!
JANE: Gosh. That sounds like the answer to my prayers! I think I'll try it!
9 (and especially when you're a Jewish zombie slave in Nazi Germany)
10 (well, maybe once.)
11 (I say that now, but just you watch: within a couple months I'll run across a page somewhere that's talking about how people are torturing one another with Dieffenbachias somewhere in the world right this minute, and then I will despair. Humans have many fine and attractive qualities, and it's not like the chimps or the dolphins are creatures of pure and noble goodness either, but all the same, sometimes I wonder if the world really needs more people. Or any people.)