Wednesday, April 30, 2008

Sadist (Dieffenbachia spp.), Part I

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.

Dieffenbachia 'Tropic Rain.'

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!

Dieffenbachia picta, like it says. Photo credited to "Tequila," at Wikipedia.
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.

Dieffenbachia NOID. It's a little too small yet to see what the variegation pattern is going to be (it was a Lowe's rescue), but it looks like it might be 'Parachute.' Click to enlarge.

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.

Dieffenbachia 'Tropic Snow.' Photo: "bingregory" at flickr.com.

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.)
I think this is Dieffenbachia 'Triumph.' co-planted with 'Tropic Honey,' but it's hard to tell. This is a combination of a plant from work and a rescue plant from Lowe's, so they're not necessarily the same variety. 'Triumph,' grown in ideal conditions, will get a very narrow, precisely-drawn green ring around the outside of the leaf, and 'Tropic Honey' looks like 'Camille' but with more white and larger leaves: the boundary between white and green is much more gradual with 'Tropic Honey' than with 'Triumph.' The leaf furthest back in the photo, which looks like it is almost entirely white, is more or less typical for a 'Triumph.' Of course it's also typical for 'Tropic Marianne,' too, which is a whole other thing, and there's an old variety called 'Rudolph Roehrs' which kinda looks like that too, though I think it has smaller leaves. In any case: I call this one 'Triumph' at home, but the odds are that I'm at least half wrong.

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?

Dieffenbachia 'Camouflage.'

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.

Love, Mr_Subjunctive.

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.
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!
(Obligatory disclaimer: I do not advocate poisoning anyone with Dieffenbachia juice, ever, under any circumstances.)
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.)


18 comments:

Nancy J. Bond said...

How very interesting! I knew this plant was on the list of toxic-to-pets, but never knew it was THAT toxic! Me thinks I'll just stay away from them with an adventurous cat and small grandchild. :)

Mr. Green Genes said...

Hi Mr. S,

You may not have been stupid enough to try the effects yourself, but somebody else did.

I quote from "Once upon a windowsill" by T. Martin (a rather unremarkable book, btw):

<<...Alexander von Humboldt (1769-1859) who originally collected the plant in the Tropics. Although the natives warned him of the plant's silencing powers, he was skeptical. Curiosity drove him to sample the plant, and his disbelief was ultimately rewarded by a loss of speech which lasted several days.>>

Sometimes in Rome you just have to do what the Romans do, and abstain from silly experimentation, I guess.

From Aroids by D. Bown one gathers the interesting fact that in the UK alone between 1983 to May 1987 there were 183 cases of poisoning (usually minor, and among children under 5) reported. That is much more than the 206 cases (181 children, 11 adults and 14 animals) reported in a 13-year period in The Netherlands. Maybe British children are more inquisitive than Dutch ones?

Best, Mr. GG

Water Roots said...

Great post! Your sense of humour shines through even in the midst of all the oodles of serious information. You should be a teacher, especially college level. Kids would line up around the block to sign up for your courses!

Paul said...

I wouldn't think that taro had the crystals at all -- considering how many people eat taro. If it also had the sharp crystals, twould seem odd for it to have become a staple of so many diets.

Hmmm, I wonder what herbivores DO eat Dif. -- you know there must be ones that do or Difs would have "taken over the world" :)

Anonymous said...

I rather suspect that if you started researching from calcium oxalate and then branched into botany you might find that most plants contain the chemical including many vegetables we eat.

Anna said...

OMG! Just yesterday I looked up my aglaonema cultivar, Moonlight Bay, and found that it was created by one Dr. Richard Henny! And I have been devouring your posts a few at a time (so as not to totally overwhelm myself with new information, and actually learn something), so it's really neat to come across that little bit of fan-squee here.

Also, Jewish zombie slaves in Nazi Germany. Terrifyingly awesome.

Great article, good information. I've always had a difficult time learning by reading (and not hands-on), but your posts are so thoroughly accessible and funny that I've increased my plant-ID abilities tenfold in the week since I've been reading.

Anonymous said...

So although I was aware that dieffenbachia is poisonous, it didn't cross my mind when mine bit the dust & I broke it up with my bare hands & threw it into my backyard compost. "Boy, there's a lot of sap in this for a dead plant", I thought. And then "Hmm... I wonder why my hand feels so itchy? ...actually both hands..." And then the itch turned to burning & stabbing (damn crystals!).

It's surprising how little info there is for poor saps (ha!) like me who get this all over their hands. So here I sit, typing with mittens on so that the hydrocortosone I slathered on in a desperate attempt to stop the burning won't get all over my keyboard.

I guess some things you just learn the hard way!!

Anonymous said...

I have had the same fate as 'anonymous' so I am frantically searching for an effective remedy for very irritating skin hives on my fingers.
Initially I had just a burning sensation immediately after pruning and replanting cuttings of Dieffenbachia one week ago, so I applied an anti-itching cream just once and I thought that was the end of it. But it came back with a vengeance yesterday with hives and swelling of the fingers. Does anyone know what causes this delayed reaction? I am applying hydrocortisone and anti-histamine creams. How long will it take for my skin to get back to normal? What makes it better and what do I need to avoid?

FND said...

A great post. I love your style and humour. Thanks. I stumbled upon this post while researching dieffenbachia's toxicity. I've now added your blog to my regulars and look forward to hours of reading through the archives. Just one quibble:

"(What, they couldn't have the witness write shit down? Testimony doesn't count unless it's verbal?)"

Perhaps the witness was illiterate.

mr_subjunctive said...

FND:

Oh yeah. That does make sense. I forget how recent, and patchy, literacy is.

Julie said...

LMAO!!! This post is hillarious! Thank you for the good laugh.

Owen said...

Interesting read. One of my cats took to chewing on the leaves of my Dieffenbachia, and he has suffered no ill effects at all.

Lorax said...

Incidentally, Dieffenbachia are protecting themselves agains the following herbivores: Javelina, Peccary, Tapir, about 20 types of rodent, and Human beings. Birds don't seem to be a problem, and the bugs that eat them are adapted to eat just about anything.

This said, Here's something interesting for you... In Ecuador (one of the places that Dieffenbachia comes from), the tender young leaves of the plant are steamed and eaten. I've done this numerous times with various species, and they're extremely tasty. No ill effects, either. They taste kind of like Spinach (which, incidentally, has similar levels of Calcium oxalate crystals, but none of the nasty enzymes).

As for the Taro, it does indeed also contain oxalate crystals in the tuber, along with the lovely enzymes and raphides, but cooking neutralizes the effects.

And for those of you with sap on your hands, a quick wash in Vodka will remove the pain. (And if any of you are ever so unfortunate as to be bitten by bullet ants, the first thing you want to reach for is Dieffenbachia, since it will neutralize the venom and kill the deadening, screaming, oh my God I've Been Shot, pain that the bites cause.)

Anonymous said...

I found this blog while searching for info about my plant which my parents received as a wedding present in 1947. In the past it has reached 8 or 9 feet and then bloomed. Then I cut it down and hand out parts of the cane to friends and family to grow their own. This time I topped it, planted the top and it is blooming at 3 feet. But here's my comment: This plant has lived with children, cats and dogs for 65 years and none was ever poisoned. No dog ever got near it, no cat or child ever bit the leaves more once. If you get sap on your hands WASH IT OFF.

Anonymous said...

I just Stumbled across this and I've actually had a diffenbachia growing next to my bed for the last 17-ish years. I had no idea that it was poisonous. This was a very interesting read.

dog-towner said...

This is a very interesting discussion. Yesterday, I was watching an old episode of "Emergency!" (Jan.12,1974/"Messin' Around"), where John and Roy are called out to a house where a wife used Dieffenbachia sap to shut her hypochondriac up. You know, just make him mute. Well, the guys call it in to the hospital and Doc Kelly has no idea what Dieffenbachia is so he consults nurse Dixie. She tells them to blow it off. She says "no danger what-so-ever". She tells them that's why it is the "Mother In- Law Plant". To shut your mother in-law up. They laugh the whole thing off. John mentions that he wishes he had a couple of gallons of the sap to keep Chet quiet.
Can you imagine the law suits nowadays if some kid watched this and killed or just severely aggravated his mom with this stuff? Ah, the good old days. When you could imitate something you learned on TV, and not worry about the show and network being sued!

yankee doodleboo said...

Hey ! Iv just read this after doing a hell of a lot of research after accidentally ingesting my dieffenbachia today and ending up in hospital within 15 minutes. worst pain iv ever had hands down. 1 second after its in your mouth. Boom, like an invisible bomb went off that instantaneously stripped my mouth and throat of skin, completely raw, I was sobbing but couldnt make any noise just gutteral crap just pure agony that only intensified with every second! Uncontrollable continuous Drool stings to the floor, Tongue and airways swelled, id have panicked and probs died within 15 mins if my bf wasnt there as the house was empty! i was scared when the vains under my tongue too, up my whole underneath and were about to burst, my throat and pallette touching felt like knives cutting me open and replaced it with needles that went further down my throat each time I gulped water or swallowed. Worst Lasted for about 20 mins peaking at 10/15 mins , high pain after aaaa 6/7 id say for about 2 hours. it happened at 3 its half 12:am now and my throat feels like tonsilitis and my tongue now feels numb and tingly like stinging nettles but it settles very quick especially after antihistamines antiinflamatorys and milk !! Worst time of my life I was scared of the unknown and thinking how much longer till I cant bear to take another breath cos of my airways. I could hear my heart out my mouth so could my bf and my legs were like jelly and i went fainty. When i Bit into it and felt the juice come out omg, I hate all this playing it down i was scared shitless im 22 and was just dossing on my comp ripping the shoddy leaves off and forgot what it was in my hand and tbf thought it was inconspicuous and didnt even think. Steer clear, dont touch it its not worth it you could be dead within such a short time! Im making an infographic cos I want to now make ppl aware how dangerous this is especially people with kids or pets man cos we got that from homebase and another from ikea ! If a cat or kid got that sap on the fingers then eye or ingests or even chewed/licked any they could be gone! In a grizzly unforgiving way ! Living proof believe me! x

Erica W said...

Thanks for the darkly amusing, informative post. And thanks Lorax for the info about both herbivores and bullet-ant therapeutic use.

My hubby says he's tasted one once, apparently substantially less toxic than the one YankeeDoodleboo encountered (still not sure how you ended up eating it, but whoa that sounds hellish, and I'm glad you're feeling better).
He says the plant tastes nasty, not something that is going to attract repeat encounters. You'd expect anything with the ability to spit it out to do so.

Also, he wanted to add tortoises (hard, tough mouthparts) to the possible candidates for the Diffenbachia arms race.