Pedilanthus tithymaloides is kind of a funny plant to research, since after you clear all the standard houseplant sites and plant sellers out of the way, what you are left with is a lot of scientific stuff that cannot be accessed without (expensive) subscriptions. So there's indication that a lot of work is being done on and with this plant . . . somewhere, but you, unless you have thousands of dollars to sink into subscriptions for publications like The Journal of Parasitology, have to make do with the abstracts, or sometimes even less than the abstracts.
So I know, for example, that Pedilanthus tithymaloides has been evaluated for use in controlling the organisms that cause malaria,1 schistosomiasis, and tuberculosis. It's been looked into as a possible renewable fuel source. Medical science is exploring it as the source of interesting anti-inflammatory drugs, or as a general antibacterial / antimicrobial. It also does something people find interesting when it's deprived of water for a while, and papers have been written about how the leaves won't change from green to pink without daily temperature fluctuations.2 And on and on in that vein.
In short, there seems to be general agreement that this plant must be good for something, or possibly many things, even, but at this point, in terms of confirmable information, we got bupkus. It'd be handy to come up with a use, since it's already invasive in India, and, you know, if it's going to grow itself without any help, it behooves us to find a way to use it all. We just haven't, you know, done that yet. (Or have we? Only the scientists know for sure. . . .)
So, like a lot of twenty-somethings, it doesn't yet know what it wants to do with its life, but no worries: it's still pretty. It'll get by.
The scientific interest mainly revolves around the sap, which is white and opaque and full of unusual compounds – granted, they're compounds produced so the plant can burn your flesh off,3 but we overlook that sort of behavior in a lot of other plants (for example, and another example, and a third example), so I see no reason to single out Pedilanthus tithymaloides4 for disapproval. As with these other plants, if you're doing some pruning or whatever, you'll want to use some common sense: take some basic precautions to keep the sap from touching your skin or eyes, and then if you get some sap on you anyway, wash it off.
Wikipedia, incidentally, makes the bold assertion "In Perú, it is called cimora misha and is sometimes added to psychedelic brews made from mescaline-containing Trichocereus cacti. Its pharmacology is unknown." So, wikiposedly,5 this is a psychoactive plant, but I suspect it's not a very good one if they 1) only use it "sometimes" and 2) the U.S. government still regards it as legal. But we can still, I suppose, add "psychoactive drug" to the list of things Pedilanthus tithymaloides maybe wants to be when it grows up, if it ever grows up.
Special Note to the stupid and/or impressionable: I do not recommend attempting to consume any part of this plant, by any means. I do not believe it is a psychoactive plant. I do believe it will probably hurt you. If you try this anyway, I accept no responsibility, and will point to this Special Note as evidence that I tried to talk you out of it.
My personal connections to this plant are mainly historical: I had one about ten years ago, when I was a twenty-something, that grew from a tiny little cutting into a mighty little shrub, and then eventually succumbed to . . . well, basically it succumbed to being ugly. I mean, ugly is why I got rid of it: it didn't have pests or rot or anything. The overarching reason is that I only had one north window in my apartment, and didn't always remember to water, and after watching the plant struggle with that for a while I was like, you know, I don't think this relationship is working out, so I chucked it. And then I moved, like, immediately, and wound up with a south window and no Pedilanthus, and realized I wanted one after all, and it took a good year and a half to track down another6 and I felt stupid.
So it's been nice to be reunited.
The main horticultural interest in the plant comes from its unusual habit: the stem changes direction each time it grows a leaf, forming a zig-zag pattern. This is the reason for the common name of "devil's backbone," though that seems a little presumptuous to me (where are the devil skeletons? The devil autopsies? The devil x-rays?). Another common name is "Japanese poinsettia," which makes about as much sense as calling French fries French or German chocolate cake German: the plant is actually a New World native.
Excitingly, part of its natural range is Southern Florida, which means that it probably isn't going to be a dangerous, ecosystem-wrecking invasive there like everything else seems to be. (Hawaii: you should still worry.)7 The leaves on variegated versions like mine also color up if grown in very bright light; when I bought it, the leaves were entirely hot pink with a green center, nothing whitish to be found anywhere. They then went cream/chartreuse for a time –
– and enpinkened8 again when I moved it to the south window.
They're grown outdoors in warm climates partly for the flowers, which occur in bunches at the end of a stem and are red and hummingbird-pollinated. Supposedly the flowers are bird-shaped, or possibly shoe-shaped, depending on who's doing the describing, but I haven't seen a close-up picture that's clear enough for me to see a resemblance to either one. (I also don't see that many bird-shoes or shoe-birds, which raises questions about the quality of the comparison in the first place.) This is, then, the story behind the other big common name, "redbird cactus," which makes about as much sense as calling the plant Bob, because the only part of that name that's true is "red," and that's only true when it blooms, which is not all the time.
There are a few cultivars (Oh! If anybody's reading this who has a cultivar other than the one pictured above, including the plain-green species, I would soooooooooo like to try to trade you something for some cuttings! Just FYI.). The species is plain green; I don't know if there's a particular name for the variety I have or not, though I've seen it referred to in a couple places as "P. tithymaloides variegatus,' so there may not be a variety name exactly. Glasshouseworks has the one I have, plus four others -- cupped leaves, smaller leaves, marbled stems, marbled leaves -- and Asiatica Nursery has two that they call 'Jurassic Park' and 'Jurassic Park 2.' (No word on whether they plan to make it a trilogy or not.) As always with Asiatica, I'm fascinated and intrigued right up until I see the price ($25 + shipping for a 3.5-inch pot!), and then I become significantly less interested.
Edited to add: I did eventually break down and bought 'Jurassic Park 2,' photos of which are located here, along with a review of Asiatica's service and so forth. 'Jurassic Park 2' does not appear to be a P. tithymaloides cultivar - the leaves are much too big and thick - but I'm not taking it out of the post because it's still a Pedilanthus (if anything is still a Pedilanthus, see footnote 4), and it's not likely to warrant a post of its own.
In any case. These are fairly easy, tolerant plants, though they do have a few non-negotiable needs.
Water: Plants can survive for a pretty long time without water; however, the only way this plant knows to communicate "Water now" is by dropping leaves, and it does that later than it ought to. This can be a good thing, if you're into the look this will produce: long bare zig-zag stems. I'm not opposed to the look myself, but for most people, you're going to want to hold on to the leaves, and in that case, you want to water only when the plant has just gone dry, not whenever you happen to notice that it's dry, because if you make it wait too long you will be looking at sticks.
Light: This is surprisingly negotiable, for a surprisingly long time, though if it's too dark for too long the plant will eventually start reaching for more light (if it's spring or summer) or stop growing entirely (if it's fall or winter), and then there'll be a point where every time you look at it, it'll be giving you big puppy-dog eyes and the idea will flit through your mind that maybe it should be euthanized or given to a good home or something. And then you will feel bad about yourself. So just give it good light from the outset. East or west window minimum, south preferred, and if it turns pink then you'll know you're doing something right. This is my own opinion, not that of the usual houseplant-advice places (which say bright indirect light indoors), but if you want it to turn pink I'm just about positive that you'll have to give it some sun, at least.
Humidity, Temperature, Grooming: All pretty much non-issues. Temperature, remember, is important because it's necessary for the pink color to show up (allege the scientists), but they seem to be capable of tolerating temperatures down to about freezing (and are hardy in zone 10, according to two different sources). Grooming is more or less limited to sweeping up dead leaves, and that only if you've been a very naughty waterer, though you'll get a bushier plant faster if you cut it back occasionally and plant the cuttings with the parent: they're reluctant to branch on their own.
Pests: I have never seen, or even heard of, Pedilanthus tithymaloides having a pest problem. That doesn't mean it doesn't happen, but it does mean that this is not a plant where you're forever going to be fighting bugs, like you would with spider mites and Hedera helix, or mealybugs and Cereus peruvianus (which, no, the situation with my Cereus is only barely improved: one plant seems to be better, the other still has them, and I just don't have enough time or Q-Tips to deal with this right now so I'm not sure what happens next.).
Feeding: I haven't seen anything specific about this plant needing any more or less fertilizer than your average houseplant. It does have a fairly marked dormancy in the fall and winter, when it doesn't do much, and I wouldn't bother feeding it then, but as long as it's in active growth, feed as normal, either every two or three months according to label directions, or half-strength twice as often.
Propagation: Propagation is easy, and basically amounts to just taking cuttings whenever the spirit moves you. Callus them by setting them aside for a day to dry (remember to avoid getting sap on anything you're going to want later), and then stick them in dirt. Or sand. Or damp perlite. Or water. Pretty much whatever's at hand. Rooting will be faster with some of these than with others (I'd favor regular potting soil, possibly with some perlite or vermiculite mixed in.), and it's better to do it in spring or summer than fall or winter, but it will eventually happen.
This is probably never going to be a major part of the tropical foliage industry: it's a little too dangerous, a little too needy, a little too weird (though I'm realizing, as I talk to more and more customers, that for any given plant, there's somebody out there who hates it, and somebody else who thinks it's the Coolest Thing Evah). But you will be seeing it somewhere, in large quantity, just as soon as it figures out what it wants to do with its life and settles into a career of some kind. Whether it's going to be a doctor, exterminator, drug-pusher, or some kind of alternative-fuel hippie, only time will tell.
Photo credits: all photos are my own.
1 (Though it doesn't seem to be very good at it)
2 Which changes in color also seem to be linked to the activity of an enzyme called peroxidase. Peroxidases are proteins which break down hydrogen peroxide (H2O2, the same stuff one disinfects wounds with, or bleaches hair with) into water and oxygen. Different species have differing peroxidases, but the need for something to split up hydrogen peroxide is a pretty universal need, and so peroxidases are found in plants, animals (including humans), fungi, and bacteria.
3 (Exaggeration. It can cause irritation, but it's not even in the ballpark of some of the nastier Euphorbias.)
4 Possibly now Euphorbia tithymaloides. It's not clear to me whether this is an official name change, but the same forces at work in renaming Synadenium grantii to Euphorbia pseudograntii would seem to be operating here, so I'm guessing if one changes, they both change.
5 I originally saw this "wiki-supposedly," but I don't remember where, and searching the net didn't turn it up. I think wikiposedly sounds better anyway. It would obviously be defined as,
wikiposedly \wi·kē·'pō·zəd·lē\ adv. 1 a Alleged to be true according to Wikipedia, though in fact untrue, 1 b unverifiable, or 1 c improbable.
6 In Ames, Iowa, at a weird organic-greenhouse-slash-antique-store previously mentioned in Clivia miniata. This is also where the Sansevieria trifasciata 'Bantel's Sensation' pictured at the bottom of this page came from. I would have gotten more plants, but 1) on that particular day, there was a big storm blowing into Iowa, and the husband and I were sort of racing the storm home, 2) I only had just so much money to spend on the trip and I'd used a lot of it already, and 3) there were some serious pest problems on some of the plants, including the single creepiest case of aphids I think I've ever seen. I mean, I'm all for organic growing and stuff, but given the choice between a raging insect problem and some pesticide, I'm going to go with the pesticide every. Single. Time. That said, props to the guy for having a lot of stuff there that I've either only seen for sale at his place, or I've only rarely seen somewhere else, and it was all more or less alive, so perhaps I just caught him on a bad week. Some googling turned up a place called Ames Greenhouse and Antiques, at 3011 S Duff Ave, Ames IA, 50010, which can be reached by phone at (515) 232-1332, and judging from the look of the map, I'm almost positive that this is the place in question. And if you check it out, tell them Mr. Subjunctive sent you. (Not that they know who I am, but it amuses me to think that someone might say this.)
7 (Explanation for newcomers to the blog: there are enough houseplants that have become invasives in Florida and Hawaii that it's somewhat of a running joke here. It's not actually funny: some of these really could do, or have already done, actual damage to wildlife. See also Asparagus spp., Sansevieria trifasciata, Syngonium podophyllum, Murraya paniculata, Tradescantia pallida, Epipremnum aureum, and Ardisia elliptica.)
8 Well, it ought to be a word. Though I might prefer empinkened instead. Haven't decided.