Paranoiac (Euphorbia trigona)

This is one of a series of plants I bought during a quest to get one particular plant. The plant I wanted was Euphorbia ammak; I wound up buying E. trigona and E. pseudocactus first, and then eventually got two enormous cuttings of the one I really wanted from someone on Garden Web.¹

The nice surprise is that all three have turned out to be great additions to the group, though in different ways. Euphorbia trigona had one quirk that I haven't seen anyone else describe before, though, which was: it waited to see if I could be trusted before it started to grow. Or at least that's how it looked to me.


The original plant had both of these stems potted together; I divided them when I bought it and gave them each separate pots. And then for the next year, they just sat there. The taller of the two got a little taller (less than an inch, but enough to be detectable), and that was all. Then, suddenly, around September of this year, they started to branch, and they both got taller as well, and now I guess we're off to the races. Apparently they finally decided that I wasn't going to hurt them, or something like that.

There was one other odd moment with these. At some point last winter, they both started to get brown and tan patches in the center of the main stems, though only on one side:


I never figured out what started this, and I never figured out what to do to stop it. The plants just kind of quit on their own. My best guess is sunburn, which fits in some respects (the affected sides were the ones facing the window, and the brown started with a reddish color, like some plants get when they're sunburning) and not in others (this all happened in winter, the season without a lot of sun). I suppose if it starts up again this year, we'll have a theory.

This is not a difficult plant to keep, though there are some things to bear in mind if you're going to get one. First, they are a Euphorbia species,² and as such, there's some dangerous sap involved. How dangerous? Hard to say. I have seen one account recently (in the comments) by a guy who says he got Euphorbia trigona sap in his eyes and was blind for two days as a result. Also there was apparently excruciating pain. There are also a number of accounts of people getting blisters when Euphorbia sap (not necessarily E. trigona) dripped on them, and occasional, impossible-to-verify reports of people having reactions just to breathing the air in the vicinity of a cut plant.³ I suspect that there's some hysteria and suggestibility involved here, and also that people may be getting different species mixed up, but even so, Euphorbias are not wholly benign and should be treated with a certain amount of respect and common sense. Eye protection, in particular, is probably a good idea: they squirt latex when cut often enough, and the consequences if you get some in your eye are severe enough, that taking the ten extra seconds to put on a pair of goggles (or wraparound sunglasses, even) is going to be worth it, on average, if you're going to prune one. The only other thing I do with Euphorbias is make sure to have some paper towels handy, if I'm going to be making a cut. I try to cover the side of the cut closest to me with the paper towel, so that if it should squirt latex in my direction, I won't get sap shot into my face. (It's also handy to have paper towels because sometimes they drip for a while after being cut.)

For less traumatic plant maintenance, like picking off dead leaves, or repotting, I personally don't go to any extra trouble to protect myself, but then, I don't react to Euphorbias particularly. Occasionally I get a little itchy.⁴ Even so, I wash pretty carefully after dealing with these plants for any length of time; my skin may be fine, but if I forget about the Euphorbia sap and rub my eyes, I'm screwed. So I wash anyway. Rubbing alcohol is said to be useful for dried sap, by the way, if you find some you'd forgotten about.

So, if you have pets or small children, this is probably not the plant for you: even setting the sap aside, there are still thorns, and the plant does tend to be top-heavy over time. This is not a good plant for high-traffic areas, for people with small children that might stick pieces of it in their mouths, for people with large pets that could knock it over, or for placing on tall stands.

Now that I've completely scared you away from ever wanting one of these, let's talk about how you would care for them if you were to get one, which you won't.

Light and watering are the primary things to watch here; there are Euphorbia pests, but they tend not to be a huge deal. (At one time, I thought that mine had had whitefly, but I'm doubting this in retrospect; mealybugs or scale are probably more likely and/or more damaging. Euphorbias in general are pretty hardy folk.) Most propagation is by cuttings – just lop off a piece, let it dry for a few days to a few weeks, and then plant it. Start watering when you see new growth. My impression is that cuttings rarely fail, but are slow enough that they can try one's patience: I have yet to see the Euphorbia ammak cuttings I mentioned earlier do anything, despite having had them for six months (on the other hand, a E. lactea cutting I took at work has rooted already, so there's some variation from species to species and situation to situation). And of course you do have to feed once in a while, but that's not really a big deal. Light and water are big.

Light: These don't necessarily have to have full sun, but they do need very bright light or they will become thin and weak. Drastically increasing light intensity can lead to problems: if you're going to bring an indoor plant outside, do so gradually, in steadily-increasing intensity and duration. If you just chuck it out into the middle of the front yard, it'll burn and burn and burn.

Water: Euphorbia trigona actually tends to be a pretty problem-free plant, when left to its own devices. As with any succulent, rot is a concern, but it's not inevitable. Drench the plant with water when the soil is almost completely dry, then allow it to dry out almost completely before watering it again. If a plant has begun to succumb to rot, cutting the rot away with a clean knife is more likely to work than trying to poison it away with a fungicide. On a large plant, one may be able to cut away the affected tissue with a clean knife, though this depends on where the problem is located and how widespread it has become. If the plant's base is completely gone, you can still take cuttings and root them, as described above.

There is at least one cultivar: I'm unclear on the name, but I've seen it labeled 'Red,' 'Royal Red,' or 'Rubra.' It is, as you would expect, red:


I haven't seen anything to suggest that it is any more or less difficult than the normal green variety. (UPDATE: I did eventually get one. They're not any more trouble than the green variety, though the red color will fade if the plant's not getting enough light.)

E. trigona is often confused with another commonly-sold Euphorbia, E. lactea. The confusion is understandable; the stems are remarkably similar. Once a plant has branched, though, it's easy enough to tell the difference: E. trigona branches, once sprouted, remain close to the original stem, and grow parallel to it. E. trigona also grows small leaves on new growth: the leaves form between the thorns. In E. lactea, on the other hand, branches grow out away from the main stem at an angle, and may or may not ever wind up vertical. The result is that E. lactea has a more open, treelike form, and is thus unpleasant to bump into from any angle, and takes up more space, pound for pound, so you're more likely to bump into it; E. trigona is harder to hurt yourself with, unless you ignore warning signs about a shifting center of gravity.

Euphorbia lactea
Finally: I would hope that nothing written here deters anybody from buying one of these plants, if that's what they want to buy. I figure it's important to get people's attention, so they have a safe amount of respect for the plant, but it's not like the plant is going to come after you in the middle of the night with a sawed-off shotgun. It's all common sense, really, I swear.

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Photo credit: all mine.

¹ Enormous to the point where I was a little concerned that people might think I was getting severed human arms in the mail. Apparently, either 1) nobody thought that, or 2) people send one another severed human arms all the time.
² Also: Euphorbias are not cacti. Very few things will rile up a pedantic cactus and succulent collector quicker than calling a Euphorbia a cactus. A lot of them have spines like cacti, they come in the same shapes as cacti, they serve the same general function in their ecosystems as cacti, you can root cuttings of them like cacti, and they are virtually interchangeable with cacti in every other respect, but they are not. Cacti. What's the difference? Oy. How about we go back to the main text and let me tackle this some other time? Or, if you just can't wait to find out, you could read this: it's not inaccurate, though I think it fails to make some distinctions that need to be made. It was the best answer I could locate, though.
³ Particularly the species E. cooperi, which has a fearsome reputation, and gets mentioned often enough that one assumes people aren't just making up stories about it. E. tirucalli ("pencil cactus," or "Firesticks") also has a lot of stories out there, and I'm more careful with that one, too. E. trigona, our subject here, has a lot of warnings, but few actual stories about it causing damage or irritation, and it's pretty widely sold, so it's clearly not a total ninja like E. cooperi that can kill you seven different ways in the blink of an eye. So don't panic: just don't forget what you're working on, and that you need to be mindful of where the sap is going.
⁴ Though, for itchiness, nothing at work has been worse than picking dead and yellowing leaves out of Ficus benjamina trees, which I can literally only do for a couple minutes before I have to run screaming to the sink. I suspect this is at least partially psychological, since I'm beginning to itch right now as I type this, but even so: there's something about Ficus benjamina that makes me itchy even when I'm thinking about other things entirely. My current theory blames pesticide residue, since the same thing happens sometimes when I weed under the tables in the greenhouse.