NOTE: Initially, I identified the plant in this post as Euphorbia grandicornis. Then I got a real Euphorbia grandicornis and wasn't sure what this plant was anymore. I've settled on a guess of E. pseudocactus, based largely on the pictures of it at davesgarden.com, but: 1) this could change again if I decide I'm wrong about E. pseudocactus too, and 2) the HTML address for the post still says E. grandicornis. Apologies for any confusion this may have caused. If it helps, virtually everything said herein about E. pseudocactus could also be said, just as accurately, about E. grandicornis.
I mentioned previously, in Euphorbia trigona
, that in my quest to buy Euphorbia ammak
, I bought two other plants by mistake first. This, obviously, is the other one.
My own plant. (Once again, the file name for the picture has the wrong ID. I'm really very sorry.)
This plant is not widely sold where I live (in fact, I've seen exactly two of them, and one of those was nearly dead), but it appears to be a lot easier to find elsewhere (in the desert southwest in particular, and California especially), judging by the sites that pop up in a Google search. I kind of get the impression that it's even harder to come by in its native habitat of southeast Africa (primarily South Africa and Swaziland
), though this is tough to confirm.
A few websites I ran into, more than you'd think would be statistically likely, offer warnings along the lines of this plant isn't for beginners
. I suppose there's an argument to be made, there, but I haven't seen any indication that this plant is any more difficult than other succulents from the same family. It needs a lot of sun, reasonable indoor temperatures (I wouldn't go below 50ºF / 10ºC), and water only when the soil is almost completely dry. A quick-draining, very lean soil is obviously helpful in preventing overwatering (and the heartbreak of rot that comes with overwatering). Too much sun, or too sudden of an increase in sun, will cause bleaching and spotting and all-around stress (e.g. if the plant's been inside a shop waiting to be sold for six months, and then you buy it and throw it out into the middle of your yard all summer).
Propagation is said to be pretty easy (I haven't tried it myself), and is essentially the same as what I described for E. trigona
: cut off a piece, let it dry in a bright place out of the sun for a few days to a few months (2 weeks was the specific example given here
, but I don't think the particular duration of time is as important as the fact that there is
some callusing time. Planting immediately after cutting invites rot; waiting too long to plant could leave you with a curved plant (even if it's laying down on a bench somewhere, the cutting will still have a phototropic response: over time, this will result in a tendency for the plant to bow upward unless it's rotated). The site I linked to also used rooting hormone: I'm agnostic about the usefulness of rooting hormone with Euphorbia
s (or, in fact, pretty much anything else).
This species, and the many similar species of upright Euphorbia
s with many spines, are often used inaccurately in TV shows and movies to announce "cactus" or "desert" or (very occasionally, in your more symbolic shows) "mean person" to viewers. I'm fuzzy on the reasons why,1
but it happens often enough to be worth noting.
This is one of the more cactusy-looking Euphorbia
s, hence the botanical name (pseudo
meaning "false," plus cactus
meaning "cactus"), though a lot of the African succulent Euphorbia
s look enough like cacti to be confused with them. So, now might be a good place to go into detail about how the Cactaceae are not Euphorbia
s, and what's the difference, and why it's not just something botanists and pedants came up with to hassle people about. In the end, hopefully, you'll have laughed, you'll have cried, and you'll have learned a little bit about yourself, and those of you who were really
paying attention might even learn a little something about the true meaning of Christmas, though I make no promises.
Let's start with why it's important. The Cactaceae / Euphorbia
resemblance is an excellent example of convergent evolution
, the term for when two species or groups which aren't terribly related to each other wind up in similar environments, and then solve the problems of those environments in ways that look and function more or less alike.
In the case of Euphorbia pseudocactus
, we can see certain obvious adaptations to arid environments: a water-storing trunk, complete lack of leaves to minimize moisture loss via transpiration (some Euphorbia
species, like E. trigona
, continue to produce leaves, but these are small, pathetic, and apparently pretty disposable), thorns and irritating sap to discourage predation,2
a waxy coating to minimize water loss through the stem, a mostly-vertical columnar shape to cut down on sun exposure during the hottest part of the day, and so on. And with a typical cactus, say Cereus peruvianus
? Well, we have a water-storing trunk, leaves reduced down to sharp spines to discourage predation, a waxy coating, a mostly-vertical shape, and so on.
What does this prove? Well, not much of anything on its own, but it's indirect supporting evidence for the theory of evolution:3
although there are plenty of indications that the ancestral cactus and the ancestral Euphorbia
were very different from one another (e.g. their flowers are not particularly similar, Euphorbia
s have irritating white sap and cacti don't, cactus spines are modified leaves, and emerge from super-shortened branches called areoles, whereas Euphorbia
spines are part of the stem, and some of them still produce leaves), there turn out to be only just so many good ways to cope with the conditions of desert-like environments.4
The most impressive photo I could find to show this is here
, down at the bottom of the page: not only is there a cactus and a Euphorbia
that look a lot alike (I think the Euphorbia
might be E. lactea
), but they also rounded up a third plant, from the Asclepiadaceae, or milkweed / Hoya
family, that looks like the other two, which sort of strengthens the point further.
A very quick and rough guide to telling Euphorbia
apart from cacti:
If the spines are paired and at an angle of about 100º to one another, as in E. grandicornis, it's a Euphorbia. Cacti almost always have more than two spines (usually more like eight) at an areole, pointed in every direction.
If the plant bleeds a white, latexy substance when poked: it's a Euphorbia. Cacti usually (I hesitate to say always, though I'm unable to think of any exceptions) have clear sap.
If the plant has conspicuous true flowers (as opposed to nondescript flowers surrounded by flashy bracts, as with poinsettias), it's a cactus. Euphorbia flowers tend to be small, yellowish green, and in clusters.
It's not generally all that relevant, practically speaking, whether you're looking at a thorny cactus or a thorny Euphorbia
: they take more or less the same care. But sometimes one wants to know anyway.
The more-cactusy-than-cactus phenomenon that leads Euphorbia
s to sometimes find themselves in botanically and historically inaccurate TV settings (there was an actual example of this not that long ago, but of course I can't remember the show in question because I didn't write it down immediately: bloggers take note) is a bit like the more-cowboy-than-cowboys phenomenon: Japanese tourists who go to rodeos in cowboy boots and ten-gallon hat, city slickers who wear cowboy shirts and big belt buckles to clubs but couldn't ride a horse any better than a barstool, yuppies who take dude-ranch vacations, etc. I saw this from time to time when I lived in Texas, though not being a cowboy myself, I couldn't say how the actual cowboys took that sort of thing. Probably either stoically, or as the excuse for drunken bar brawls, since those are pretty much the only emotions permitted to cowboys.
Of course none of this is the plant's fault. It's being as authentic as it can.
Photo credits: in text.