Evil Genius (Kalanchoe daigremontiana)

Just a reminder for anybody who got excited when they saw a 0.0 rating: after I crunched the numbers for all the plants, I re-scaled everything so that the one with the hardest overall score got set at 10.0, and the one with the easiest overall score was set at 0.0. This means that you will still have to do something for your Kalanchoe daigremontiana if you want to keep it alive. (An artificial plant, remember, scores negative 0.3, not zero.)

Sorry to burst your bubble like this so soon, but it had to be done. If it helps, pretty much all you have to do is give it reasonably bright light (full sun is best, though it will live through a lot less than that) and not overwater.

So. This plant isn't, like, the bane of my existence or anything, but it's kind of obnoxious. We don't actually plant any of it deliberately, anywhere, and yet it's all over the place. How? Because it is much, much smarter than we are.

This is what it usually looks like:



Just a couple little plants happily mooching off of an unsuspecting cactus. Now, the first thing you might notice here is how damned close these plants are to the cactus's spines. That's because the plant is an evil genius, and has realized that it doesn't need to grow its own spines if it can just get the cactus to defend it. Which it does (the cactus does, I mean.). I do go through the cacti and succulents on a regular basis, picking out the weeds, but with stuff like this, if I don't want to go to the trouble of getting tweezers, I just leave it alone, 'cause it's not worth getting stabbed repeatedly. Sometimes I get stabbed repeatedly even with the tweezers and give up. And if I don't pull it out of the pot because it's too much trouble to do so, then the plant lives to grow another day: it wins.

But this is only the first layer of its diabolical plan, because it's also figured out another trick: it's incredibly brittle. When you go to pull it out of a pot, if a leaf or stem catches on the side of the pot, or on a cactus spine, or even the leaf of another Kalanchoe right next to it, leaves will break off and fall deeper into the pot, where you really can't get them without tweezers, and they will eventually sprout there and grow into new plants within a few months, that will have to be pulled out again.



The detached leaves don't even care that much whether they're in soil or not: the next picture shows some leaves that have sprouted in an empty spot in a plastic tray. Granted, they have a little bit of soil to work with here, because the tray is dirty, ¹ but it's still not what you'd call a nice little pot of soil or anything. Not even enough for a quarter-inch layer of soil. And they're growing anyway.



Another thing we can notice from this picture is that there seem to be two different kinds of plant here: one with sharply pointed leaves, and one with rounded leaves. (If you're having trouble seeing it, the two largest plants in the picture are the pointed kind, and the ones in the right top and right bottom corners are rounded.) I think that these are different morphs of the same plant (in which case it's also a master of disguise!), but I haven't bothered to let them grow out to check. I do know for sure that the rounded-leaf type will eventually grow up to develop spots and serrated edges, because I did grow one of those out, by itself, to see what it would do. So if anybody knows for sure that Kalanchoe daigremontiana is (or isn't) capable of changing its appearance like this, let me know. If not, I will be forced to grow out one of each and see what happens.

So, okay. It has minions (the cacti it gets to defend it), it hides so that you can never be sure whether you've really gotten it or not, it's a master of disguise. What else? Oh yeah: if you let it grow long enough, the leaves will eventually start growing baby plants on the edges. We don't actually encourage this to happen. When I started working there, there was one ponytail palm (Beaucarnea recurvata) that had two or three hitchhiking K. daigremontiana in the pot with it, that were big enough to produce plantlets, but I'm pretty sure the Kalanchoes in question have since been removed, or the plant itself sold, or something; I haven't seen it lately. So, I don't have original photos to share of this, but it's easy enough to find pictures on-line of this sort of thing (the species ID may not be exact, but the basic method looks the same for all the plants that do this):



What's going on here is actually very interesting, and is covered in excessively jargony detail here, in a post at sciencedaily.com. I'm not sure if we're actually talking about the same plant, because the picture they use for the article doesn't resemble any of the plantlets I see at work. (I think the picture is actually of Kalanchoe tubiflora, but I am not an expert in Kalanchoe taxonomy, and don't know anyone who is, so I'm just going with my best guesses here. My best guesses tell me somebody got the wrong picture.) The gist of the article is the same for any of the Kalanchoe species that reproduce this way, though: these plants have made a sort of deal with the devil. ² A gene which normally is only used in making seeds has been altered in such a way that it's useless for seed-making. Thanks to the changes, though, this gene can be expressed in leaves. So instead of forming embryonic plants in seeds, it forms embryonic plants in the leaves, skipping the whole pollination-and-seed stage entirely. ³

There are disadvantages: all of the plant's reproduction is now asexual, so there's no gene-shuffling going on at all from one generation to the next. Any pathogen that managed to crack the code and consume the plant would also be able to kill the plantlets, and grand-plantlets, and so on, and would be capable of wiping out all the plants in a given area within days. It's kind of like taking everything you own, putting it in separate rooms to protect it, and then putting the same lock on each of the rooms: yes, it's all separate, it's all protected from anything that can't open the door, but anybody who gets the right key can still come along and take it all. (Sexual species always have the hope that even if 99.999% of the population were wiped out by something, that remaining 0.001% could resist somehow, get together, and breed a new race of resistant organisms. ⁴ Asexual organisms like Kalanchoe daigremontiana can still change over time, because they still get hit by radioactivity and cosmic rays and ultraviolet light and so forth, so their DNA varies some, but change happens considerably more slowly, for various reasons which are beyond our scope. I can recommend books if you're really interested.⁵)

The plant might respond, call me stupid if you want, but I'm everywhere, and you aren't. You don't even have the power to make me go away, when you really, really want to. I'll be here long after you're gone. And then – the world will be mine! Then it would laugh maniacally, wait for thunder to crash in the background, and, I don't know, pet a cat or something.

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Photo credits:

Baby plants on edge of leaf: CrazyD at the Wikipedia entry for Kalanchoe daigremontiana.

All others: me.

¹ Yes, I am ashamed.
² See? Evil.
³ Though, weirdly enough, it still goes to the trouble of making flowers. I suppose even an evil genius can find time to relax with a hobby occasionally.
⁴ The name for this happening is "evolution," which you may have heard of.
⁵The Red Queen, by Matt Ridley, is a good one.