Neurotic (Maranta leuconeura erythroneura)

After my experiences with Calathea ornata, I swore off the whole Marantaceae family.¹ Not that they aren't beautiful, but I couldn't face the heartbreak again. And that worked for a while, but I have limits, and anyway, I read somebody saying that Maranta was easier, in general, than Calathea, in general, so there was that tiny sliver of hope. And then I saw a small one for sale for like $3, and bought it "just as a test run." Because I am weak.



And, not to ruin the suspense or anything, but I didn't wind up having any serious problems with the test plant, so I bought another and potted them together, and everything seems to be fine. So hooray for me.

The main differences between the two are temperature, humidity, and ease of propagation, as far as I can tell, with Maranta being easier on all counts.² The differences are not huge: you still don't want to cook or freeze your plant, and it's not impossible to propagate Calatheas either, but the humidity requirement does seem to be significantly more relaxed for Maranta. Both genera are a little difficult when it comes to watering: you never want them to actually dry out, but if you water too much, they're likely to have small fits. (Mine drops a leaf or two just about every time I water, though it grows them back faster than that, so we're good.)

What the plant is known for, though, is its habit of holding its leaves vertically at night and horizontally during the day, which goes by the charming and memorable technical name "photonasty."³ The other members of the Marantaceae do this too, to some degree, but it's most dramatic in Maranta. According to this site, which is actually about Ctenanthe (I think it's safe to generalize on this point, as closely related as the two genera are), the movement is driven by two light-sensitive pigments in the plant: one is sensitive to red light, and raises the leaves; the other is sensitive to blue light, and lowers them. (Presumably, if you shine purple light on the plant, it begins to flap its leaves and flies away.)⁴ The actual raising and lowering is accomplished by pumping water into, or out of, specialized structures at the base of the petioles.⁵

I looked and looked, but couldn't find any watchable time-lapse movies⁶ that covered a full 24-hour period; I did track down this one and this one, both of which are short, but long enough to give you the general idea.

As far as I'm aware, there's no definitive explanation yet for why they move, but it's not hard to see how it might be helpful: vertical leaves at night will catch dew and funnel it down toward the plant; horizontal leaves during the day make the best use of the light-collection surface. I prefer to think of it as a Maranta-specific form of neurosis, like the plant's practice of rolling up new leaves super-super tightly before unfurling them.

To go along with the special-effectiness of the time-lapse thing, Plants Are the Strangest People is in 3-D! for the very first time with this entry. The below photo works more or less like one of those Magic Eye pictures, in that you have to cross your eyes a bit in order to get it to work. If you can cross them such that features in one picture overlap the same features in the other one, you should be able to fool your brain into seeing it as a single three-dimensional image. It's not the most exciting three-dimensional image. But if this works for enough people, it could open the door to future pictures which are bigger, more detailed, more relevant, or whatever. So let me know if it works for you.



There is also a variety known as "Maranta leuconeura leuconeura," which is frequently referred to but never pictured. Besides that, the verbal descriptions of it (in the few places one can find descriptions) are pretty close to being word-for-word copies of one another, which makes me wonder. At work, we have the plant pictured below, which differs from the plant above only in that the ribs on the leaves are green instead of red: it's possible that this is the plant in question. It is also possible that it is not. The tag that comes with the plant only gives the ID "Maranta leuconeura 'Marisela'," which the sharp-eyed reader will have noticed is something different altogether. I like this plant, though, which we have at work. I haven't bought it yet, because among other things, I'm still waiting to see if the erythro version is going to make it through the winter. If it does, though, I'm all over this 'Marisela' thing.


UPDATE: (30 Jan 2010) These do need to be watched for pests, unfortunately. I've personally lost plants both to spider mites and to mealybugs, which happened soon enough after purchase in all cases that I've been convinced not to bother with this genus anymore. Were it not for Stromanthe, I wouldn't bother with the whole Marantaceae family, but so far, Stromanthe and I get along strangely well, so they're the exception.

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Photo credits: all me.

¹ (Which includes the genera Maranta, Calathea, Stromanthe, and Ctenanthe, though only the first three are sold commonly enough in my area to matter for swearing-off purposes.)
² (It does, however, require a bit more in the way of grooming, since it grows more quickly, drops more leaves, and flowers more – this wouldn't be a big deal except that unlike many plants, Maranta leaves often don't detach cleanly when they die, and almost always have to be cut off. Calathea leaves don't either, really, but they're slower to drop leaves, grow leaves, and everything else, unlike the fast-living, pretty-corpse-leaving Marantas, so there's less to clean up.)
³ "Photonasty" technically refers to any movement of a plant part which depends on light but does not change according to the direction the light is coming from. In other words, when your Syngonium grows toward the window, that's phototropism, but when your Hibiscus opens its flowers in the morning and closes them at night, that's photonasty. I think.
⁴ (Kidding. Obviously. But wouldn't it be cool?)
⁵ Petiole: the "stem" that connects the leaf to the actual stem, or the rhizome, in those plants that grow from rhizomes.
⁶ (I found a couple unwatchable ones. One refused to load within a reasonable amount of time, and the other crashed my browser.)