Folding Leaves at Night, Cool!

bearstate(9A)June 28, 2007

I've got several Cassia Alata or also called Senna Alata, seedlings going and they do a marvelous thing at night ... their leaves fold up!

It kind of reminds me of what Mimosa Pudica ( The Shy Plant ) does, but Cassia Alata's leaves don't fold when you touch them.

You can actually watch them fold however if you are patient at dusk.

This is a very interesting and easy to germinate plant that grows shrub height and produces many candelabra like yellow flowers ( also know colloquially as the candelabra plant ).

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Very Cool!!

    Bookmark   June 28, 2007 at 6:08PM
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I wonder what the natural selective pressure was that produced a plant that does this sort of thing?

Does it somehow keep something from eating it? I wouldn't think so. Does it maybe let evening rain water reach the soil instead of being shed away by the open leaves? I wouldn't think so.

Why would a plant specialize in this way?

    Bookmark   June 28, 2007 at 7:04PM
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Plants that exhibit day/night folding-leaf cycling are described as being photonastic. They can be "trained" to respond to different photoperiods as follows:

* Move the plant to a darkened room and set up a light source that can be regulated to turn on and off with a timer
* Start with a 12 hour on/12 hour off schedule at 1st
* Slowly, over several weeks, reset the on/off light cycle to progressivly shorter photoperiods
* When your plant is able to open and close its leaves every second or two (be patient,this may take a long time), get a strobe light, aim it at the plant and, with practice, you can fly the plant around the room.

Make sure that you don't turn off the strobe when the plant is flying might fall on your head. That happened to me and I'm still having these terrible headaches....

    Bookmark   June 30, 2007 at 10:51AM
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Now that would be very very cool, especially since I like to fly. I figure that with a super-sized pot and some way to cause to plant to fold and unfold those leaves to provide directional control, attitude, yaw and roll, I could be the hit of the air show. But the FAA probably wouldn't go for an experimental of that type. While the strobe might serve a requirement and directional running lights could be added, there are a whole pile of other specs that the FAA would demand. Sadly, I'll just have to plant my Cassia next year and after they overwinter, watch them grow into shrub size proportions and flower brilliantly.

But now levitation, that's the ticket for me. Mind control. It would be such that I levitate objects at first, then ... why then, myself! But to protect myself from bird hits ( understanding that I am not a caped superman ), I would find a way to get in my compact automobile and levitate it. I'd have perfect directional control and would start out by driving normally down the freeway and then ... just a couple inches off the ground. Those people who would notice, would be startled and awed. They'd get on their cell phones and flood 911 ... "There's a car flying down the I-5!" The highway patrol would respond and as they came up on my six, their lights flashing and the officer on his mike demanding "All right! Get that thing back on the ground and pull over!", I would climb skyward, bank off to the east and zip at lazer toward, now let me see ... yes ... Edwards Dry Lake. The idea here would be to make them believe it was a government thing and I would then cruise back to some back road, touch wheels and return home, parking my flying car in the garage so that the lookielous and investigators who likely saw my plate number won't be able to use a can opener on it ... a fat lot of good it would do them!

That's imagination.

Thanks for the thought. My imagination was stirred.

    Bookmark   June 30, 2007 at 11:27AM
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Just as a point of interest , it seems to me , though I'm sure there are exceptions, that that trait may be a common one passed through evolution into many species of just one family, and there are a number of families as well , where that's a common trait. Now, not wanting to mess up too badly when it comes to figuring out families, it seems my Powder Puff "Calinandra" does that as does the Delonix, and many from the group of of the Leguminosae, or Fabaceae, but of course also those related to prayer plants. I'm not sure if there wasn't some speculation that it's sort of a defense against night munching insects, which may find the folded leaves harder to munch on?

    Bookmark   July 1, 2007 at 8:01AM
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While it is always possible that there are some insects that may be dissuaded from munching on folded leaves, it seems unlikely. Insects can still get at the edges of the leaves and the little buggers typically rasp right through surfaces. I don't think protection against insects is the deal here.

Of course, there are bigger things that eat leaves, but they would munch during the day. And hey, what's to stop insects from munching during daylight hours, strong sunlight?

When these plants are fully grown, I have to assume the same behavior persists. But the selective forces that evolved such plants may have a lot to do with their sappling survival - eh?

Photonasty is apparently not the thing here. Many plants display photonastic movement, typically associated with leaves moving to track the sun's movement for more direct exposure. Flowers especially, are cited for their photonastic movements. Cassia Alata does exhibit photonastic movement and the young plants look like they are deploying their leaves like solar arrays to not only track the sun, but expose the most leaf surface at the same time.

The folding behavior at night I've found from digging, to be called 'nychinastic sleep movement'. Unfortunately, none of the references I've found shed any light on the reasons for nychinasty. Certainly, photonasty has a direct reason for the selectivity of plants with this behavior. But nychinasty?

There are other nastic movements as well, chemonasty, hydronasty, thermonasty, geo or gravinasty, and thigmo or haptonasty. Mimosa Pudica's response to touch is thigmonastic movement. I suppose a venus fly trap also displays thigmo or haptonastic movement and the selectivity there, is obvious. Mimosa Pudica may disturb and ward off munchers by its thigmonastic leaf folding, but nychinastic sleep is static, once the leaves fold.

So nychinastic folding of leaves is a mystery and no suitable explanation seems to have been put forward, at least not one on the web, where you'd think you could find anything worth the gossip over or the intelectual pondering of.

My best guess is that nychinastic sleep serves absolutely NO protective value in plants. It simply occurs because the plant mechanisms responsible for photonasty during the day, shut down at night, causing the folding. The perfectness of how the leaves fold together in groups may have been selective over time, simply because if they folded haphazardly, they would damage themselves. The folding is so perfect, that manufacturers of folding tables have copied the basic structural aspect in their table designs. So I scratch my head and wonder ... but who am I and what the heck to I know? It seems more is known about moon rocks and the geology of Mars than nychinastic sleep in plants ... The eggheads marvel only about what chemicals are involved in the movement and not at all, the selective causality.

Folks, we have discovered an intellectual black hole that only imagination can escape from. Let's return to those strobe lights causing Cassia to fly.

    Bookmark   July 1, 2007 at 12:49PM
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Ok, let me take a flying leap at a rolling doughnut guess at this.

I have observed that 1) the biggest leaves on Cassia Alata are the topmost and that 2) coincidentally, the topmost leaves ( not entirely, but almost all ) fold up first. And 3) the plant seems to be adapted to make maximum exposure to the sun, both by having those enormous topmost leaves and by being able to photonastically track the sun as it passes overhead.

It seems therefore, that nychinastic sleep movement folding of the leaves must be an adaptive trait to further maximum chloroplast exposure to the sun. The small leaves under the big ones are completely blocked most of the day, partly explaining their smallnest or dwarfism. It would seem suitable that they be afforded some light during the day, either during the failing light of dawn or dusk. But they too, eventually fold. All the leaves have the mechanism. It's just that the hidden leaves fold last and though I haven't observed yet, probably open first.

If someone else has a nychinistic sleep movement plant that exhibits leaf folding, see if like a good scientist, you can confirm my finding.

Note, I have a plant here that does nychinistic sleep movement of the flower ... California Poppies. The flowers of California Poppies close at night.

    Bookmark   July 2, 2007 at 4:29PM
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I had to re-read these posts quite a few times to realize you guys are joking about flying plants! just dont tell anyone.....:)

    Bookmark   July 3, 2007 at 12:11AM
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garyfla_gw(10 Florida)

Have cassia roxburghii and it doesn't seem to fold at all. Have noticed that Calathes tend to fold upwards while marantas go down.But not always. Marantas will fold during the day if the light is too bright. Have a rabbit tracks maranta growing at the edge of an aquarium and it actually folds it's leaves into the water.. Surprises me as it doesn't seem to bother it at all. Keeps right on growing lol. Had a Calliandra ,powder puff plant for over 10 years
before I noticed that it folded at The leaves fold together into a clump. looks much like severe wilt .Almost drowned it before figuring out that it's natural lol gary

    Bookmark   July 3, 2007 at 5:03AM
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Sounds like you have a lot of nychinasties. LOL. But they can't be that bad as it doesn't sound like they've flown away on you yet. But then you probably don't have a strobe light ...

So, do the topmost leaves fold first at night? Do they open first in the morning?

    Bookmark   July 3, 2007 at 3:11PM
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The following photo is proof that folding leaf or nychinastic behavior in Cassia Alata does NOT protect it from being ravaged by insects ...

The big bite marks on the leaves of this Cassia Alata are due to a small fly. It looks a lot like a normal house fly, except that its abdomen is not bulbous, but is narrow and pointed and has a metallic blue color. I don't know what kind of fly it is, but the fly itself, not larvae, is eating away at this Cassia.

I have sprayed with Ortho insect spray twice now, but the flies come back after watering rinses away the insecticide. They seem very persistant and attack just one of the many Cassias that I have, regardless of whether the leaves are folded or not.

Another interesting aspect of Nychinastic behavior in Cassia is that the leaves fold not only at night, but if the plant is put in direct sunlight.

Very interesting indeed.

    Bookmark   July 28, 2007 at 8:21PM
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wanda(Z9 CA)

Those are typical "bite marks" of the Leaf cutter bee, a relatively harmless pest

    Bookmark   July 31, 2007 at 6:18PM
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Does the leaf cutter bee look like a fly with a pointy blue butt?

    Bookmark   July 31, 2007 at 9:37PM
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